System R 30

Modular Test Van

USER GUIDE
Issue: D (10/2022) - EN
Article number: 128311867

1
2
Consultation with Megger

Consultation with Megger

The present system manual has been designed as an operating guide and for reference.
It is meant to answer your questions and solve your problems in as fast and easy a way
as possible. Please start with referring to this manual should any trouble occur.

In doing so, make use of the table of contents and read the relevant paragraph with great
attention. Furthermore, check all terminals and connections of the instruments involved.

Should any question remain unanswered or should you need the help of an authorized
service station, please contact:

Megger Limited Megger Germany GmbH (Baunach)

Archcliffe Road Dr.-Herbert-Iann-Str. 6
Kent CT17 9EN D - 96148 Baunach
T: +44 1304 502100 T: +49 9544 68 – 0
F: +44 1304 207342 F: +49 9544 22 73
E: uksales@megger.com E: team.dach@megger.com

Megger Germany GmbH (Radeburg) Megger USA

Röderaue 41 Valley Forge Corporate Centre
D - 01471 Radeburg / Dresden 2621 Van Buren Avenue
Norristown, PA 19403 USA
T: +49 35208 84 – 0 T: +1 610 676 8500
F: +49 35208 84 249 F: +1 610 676 8610
E: team.dach@megger.com

 Megger

All rights reserved. No part of this handbook may be copied by photographic or other means unless Megger
have before-hand declared their consent in writing. The information in this document is subject to change without
notice and should not be construed as a commitment by Megger. Megger cannot be made liable for technical or
printing errors or shortcomings of this handbook. Megger also disclaims all responsibility for damage resulting
directly or indirectly from the delivery, supply, or use of this matter.

3
 Terms of Warranty

Terms of Warranty

Megger accept responsibility for a claim under warranty brought forward by a customer
for a product sold by Megger under the terms stated below.

Megger warrant that at the time of delivery Megger products are free from manufacturing
or material defects which might considerably reduce their value or usability. This warranty
does not apply to faults in the software supplied. During the period of warranty, Megger
agree to repair faulty parts or replace them with new parts or parts as new (with the same
usability and life as new parts) according to their choice.

This warranty does not cover wear parts, lamps, fuses, batteries and accumulators.

Megger reject all further claims under warranty, in particular those from consequential
damage. Each component and product replaced in accordance with this warranty
becomes the property of Megger.

All warranty claims versus Megger are hereby limited to a period of 12 months from the
date of delivery. Each component supplied by Megger within the context of warranty will
also be covered by this warranty for the remaining period of time but for 90 days at least.

Each measure to remedy a claim under warranty shall exclusively be carried out by
Megger or an authorized service station.

This warranty does not apply to any fault or damage caused by exposing a product to
conditions not in accordance with this specification, by storing, transporting, or using it
improperly, or having it serviced or installed by a workshop not authorized by Megger. All
responsibility is disclaimed for damage due to wear, will of God, or connection to foreign
components.

For damage resulting from a violation of their duty to repair or re-supply items, Megger
can be made liable only in case of severe negligence or intention. Any liability for slight
negligence is disclaimed.

Since some states do not allow the exclusion or limitation of an implied warranty or of
consequential damage, the limitations of liability described above perhaps may not apply
to you.

4
Contents

Contents

Consultation with Megger ............................................................................................... 3

Terms of Warranty ........................................................................................................... 4

Contents ........................................................................................................................... 5

1 Safety Instructions ........................................................................................... 8

1.1 General Notes .................................................................................................... 8
1.2 General Safety Instructions and Warnings.........................................................9

2 Technical description ....................................................................................11

2.1 Description .......................................................................................................11
2.2 Technical data ..................................................................................................13
2.3 Displays and controls .......................................................................................21

3 Putting the test van into operation ...............................................................25

3.1 Securing the area .............................................................................................25
3.2 Electrical connection ........................................................................................26
3.2.1 Connection equipment .....................................................................................27
3.2.2 Connection of the earth cable ..........................................................................28
3.2.3 Connection of the FU cable (auxiliary earth) ....................................................29
3.2.4 Connection to the test object ............................................................................30
3.2.4.1 Using the HV connection cable ........................................................................30
3.2.4.2 Using the Teleflex LV cable (optional) .............................................................34
3.2.4.3 Using the MFM/HVB connection cable (optional) ............................................35
3.2.5 Connecting the power cable .............................................................................36
3.2.6 Connection of the external safety device (optional) .........................................38
3.3 Use of USB accessories...................................................................................40
3.4 Setting up switch-on standby ...........................................................................41
3.5 Switching on the test van .................................................................................42

4 Operating the test van in general .................................................................43

4.1 Switching high voltage on and off ....................................................................43

5 Operating the Teleflex VX ..............................................................................44

5.1 Screen layout ...................................................................................................44
5.2 Basics of control ...............................................................................................46

5.3 Quick selection of operating modes – .....................................................49

5.4 Phase selection - .....................................................................................50

5.5 History database - ....................................................................................52

5.6 System settings - .......................................................................................56

5.6.1 Data menu - ................................................................................................58
5.6.2 Basic settings - ...........................................................................................59

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 Contents

5.6.3 Administration menu - (administration password required) ........................61

5.6.3.1 Backing up and updating data - | ........................................................62
5.6.3.2 User administration - ..................................................................................63
5.6.3.3 Connection Lead Calibration - .....................................................................64

6 Conducting measurements ...........................................................................65

6.1 Good to know … ...............................................................................................65
6.1.1 Propagation velocity .........................................................................................65
6.1.2 Pulse width .......................................................................................................66
6.1.3 Typical TDR reflectograms ...............................................................................67
6.2 Standard functions ...........................................................................................68
6.3 Systematics of cable fault location ...................................................................71
6.4 Insulation measurement ...................................................................................72
6.4.1 Insulation testing with an external insulation tester ..........................................72
6.4.2 Insulation testing with internal ISO module ......................................................73
6.4.3 Measurement of insulation resistance and test object capacitance .................73
6.4.4 Time-dependent measurement of resistance - ..........................................76
6.5 Cable testing - ...........................................................................................78
6.6 Sheath test and sheath fault pinpointing (optional) ..........................................82
6.6.1 Testing a cable sheath - ............................................................................83
6.6.2 Pinpointing a sheath fault - .......................................................................85
6.7 Pulse reflection measurement (TDR) - .....................................................87
6.8 Pre-location of high-resistance cable faults - ..........................................90
6.8.1 Arc reflection measurement (ARM) - .........................................................90
6.8.1.1 ARM measurement up to 12 kV (with Surge Unit 3/6/12 kV) ...........................92
6.8.1.2 ARM measurement up to 50 kV (double surge unit) ........................................94
6.8.2 Voltage decoupling (DECAY) - .................................................................96
6.8.3 Current decoupling (ICE) - ........................................................................98
6.8.3.1 ICE prelocation up to 12 kV (with Surge Unit 3/6/12 kV) .................................98
6.8.3.2 ICE prelocation up to 50 kV or 80 / 100 kV (optional) ....................................100
6.8.4 Three-phase current decoupling (optional) - ...........................................103
6.8.5 ARM burning with the 15 kV burn down unit (optional) - ..........................106
6.9 Burning ...........................................................................................................108
6.9.1 Burning up to 110 kV (with internal voltage source) ......................................108
6.9.2 Burning with the 15 kV burn unit (optional) ....................................................109
6.10 Fault pinpointing .............................................................................................110
6.10.1 Surge pinpointing up to 12 kV (with surge unit 3/6/12 kV) .............................110
6.10.2 Surge pinpointing up to 50 kV ........................................................................112
6.10.3 Surge pinpointing up to 80/100 kV (optional) .................................................113
6.10.4 Line and fault location with the audio frequency generator............................114
6.11 Dielectric diagnosis (optional) ........................................................................117
6.11.1 Withstand voltage diagnosis ..........................................................................118
6.11.2 Tan delta step test ..........................................................................................122

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Contents

6.11.2.1 Preparing the step test ...................................................................................122

6.11.2.2 Performing the step test .................................................................................125
6.11.2.3 Automatic evaluation of the test results .........................................................129
6.11.2.4 Setting your own evaluation criteria ...............................................................130
6.11.2.5 Manual evaluation of the test results ..............................................................132
6.12 Partial discharge diagnosis (optional) ............................................................135
6.13 Sheath test and sheath fault location with the MFM 10-M / HVB 10-M
(optional).........................................................................................................136
6.14 Completing the work .......................................................................................137

7 Exporting and processing measurement data ..........................................138

8 Troubleshooting ...........................................................................................139

9 Care and Maintenance .................................................................................142

9.1 Required maintenance by a service workshop ..............................................142
9.2 Maintenance work you can carry out yourself ................................................142

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 Safety Instructions

1 Safety Instructions

1.1 General Notes

Safety precautions This manual contains basic instructions for the commissioning and operation of the device
/ system. For this reason, it is important to ensure that the manual is always available to
the authorised and trained operator. He needs to read the manual thoroughly. The
manufacturer is not liable for damage to material or humans due to non-observance of
the instructions and safety advices provided by this manual.

Locally applying regulations have to be observed!

Labelling of safety The following signal words and symbols are used in this manual and on the product itself:
instructions
Signal word / Description
symbol
DANGER Indicates a potential hazard which will result in death or serious
injury if not avoided.
WARNING Indicates a potential hazard which may result in death or
serious injury if not avoided.
CAUTION Indicates a potential hazard which may result in moderate or
minor injury if not avoided.
NOTICE Indicates a potential hazard which may result in material
damage if not avoided.
Serves to highlight warnings and safety instructions.
As a warning label on the product it is used to draw attention to
potential hazards which have to be avoided by reading the
manual.
Serves to highlight warnings and safety instructions that
explicitly indicate the risk of an electric shock.

Serves to highlight important information and useful tips on the

operation of the device/system. Failure to observe may lead to
unusable measurement results.

Working with products It is important to observe the generally applicable electrical regulations of the country in
from Megger which the device will be installed and operated, as well as the current national accident
prevention regulations and internal company directives (work, operating and safety
regulations).

After working on the system, it must be voltage-free and secured against reconnection as
well as having been discharged, earthed and short-circuited.

Use genuine accessories to ensure system safety and reliable operation. The use of other
parts is not permitted and invalidates the warranty.

8
Safety Instructions

Operating staff The system may only be installed and operated by an authorised electrician. DIN VDE
0104 (EN 50191), DIN VDE 0105 (EN 50110) and the German accident prevention
regulations (UVV) define an electrician as someone whose knowledge, experience and
familiarity with the applicable regulations enables him to recognise potential hazards.

Anyone else must be kept away!

Repair and Repair and maintenance work has to be carried out by Megger or authorised service
maintenance partners using original spare parts only. Megger recommends having the system tested
and maintained at a Megger service centre once a year.

Megger also offers its customers on-site service. Please contact your service centre if
needed.

Electromagnetic This device is designed for industrial use. When used at home it could cause interference
radiation to other equipment, such as the radio or television.

The interference level from the line complies with the limit curve B (living area), the
radiation level complies with the limit curve A (industrial area) according to EN 55011.
Given that living areas are sufficiently far away from the planned area of operation
(industrial area), equipment in living areas will not be impaired.

1.2 General Safety Instructions and Warnings

Intended application The operating safety is only guaranteed if the delivered system is used as intended (see
page 11). Incorrect use may result in danger to the operator, to the system and the
connected equipment.

The thresholds listed in the technical data may not be exceeded under any circumstances.

Operation in traffic To ensure safety for operators and traffic, the country-specific regulations must be
environment observed.

Five safety rules

The five safety rules must always be followed when working with HV (High Voltage):
1. De-energise
2. Protect against re-energising
3. Confirm absence of voltage
4. Earth and short-circuit
5. Cover up or bar-off neighbouring energised parts

Using cardiac pacemaker / defibrillator

Physical processes during operation of high voltage may endanger
persons wearing a cardiac pacemaker or defibrillator when near these
high voltage facilities.

9
 Safety Instructions

Fire fighting in electrical installations

• According to regulations, carbon dioxide (CO2) is required to be
used as extinguishing agent for fighting fire in electrical
installations.
• Carbon dioxide is electrically non conductive and does not leave
residues. It is safe to be used in energized facilities as long as
the minimum distances are maintained. A CO2 fire extinguisher
must be always available within electrical installations.
• If, contrary to the regulations, any other extinguishing agent is
used for fire fighting, this may lead to damage at the electrical
installation. Megger disclaims any liability for consequential
damage. Furthermore, when using a powder extinguisher near
high-voltage installations, there is a danger that the operator of
the fire extinguisher will get an electrical shock from a voltage
arc-over (due to the powder dust created).
• It is essential to observe the safety instruction on the
extinguishing agent.
• Applicable is DIN VDE 0132.

Objects should not be placed on or lent against the heater, nor pushed
between the heater and wall.
Do not cover the air exit or leave any combustible material in close
vicinity to the heater.

WARNING
Dangers when working with high voltage
Working on high voltage systems and equipment – especially in non-
stationary operation – requires particular care and safety-conscious
action on the part of test personnel. VDE regulations 0104 on setting up
and operating electrical test systems, as well as EN 50191 and national
standards and regulations must be strictly adhered to.
• The System R 30 generates a dangerous voltage of up to 110 kV
during measurement operation. This is supplied to the test object via
a high-voltage cable.
• The test system may not be operated without supervision.
• Never fail to use safety equipment or put it out of operation.
• Operation requires minimum two people whereas the second person
must be able to activate the emergency switch in case of danger.
• To prevent dangerous charge accumulation, earth all metal parts in
the vicinity of the high voltage equipment.

WARNING
Peripheral devices
Please follow the safety instructions of the peripheral devices (e.g.
heater) installed in the system environment. For all peripheral devices
provided by Megger, the instructions manual is included in the scope of
delivery. Megger is not liable for damage to material or humans due to
misuse of these devices.

10
Technical description

2 Technical description

2.1 Description

Concept The powerful System R 30 three-phase test van combines the proven individual devices
of the Megger product range in almost any configuration combination and is suitable for
fast, simple and cable-gentle fault location on power cables. Optionally equipped with
powerful VLF test equipment and advanced diagnosis system, the system can also be
used for standard-compliant cable tests and partial discharge diagnosis.

The central component of the system is the proven Teleflex VX, via which both the
operating mode and the phases are selected. Depending on the selected operating mode,
the required individual devices are provided with mains voltage and the HV path is
switched. All individual devices of the test van are integrated in a control and safety
concept that has been adapted to the requirements of cable testing and fault location.

Features The System R 30 test van offers the following features:

• Modular and thus fail-safe system
• The highest safety standards
• Mains and generator operation
• Depending on the configuration, access to all state-of-the-art cable testing
systems and methods
• DC test voltage, up to 110 kV (optional: 150 kV)
• Surging for prelocation and pinpointing, up to 50 kV (100 kV optional)

Equipment variants Each System R 30 test van has certain basic equipment that essentially comprises the
following components:
• Connectors (HV connection cable, earth cable)
• motor switch for operating mode switching, 110 kV
• Combined discharge and earthing switch, 110 kV
• Control panel
• DC high voltage source, 110 kV
• Teleflex VX reflectometer (central operating unit for selecting the operating
modes and for recording, displaying and storing measurement data)
• Surge unit 3/6/12 kV
• 25/50 kV surge circuit
• ARM filter
• ARM double surge unit (for ARM prelocation up to 50 kV)
• Single-phase current decoupling (optional: three-phase current decoupling)
• Test van accessories (which include, among other things, spare fuses and the
SF6 filling unit H902)

11
 Technical description

In addition to this basic equipment, the test van can include a selection of the following
optional components:
• VLF CR-54 kV test attachment
• VLF CR-70 kV test attachment
• Test and diagnosis module TDM 45 / TDM 4540
• Test and diagnosis module TDM 62 / TDM 6260
• Partial discharge measuring system PDS 60(-HP) / PDS 62-SIN
• 15 kV burn unit
• ISO module for insulation testing
• Sheath test and fault location system (MFM 10-M / HVB 10-M), including its own
cable reel
• Audio frequency generator (FLG 200)
• Surging with up to 80 kV or 100 kV (incl. current decoupling)
• Three-phase current decoupling up to 50 kV
• External safety device, including cable reel
• Teleflex LV cable reel

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Technical description

2.2 Technical data

The test van itself is defined by the following parameters:

Parameter Value
Mains voltage 230 V (+6%, -10%), 50 / 60 Hz
Connection via isolating transformer (5 kVA)
Power supply 5 kVA (continuous load)
HV switch Gas-insulated, suitable for voltages up to
110 kV
Discharge capacity 10 µF at 110 kV
HV connectors 3 x 1-phase or 1 x 3-phase
HV connection cable, 50 m
LV connectors 1 x 3-phase LV connection cable, 50 m
(optional)
Power supply connectors / safety Power cable, 50 m (incl. matching isolating
transformer)
Earth cable, 50 m
Auxiliary earth connection cable (FU), 10 m
External safety device connection cable, 50 m
(optional)
Interfaces External sockets (for external Insulation
resistance tester, max. 1000 V)
Time Domain Reflectormeter
(Teleflex VX)
• Display 15" touch screen, 1980 x 1020
• Operating modes Symmetric/asymmetric refl ection
measurement, differential and comparative
measurement, IFL (for intermittent faults)
• Amplification Default : 0 … 100%;
ProRange: >22 dB
• Measuring range 20 m … 1,280 km (250 ns … 16 ms)
(at v/2 = 80 m/μs)
• Resolution 0,1 m
• v/2 range 10 ... 149.9 m/μs
• NVP range 0.067 … 1
• Accuracy 0.1% of measurement range
• Data rate 533 MHz
• Measuring dynamic >80 dB
• Pulse width 20 ns … 10 μs
• Pulse amplitude 50, 150 V
Testing with DC voltage
• Voltage range 0 to 110 kV
• Nominal current 5 mA
• Short-circuit current 290 mA

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 Technical description

Parameter Value
Surge energy
• Surge unit 3/6/12 kV See technical data of
Surge Unit 3/6/12 kV
• 25/50 kV surge circuit 2500 J
• 80 kV surging (optional) 1600 J or 3200 J
• 100 kV surging (optional) 2000 J
ISO module (optional)
• Test voltage <6 V, 500 V, 1000 V
• Resistance measuring range 1 Ω to 2 kΩ (with <6 V)
1 kΩ to 2 GΩ (with 500 V)
1 kΩ to 2 GΩ (with 1000 V)
• Capacitance measuring range 0 to 20 μF (resolution 0.1 μF)
(only with 500 V or 1000 V)
• Trend measurement Up to 15 minutes
(only with 500 V or 1000 V)
VLF CR-54 kV test attachment
(optional)
• Voltage wave shape Cosine square wave (0.1 Hz)
• Voltage range 0 to 54 kV
• Maximum load capacitance 5 μF@54 kV, 8 μF@36 k, 21 μF@18 kV
VLF CR-70 kV test attachment
(optional)
• Voltage wave shape Cosine square wave (0.1 Hz)
• Voltage range 0 to 70 kV
• Maximum load capacitance 5 μF@70 kV, 7.7 μF@54 kV,
13.9 μF@36 kV, 34.7 μF@18 kV
Audio frequency generator (FLG)
(optional)
• Frequencies 0.491 kHz, 0.982 kHz, 8.440 kHz (customer-
specific frequencies are possible)
• Output power 200 W (models 50 W or 10 W are available
as external devices)
15 kV burn unit (optional) See the enclosed operating manual
MFM 10-M sheath fault locator See the enclosed operating manual
(optional)
HVB 10-M high voltage measuring See the enclosed operating manual
bridge (optional)
Operating temperature -20 °C to +55 °C
Storage temperature -25 °C to +60 °C
Operating humidity 93% at 30 °C (non-condensing)
Weight of the HV range Approx. 1050 kg (depending on the
equipment)

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Technical description

Technical data of the Depending on its configuration, the Surge Unit 3/6/12 kV is specified by the following
Surge Unit 3/6/12 kV parameters:
Parameter Value
Surge voltage levels 0 … 3 kV, 0 … 6 kV, 0 … 12 kV
Surge rate
• adjustable ca. 0.8 … 8 s
• electronically controlled ≥4.5 s (3 kV), ≥2.5 s (6 kV), ≥4.0 s (12 kV)
Surge energy (see also the diagram 1000 J in standard version or
below) 2000 J with option „double surge energy“
Kurzschlussstrom 155 mA
Power consumption max. 2,000 VA

Depending on the configuration and the selected voltage range the Surge Unit 3/6/12 kV
provides the following surge energy:

15
 Technical description

Technical data of the The optional TDM 45 / TDM 4540 test attachment is defined by the following parameters:
TDM 45 / TDM 4540
test attachment Parameter Value
(optional) Output voltage

• Sine wave 2 … 32 kVRMS / 45 kVPEAK

• DC ±2 … 45 kV
• Square wave ±2 … ±45 kV
• Cosine rectangular (optional) ±3 … 40 kV
• DAC (Damped AC) (optional) ±3 … ±40 kV
Max. source output current 12 mARMS (at nominal voltage)
Leakage current measurement (Rectangular, VLF-CR and DC operation)
• Display area 0 … 20 mA
• Resolution 10 μA
Frequency
• Sine wave / square wave voltage 0.01 Hz to 0.1 Hz
• Cosine rectangular voltage 0.1 Hz
• DAC voltage 20 Hz to 500 Hz
Testable load capacitance (see also diagrams below)
• Sine wave voltage 0.6 μF at 45 kV / 0.1 Hz
• Square wave voltage 0.6 μF at 45 kV / 0.1 Hz
• DC voltage 5 μF at 45 kV
• Cosine rectangular voltage / 4.8 μF at 40 kV
DAC voltage
• Maximum load capacitance 10 μF at reduced voltages and frequencies
Internal tan delta (optional)
• Measurement range 10-3 to 100
• Accuracy (at a load capacity 1 x 10-3 or 1%
>20 nF)
• Resolution 1 x 10-4
Pulse rate in sheath pinpointing 0.5:1 / 1:2 / 1:3 / 1:4 / 1.5:0.5
mode (in seconds)

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Technical description

The following diagram applies to tests with a sine wave voltage and illustrates the
dependency of the test frequency on the capacity of the load connected and the test
voltage set. If a test frequency cannot be used due to the capacity limitations specified
here, the frequency is automatically adapted and the user is informed of this.

In cosine rectangular or DAC operation (optional), the following load diagram applies
analogously 1:
Cload / µF

U / kV

1Only applies between -25 and 45 °C. In the temperature range from 45 °C to 55 °C, at
40 kV the power is reduced to 80%.

17
 Technical description

Technical data of the The optional TDM 62 / TDM 6260 test attachment is defined by the following parameters:
TDM 62 / TDM 6260
test attachment Parameter Value
(optional) Output voltage

• Sine wave 2 … 44 kVRMS / 62 kVPEAK

• DC ±2 … 62 kV
• Square wave ±2 … ±62 kV
• Cosine rectangular (optional) ±3 … 60 kV
• DAC (Damped AC) (optional) ±3 … ±60 kV
Max. source output current 23 mARMS (at nominal voltage)
Leakage current measurement (Rectangular and DC operation)
• Display area 0 … 20 mA
• Resolution 10 μA
Frequency
• Sine wave / square wave voltage 0.01 Hz to 0.1 Hz
Testable load capacitance (see also diagram below)
• Sine wave voltage 1.0 μF at 62 kV / 0.1 Hz
• Square wave voltage 1.0 μF at 62 kV / 0.1 Hz
• DC voltage 5 μF at 62 kV
• Cosine rectangular voltage 4,4 μF at 60 kV
• DAC voltage 4,6 μF at 60 kV
• Maximum load capacitance 10 μF at reduced voltages and frequencies
Internal tan delta (optional)
• Measurement range 10-4 … 100
• Accuracy (at a load capacity 1 x 10-4
>20 nF)
• Resolution 1 x 10-5
Pulse rate in sheath pinpointing 0.5:1 / 1:2 / 1:3 / 1:4 / 1.5:0.5
mode (in seconds)

18
Technical description

The following diagram applies to tests with a sine wave voltage and illustrates the
dependency of the test frequency on the capacity of the load connected and the test
voltage set. If a test frequency cannot be used due to the capacity limitations specified
here, the frequency is automatically adapted and the user is informed of this.

Cload / µF

U / kVrms
In cosine rectangular or DAC operation (optional), the following load diagram applies
analogously 2:
Cload / µF

U / kV

2Only applies between -25 and 45 °C. In the temperature range from 45 °C to 55 °C, at
60 kV the power is reduced to 80%.

19
 Technical description

Technical data of other

measurement The technical data of additional measurement equipment (for example,
equipment / peripherals digiPhone+, PDS 60, Tan Delta test attachment) and peripherals (for
example, generator system) contained in the test van can be found in the
respective operating instructions.

20
Technical description

2.3 Displays and controls

Control console All the components that are required to control, test and monitor the measurements are
installed on the control console. The following figure shows an example of the equipment
of the control console at a typical configuration level:

Component Description

MFM 10-M / HVB 10-M (optional)

Control panel

Teleflex VX

Surge unit 3/6/12 kV

15 kV burn unit (optional)

21
 Technical description

Teleflex Vx The Teleflex VX is the central operating unit of the test van and has the following operating
elements:

Element Beschreibung

On/off switch

Rotary encoder

22
Technical description

Control panel The control panel has the following controls and displays:

Element Description

“HV Interlock” key switch (see page 43)

EMERGENCY OFF switch
Pressing the EMERGENCY STOP button will shut off the high voltage
immediately and discharge the test object before earthing the HV output.
The plug sockets in the control room will still be live.
External sockets
Residual voltage indicator (optional)
The residual voltage indicator signals the voltage that is currently present at
the HV output of the system. Systems which are equipped with a test and
diagnosis module (TDM) can also have a second residual voltage indicator
(always located on right of actual indicator). The voltage that is currently
present at the single-phase diagnosis output is signalled on this.
Main switch

„HV Off“ button

„HV On“ button

23
 Technical description

Surge unit 3/6/12 kV The surge unit 3/6/12 kV has the following controls and displays:

Element Description

Range selector

Rotary knob to adjust the voltage

kV meter to display the actual charging voltage of the internal surge
capacitors
Rotary knob to adjust the surge rate

On/off switch

„HV On“ button

24
Putting the test van into operation

3 Putting the test van into operation

Applicable guidelines The guidelines for implementation of occupational safety when operating a test system /
test van often differ between one network operator and another and it is not uncommon
for national regulations (like, i.e. the German BGI 5191) to be used as well.

Inform yourself of the guidelines applicable in the area of operation beforehand, and
comply with the specified rules for work organization and for implementing the test system
/ test van.

3.1 Securing the area

The following steps must be taken to adequately secure the area and the test van:
Step Action
1 Place the test van so that it is level (slope <10%) and near the access to the
test object, taking into consideration its load and external dimensions. Verify
that the test van is in a stable position.

WARNING
Never place the test van directly over the route of the cable to
be tested!

2 Use the parking brake to secure the test van from rolling away and place stop
blocks on the wheels if required.
3 Secure the area according to regional regulations using barricades, warning
signs and cable bridges.

25
 Putting the test van into operation

3.2 Electrical connection

The following figure shows the simplified connection diagram:

230 V (+6%, -10%),

50 / 60 Hz

Station earth or other suitable

foundation earth electrode

WARNING
Follow the specified connection sequence.
The electrical connection must be carried out in the sequence shown in
the figure. Connection to the mains occurs last.
Disconnection is to proceed in reverse order.

Connection of the earth cable (see page 27)

Connection of the FU cable (auxiliary earth) (see page 29)

Connection to the test object (see page 30)

Connection to the mains (see page 35)

Connection of the external safety device (optional) (see page 38)

26
Putting the test van into operation

3.2.1 Connection equipment

Type and arrangement of the connection equipment may differ depending on

the type of vehicle and the configuration.

Usually the equipment includes the cable reels shown in the following figure:

Part Description

Cable reel of FU cable

Cable reel of earth cable

Power cable reel

Teleflex LV cable reel (optional)
for three-phase reflection measurements with low voltage
Cable reel of ext. safety device (optional)

HV connection panel

High voltage cable reel

27
 Putting the test van into operation

3.2.2 Connection of the earth cable

• The test van should never be operated without the earth cable being
connected. This applies in respect of mains operation as well as
generator operation. The earth cable establishes the connection
between the system and the protective earth and ensures that the
WARNING entire system is touch-proof.
• The test van should be operated only on earthing systems or single
earth electrodes with transition resistances <2 Ω.
• The protective earth (earth cable) and system earth (screen of the HV
cable) must be connected so that no unacceptable voltage difference
may arise between the protective earth (PE) and neutral
conductor (N).
• For TT networks, there is no connection between the neutral
conductor (N) and protective earth (PE) in the station. This connection
must be created for the measurement with a suitable cable.

Proceed as follows to connect the earth cable:

Step Action
1 Release the brake of the earth cable reel.
2 Unwind the cable and connect it to the station earth or other suitable
foundation earth.
3 Clamp one of the contact sleeves attached to the cable at intervals of 5 m
under the connecting clamp next to the cable reel.

4 Secure the cable reel brake again.

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Putting the test van into operation

3.2.3 Connection of the FU cable (auxiliary earth)

Proceed as follows to connect the FU cable (auxiliary earth) to monitor the voltage-time
integral and fault voltage:
Step Action
1 Unwind the FU cable.
2 Place the earth spike into the ground in the immediate vicinity of the test van
and attach the FU cable to it.

3 Connect the other end of the cable to the connector on the FU cable reel.

If after switching the test van on high voltage operation is blocked due to poor
earthing conditions despite the connected auxiliary earth, the measures may
correct the situation:
• Try inserting the earthing rod in other locations which may be more suitable.
In heavily built-up areas, the gaps between the concrete slabs can be used,
for example.
• Use water to moisten the location where the earthing rod has been inserted.
• Attach the auxiliary earth to a foundation earth (e.g. a lightning protection
system). Do not use the same foundation earth to which you have already
connected the main earthing cable.

29
 Putting the test van into operation

3.2.4 Connection to the test object

• Before connecting to the test object or before adjusting the wiring in

the HV room of the test van, the five safety rules (see page 9) must
be applied.
• Those phases of the cable under test which are not being tested must
WARNING be short-circuited and earthed.
• Install protective equipment (such as railings, chains or bars) to block
access to the hazard zone and prevent the risk of touching live parts.
• Because the voltage applied to the device under test can exhibit
values that represent a shock hazard, all cable ends must be shielded
in accordance with VDE 0104 to prevent contact. Make sure that all
cable branches are taken into account.

3.2.4.1 Using the HV connection cable

Application For almost all operating modes (exceptions are described in the next sections), the test
van is connected with the test object via standard HV connection cable.

Procedure Perform the following steps to establish a connection between the HV output and the test
object:
Step Action
1 Make sure that used cable reel is not connected to one of the HV outputs of
the system and hence is freely rotatable.
2 Release the brake of the HV cable reel.
3 Unwind the HV connection cable.
4 Connect the screen of the HV connection cable to the earthed screen of the
test object (operational earth).
5 Use a suitable terminal to connect the inner conductor of the HV cable to the
test object phase to be tested.
6 If required, also connect the remaining two connection cables with the test
object.
Connection cables which are not required for the current measurement task,
are to be short-circuited at the metal bar next to the cable reel.
7 On the system side, connect these cable reels which are connected to the
test object to the appropriate HV output of the HV connection panel. (see
notes on the next pages).
8 Secure the brake of the HV cable reel again.

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 Putting the test van into operation

System-side In vehicles without special options, the electrical connection between the HV output and
connection in vehicles the cable reels must be made as follows:
with standard version

Special features in In vehicles with an additional test and diagnosis module (TDM) and a partial discharge
vehicles with test and measurement system (PDS), the electrical connection between the HV outputs and the
diagnosis module cable reels must be made as follows depending on the operating mode:
(TDM)
Partial discharge diagnosis with integrated coupler:

31
 Putting the test van into operation

Partial discharge diagnosis with removable coupler:

Tan Delta measurement:

At the test object side, the cable shield of the HV connecting cable must be connected via
the HVCC adapter.

32
Putting the test van into operation

All other operating modes (including three-phase testing with VLF SIN and VLF CR
voltage:

Special features The connection of the cable reels to the patch panel in the HV area of the test van must
with vehicles be adjusted to correspond to the desired operating mode when switching between normal
with the 80/100 kV operation and 80/100 kV surging operation.
surging option During the 80/100 kV surging operation, the connection to the test object must of
necessity be via cable reel HV3.

Normal operation 80/100 kV surging

(50 kV surging)

“80/100kV Surging” HV output

Connecting cable from separate 100 kV surge switch
“80/100kV Surging” earthed parking position

33
 Putting the test van into operation

3.2.4.2 Using the Teleflex LV cable (optional)

Application The Teleflex LV cable can be used exclusively for specially designated LV pulse reflection
methods of the Teleflex VX. In all other operating modes, the test object must be
connected using the HV connection cable.

Procedure Perform the following steps to connect the LV cable to the test object:
Step Action
1 If the connection cable coming from the reflectometer is connected to the
socket of the cable reel body, this connection must be disconnected before the
cable can be unwound.

2 Unwind the LV cable.

3 Connect the unwound LV cable with the four-core adapter cable pre-
assembled for the connection to the test object.
4 Use appropriate connection accessories to connect the individual phases of
the LV cable with the phases of the test object and connect the operational
earth (red terminal) to the earthed screen of the test object.

When connecting, make sure that the four wires are run as uniformly
as possible to each other (ideally twisted) and are not separated from
each other until just before the actual connection point. This ensures
that all three phases have similar impedance values.
Labeling of the phases must be taken into account when making the
connection in order for it to be possible to properly assign the
measurement results to the respective phases.

5 Reconnect the connection cable coming from the reflectometer with the socket
on the cable reel.

34
Putting the test van into operation

3.2.4.3 Using the MFM/HVB connection cable (optional)

Application The special MFM/HVB connection cable is connected directly to the sheath fault location
system MFM 10-M or the high voltage bridge HVB 10-M respectively and is used
exclusively for the operating modes of these devices.

Procedure
For detailed instructions for the connection to the test object, please read the
operating manual of the MFM 10-M or HVB 10-M respectively.

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 Putting the test van into operation

3.2.5 Connecting the power cable

WARNING
Danger from electric shock
If the object under test and the mains power supply are connected to
different earthing systems which are not linked to each other, potential
equalisation has to be established during operation of the test van (using
a connection cable with a cross section of at least 16 mm2 Cu). Good
earthing conditions are extremely important!

Procedure Proceed as follows to connect the test van to the mains power supply:
Step Action
1 Release the brake of the mains cable reel.
2 Release the anti-roll latch on the outside of the cable drum housing by
pulling the metal bar outward.
To lock the anti-roll latch before winding the drum back up, press on the
round screw head.

3 Unwind the mains supply cable.

CAUTION
The mains cable drum must always be completely unrolled!

36
 Putting the test van into operation

Step Action
4 Connect the cable to a mains power outlet.

CAUTION
Only approved (VDE/IEC or corresponding national
regulations) intermediate connections are to be used for the
connection to mains sockets that do not fit the pre-
assembled plug or for direct connection to the low-voltage
cable!

Result: The two signal lamps IN and OUT on the mains connection system
NAS 60-3 should now light up, indicating that the input voltage is within the
permissible range. If this is not the case, check the mains supply and the
fuses in the NAS 60-3 (see page 139).

4 Secure the cable drum brake again.

Operation via If there is no possibility to tap mains power in the immediate vicinity of the deployment
generator or battery location, the measuring system can also be operated via an adequately dimensioned
power supply (optional) generator system or battery voltage supply.

An integrated battery power supply provided Megger automatically takes over the supply
of the measuring system if the test van has not been connected to mains voltage.

The generator systems provided Megger are typically vehicle engine driven systems,
which must be commissioned manually if necessary. To do this, the vehicle must be put
into neutral, the generator switched on and, if necessary, the engine speed must be
regulated. The exact procedure differs depending on the generator and vehicle model.

When the generator is in operation, the system automatically draws its operating voltage
from the generator. This also applies if the test van is connected to the mains power
supply.

For detailed information on the handling, specification and safety of the

systems provided, refer to the manufacturer's product information.

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 Putting the test van into operation

3.2.6 Connection of the external safety device (optional)

Purpose Using the external safety device, the status of the system can be indicated outside the
test van and the HV processing can be interrupted or blocked using the EMERGENCY
OFF switch and key switch.

Description The following figure shows the optional external safety device:

Part Description
Green signal light
Lights up when the system is switched on but not in high voltage operation.
Red signal light
Lights up as soon as high voltage can be generated. All discharge and
earthing devices are open and the test object must be treated as live.
HV interlock key switch

High voltage unlocked

High voltage locked. In this position, the key can be removed

and the system secured against unauthorised high-voltage
operation.
EMERGENCY OFF switch
Pressing the EMERGENCY STOP button will shut off the high voltage
immediately and discharge the test object before earthing the HV output. The
plug sockets in the control room will still be live.

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 Putting the test van into operation

Connection of the Proceed as follows to connect the external safety device:

external safety device
Step Action
1 If the external safety device connection cable is provided on a cable drum, first
disconnect the system from the cable drum.

2 Unroll the connection cable.

3 Place the external safety device so that it is accessible and visible near the
test van, and connect the connection cable to the appropriate socket.
4 If necessary, reconnect the connection cable coming from the system to the
socket on the cable drum.

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 Putting the test van into operation

3.3 Use of USB accessories

CAUTION
Risk of interference
To prevent malfunction of or even damage to the Teleflex VX, observe
the following instructions:
• Do not use extension cables when connecting USB accessories.
• During HV operation, no loose USB connection cables may be
inserted into the USB ports of the Teleflex.

The Teleflex VX has two Type-A USB ports to which the following accessories can be
connected:
Class Description
Input devices For convenient data entry, both corded and cordless keyboards and
mice can be connected.
Depending on whether a hardware mouse and/or keyboard is
connected, the on-screen keyboard and the mouse pointer can be
activated / deactivated in the basic settings of the software (see page
59).
It is also possible to connect a wireless keyboard and/or mouse with
a suitable USB dongle.
USB mass For the import and export of measured data and reports, USB mass
storage storage (for example USB flash drive and external hard drives) can
be connected.
Printer For direct printing of measured data and reports, a printer can be
connected. However, the selection of compatible printers is limited by
the drivers installed on the system.
Before buying a new printer, please contact your Megger sales
partner for a list of supported devices.

40
Putting the test van into operation

3.4 Setting up switch-on standby

After the test van has been connected or a change made to the test object activation, the
connection cables must be led through the cable guide to the outside, as shown in the
following figure:

After the rear doors of the test van have been closed, it is ready to be turned on. Assuming
that the connection was established properly and good earthing conditions were ensured,
the conditions of the safety circuit are thus also fulfilled.

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 Putting the test van into operation

3.5 Switching on the test van

Switching on the test After the test van has been connected as prescribed, the control voltage can be switched
van on with the illuminated main switch on the control panel.

Safety circuits Directly after switching on the test van, the requirements of both safety circuits are
constantly monitored for deviations. In the event that all the requirements of safety
circuit I are fulfilled, the Teleflex VX is supplied with power and, without any further
presettings, a pulse reflection measurement via the optional Teleflex LV cable can be
carried out.
For high voltage operation, the requirements of safety circuit II must also be fulfilled, in
addition. Deviations from the requirements are indicated by the following messages on
the Teleflex VX display:
Message Cause SC I SC II
HV Unit disabled by One of the EMERGENCY OFF switches has
Emergency Off been activated.

Error ground Resistance between the vehicle chassis and

resistance surrounding ground (auxiliary earth) is too high
(>15 ±2 kΩ).

Input voltage out of The supply voltage is not within the permitted
range! range.

Voltage raise of Voltage-time integral between the vehicle

protective earth chassis and the surrounding ground is too high.
Check the quality of the connection to
protective earth and operational earth.
This message may also indicate that the test
van is directly above the fault position.

Door is open The rear door of the test van is open.

HV Unit disabled by High voltage operation has been disabled

Interlock Key using the key switch on the control panel.or
by means of the external safety device (see
page 38).

Cable shield not Resistance between the system earth and

grounded protective earth is too high (>10.5 ±2 Ω).

42
Operating the test van in general

4 Operating the test van in general

4.1 Switching high voltage on and off

Switching high If the requirements of both safety circuits have been met and the operating mode has
voltage on been started using menu item after setting the phases, the green illuminated “HV ON”
push-button on the control panel signals readiness for HV enabling.

Pressing the push-button makes the high voltage ready for switching on. The “HV ON”
push-button goes off and the red “HV OFF” button signals the new switching status.
High voltage is not yet being generated, but the earthing switches are open and all
individual devices which are needed for the operating mode are being supplied with
voltage.

If the green “HV ON” push-button is not pressed within 15 seconds, it goes off. In this
case the operating mode must be restarted before the high voltage can be enabled.

Switching high HV operation can be terminated at any time immediately by pressing the red illuminated
voltage off „HV OFF” button .

The HV devices are switched off and the test object is discharged. The discharge switch
as well as the delayed triggered earthing switch are gravity-operated, so that even in the
event of a power failure the safe discharging of the test van and the test object is
guaranteed.

The described discharge is also carried out in the following circumstances:

• Opening the rear doors
• Activating an EMERGENCY OFF switch
• Power failure

If the test van is equipped with the optional residual voltage indicator, the de-energised
status of the measuring circuit can also be verified on the analogue residual voltage
indicator as well. In operating modes where the voltage is generated by supplied
individual devices (e.g. MFM-10-M, Surge Unit 3/6/12 kV), the voltage will not be
displayed!

Locking high voltage The control panel is equipped with a key switch that can prevent switching on high
voltage. The switch can be set to the following positions:

High voltage unlocked.

High voltage locked. In this position, the key can be removed and the
system secured against unauthorised high-voltage operation.

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 Operating the Teleflex VX

5 Operating the Teleflex VX

5.1 Screen layout

The following figure shows the typical screen layout:

Segment Description
Traces for current measurement or loaded measurements. The display is
split up into a general overview (top) and in an enlarged section (bottom).
Current status messages and information on the next step required in the
test sequence.
Information on the states of the high voltage outputs. The symbols indicate
the following states:
The HV output has not been selected for the upcoming / running
measurement.
The HV output has been selected for the upcoming / running
measurement.
High voltage generation is switched off and the HV output is
discharged.
The resistor discharge is cancelled here. High voltage is active!

Voltage display bar graph

Blue bar: Set value
Red bar: Actual value

44
Operating the Teleflex VX

Segment Description
The display elements arranged in the lower area of the screen may contain
the following information:
• Set measurement parameters
• Current measurement values, which are continuously updated as the
measurement progresses
• Legend of traces currently shown in display (see page 54).

Information (such as, e.g. measurement values) which apply for a particular
trace only, is shown in the respective colour.
Selection menu (see page 46)

Current system state

The system is currently in standby.

Pulse reflection measurement currently under way.

The measurement was stopped and the traces frozen.

The device is in measurement operational readiness and waiting to

be triggered.
The user operating the system has successfully logged into the
administration menu (see page 61) and identified himself / herself as
administrator.
Current operating mode

Power source and parameters

Mains operation
Generator operation

45
 Operating the Teleflex VX

5.2 Basics of control

Selection menu Navigation within the menus is effected almost entirely from the circular selection menu:

Currently selected
Back to the next higher menu item
menu level

Selection switch Description of the

(green when active) currently selected menu
item
Language

Operation with rotary The Teleflex VX can be operated using the rotary encoder as follows:
encoder
• Select the required menu item
• Increase or decrease the value of a variable parameter
• Select an option from a selection list

• Call up the selected menu item

• Confirm the setting or the selection made

The four side menus are retrieved either by tilting the rotary encoder:

Quick selection of operating modes

Phase selection (see page 50)

Info page

History database (see page 52)

46
 Operating the Teleflex VX

Operation with mouse Operation using the mouse and keyboard is as follows:
and keyboard
• Select the required menu item
• Increase or decrease the value of a variable
parameter
• Select an option from a selection list

• Call up the selected menu item

• Confirm the setting or the selection made

Quick selection of operating modes

Phase selection (see page 50)

Info page

History database (see page 52)

47
 Operating the Teleflex VX

Operation using the If the device/system is equipped with a touch-sensitive display, then the software can also
touchscreen be operated just by using your fingers.

Briefly tapping on the buttons in the various menus, and tapping and holding the buttons
in isolated cases, allows the respective functions to be activated in the same way as the
rotary encoder control.

The four menus at the side can be opened by a swiping motion.

Quick selection of operating modes Phase selection (see page 50)

Info page History database (see page 52)

Whenever character strings need to be entered or changed, an on-screen keyboard

appears at the lower edge of the display:

If wanted, the touch functionality and the on-screen keyboard can be disabled in the basic
settings (see page 59). The latter is particularly useful, if a hardware keyboard is
connected.

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Operating the Teleflex VX

Dialog boxes A few settings, which require values to be entered, are not made directly using the
selection menu, but rather in a separate dialog box.

Date and time

Ok Cancel

Using and the user can switch back and forth between the individual buttons
in a dialog box. Each active button is then highlighted in white or it is surrounded by a red
frame. Whenever the selected button requires letters or digits to be entered the screen
keyboard automatically appears (touchscreen required), and it can then be used to make
the entries.

To close a dialog box, the corresponding button must be selected and then the rotary
encoder pressed.

5.3 Quick selection of operating modes –

Using the quick selection menu can be accessed (as well as closed) at any time.
The menu provides direct access to all the available operating modes.

49
 Operating the Teleflex VX

5.4 Phase selection -

Opening phase The selection menu for the phase(s) involved in the measurement opens automatically as
selection menu soon as an operating mode is entered. It can also be opened manually at any time via
.

Selecting the phases The desired phase can be marked for selection by turning the rotary encoder and then
selected or deselected by pressing it.

Option is active

Option is not active

The options that are displayed during phase selection and the number thereof that can be
selected at the same time depends on both the operating mode and the number and type
of cable reels.

Correcting the Immediately after at least one option has been selected, the recommended connection
connection situation situation for the current phase selection is shown on the left next to the selection window,
as shown in the example below.

It must be checked whether the connection to the test object that is shown corresponds
with the actual connection situation. If this is not the case, the electrical connection must
be adapted accordingly.

50
 Operating the Teleflex VX

Depending on the operating mode and the available cable reels, changes can also be
made to the connection schematic shown using the and buttons within the
technical permitted scope. In this way, for example, test object phases can be individually
connected / disconnected, the assignment between patch panel output and test object
phase can be changed, or bridges installed at the test object (for simultaneous testing of
multiple phases) can be added.

Confirming the phase The phase selection menu can only be closed once a valid selection has been made. By
selection closing the menu via , the active selection is confirmed. Until the actual start of the
measurement, the selection menu can be called up again and adjusted.

Make sure that the phase selection matches the actual connection situation!
Otherwise, the measuring data will be stored with incorrect phase details
whereupon the data will not be able to be correctly assigned afterwards.

Selecting the phase in Depending on the configuration of the system, the outputs LV (Teleflex LV cable), DIAG
systems with additional (output for the test and diagnosis module), and HV4 (output for 80/100 kV Surging mode)
system outputs may be present in the phase selection menu alongside outputs HV1 to HV3.

For the LV and DIAG outputs, the selected operating mode is the only determining factor
for which output is used to select the phase in the phase selection menu. This prevents
erroneous selections.

Systems with the option "80/100 kV Surging" are the only type of system in which the
selection of a certain HV output in ICE and surge operating modes has a direct influence
on the measurement parameters. If the system is connected via outputs HV1, HV2, or
HV3, the maximum surge level that can be selected is 50 kV. To operate at the 80/100
kV surge level, the system must be connected through the HV4 output.

If the actual connection status does not fulfil the prerequisites for 80/100 kV surge
operation (see page 33), the operating mode cannot be activated, and a corresponding
message is displayed.

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 Operating the Teleflex VX

5.5 History database -

Purpose Each conducted measurement is temporarily stored in the History database and it can be
retrieved from there again. This enables the user to access old traces and to compare
them with the current traces. The parameters under which the measurement was
conducted are also shown.

Browsing the history Via the history database can be called up at any time.
database
The measurement data records are organised by date in sub-directories.

After the desired month and then the desired day have been selected, the measurement
data records registered on this days can be searched through and retrieved.

Date and time of Measurement parameters

measurement Operating mode and results

Storage period Tested phases Comment

(see next page)

Via the list entry you can always return to the next directory level up.

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Operating the Teleflex VX

Via the list entry you can reach the search mask using which you can search for
particular operating modes and comment entries through the data records of the current
directory and all sub-directories.

If you are searching for both an operating mode and comment entry at the same time,
only those results which fulfil both criteria will be displayed.

Holding down the button will cause the search criteria to be discarded and all the data
records to be displayed again.

Storage period The default setting stores the measurement data for 90 days in the history database. The
following symbol indicates how long a measurement has already been stored:
Symbol Description
No The data record has been conducted just recently. An automatic deletion is
symbol not imminent.
The data record is either imported or permanently stored (see page 68).

Automatic deletion of the measurement data record is imminent (less than 5

days remain).

To prevent the imminent deletion of a specific measurement data record, it only needs to
be called up from the history database and permanently saved via the M menu item (see
page 68).

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 Operating the Teleflex VX

Managing data records If a data record or an entire folder is to be exported or deleted, it has to be selected first
using the rotary encoder and then has to be marked appropriately using .
Symbol Description
The data record or the folder (incl. all data records in it) is marked for
deletion.
The data record or the folder (incl. all data records in it) is marked for export.

Several data records within the folder have been marked for deletion.

Several data records within the folder have been marked for export.

The folder contains both data records marked for deletion and data records
marked for export.

After selection of the measurements the data deletion or export process must be
initiated in the data menu (see page 58). Otherwise the markings will expire the
next time the software is started up.

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Operating the Teleflex VX

Accessing To access curves and data from old measurements, first access the history database and
measurement data then use the rotary encoder to select the respective measurement from the directory
from the history structure. Briefly pressing the rotary encoder enables all the curves and measured data
database for this measurement to be loaded. To this end, the software proceeds as follows:

• If the operating mode currently selected is the same operating mode in which
the loaded measurement was recorded in, the accessed curves are shown
together with the currently recorded curves. This enables the results of different
measuring operations to be easily compared.
• If the current and the loaded measurement are not of the same operating mode,
the current measurement is automatically ended and only the loaded
measurement is displayed.
• If there are not enough free slots to display the loaded curves, the currently
recorded curves are overwritten. To avoid this, it is advisable to select curves
from the History database one by one (see below) so that you can assign them
individually to slots that are free or no longer needed.

If you want to repeat a test, you can use this function to first of all access the measured
dataset from the previous test from the history and then launch a new test with the same
test parameters. Because the curves from the previous test also remain on the display
after the new test has begun, you can conveniently compare these with those of the
current test.

The colour-coded legend on the bottom right edge of the screen provides information
relating to the measured values of the curves currently displayed.

Current and loaded curves can be differentiated between using the symbols in front of
them.
Symbol Description
Curves which were recorded during the measurement in progress.

Curves which have been accessed from the history database.

By Holding down the rotary encoder a context menu can be opened from which the
following special functions can be accessed:
• Add / edit a comment for the measurement
• Access special measurement data or only individual traces of this measurement
(possible in certain modes only)

55
 Operating the Teleflex VX

5.6 System settings -

The System menu can be access directly through the menu item when in the main
menu, and it contains the following menu items:
Menu
Description
item
Submenu for managing the measurement data (see page 58).

Basic settings (see page 59)

Default values can be adapted for nearly all the system settings. If user
management (see page 63) is active then each user can define and store
his / her own default values. These defaults are then loaded each time the
system starts or a user logs in.
The submenu contains the following items:
This menu item enables the current settings to be stored as default
values. Naturally, only the changes made during this session are
taken into consideration.

When saving the default values, note that all values that
have been changed since the last system start are saved,
which means that you might inadvertently save some
changes that you do not want. To be on the safe side, you
can first reload the current defaults (see below), make the
required settings and then save them.

This menu item can be used by the current user to reload his / her
stored default values.
This menu item restores the factory settings.

This menu item enables the default values for the current user to be
exported as XML files to the DefaultValues directory of the inserted
USB flash drive.
This menu item can be used to import defaults values that are stored
on an inserted USB flash drive into the system.
The imported values then become immediately applicable. When user
management (see page 63) is active, the imported default values are
only applicable for the user currently logged on.
Service menu which can only be accessed by a service technician.

The administration menu (see page 61) enables a user with the appropriate
permissions to access extended system functions.

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Operating the Teleflex VX

Menu
Description
item
This submenu enables various settings to be made for scale graduation on
the X-axis and for entering the propagation velocity. It provides the following
menu items:
Depending on the setting of this switch, the X-axis is either scaled in
seconds (runtime) or in length units (distance).
Only available when the X-axis is scaled in length units (see above)
This menu item can be used to switch the unit of the X-axis between
meters and feet.
Only available when the X-axis is scaled in length units (see above)
To achieve reliable distance details, knowledge about the exact signal
propagation velocity for the test object is absolutely essential. This
can be specified in two different ways:
• NVP (Nominal Velocity of Propagation) - The signal propagation
velocity is stated relative to the speed of light,
e.g. NVP 0.53 = 0.53 x c.
• SPEED - The signal propagation velocity is stated with half the
actual propagation speed (the cable's so-called V/2).

Depending on the above settings, a default propagation velocity value

can be defined using the menu items and NVP respectively. This
value is then preset whenever a measurement is started.
Submenu for displaying and exporting important system information.
Information on software version

Information on system hardware and the current IP address

This menu item enables messages stored in the system log to be

displayed).
This menu item enables the system log to be exported to an inserted
USB flash drive (SystemLog-directory).
Option for checking key assignment for a connected USB keyboard.

This menu item can be used to define whether the system information are to
be printed through a connected printer or saved as a PDF file (into the
PdfFiles directory of an inserted flash drive).

To enable system information to be printed out directly, the type of

printer connected must be configured beforehand (see page 59).

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 Operating the Teleflex VX

5.6.1 Data menu -

The Data menu enables stored measurement data to be imported, exported or deleted. It
contains the following menu items:
Menu
Description
item
DEL Menu item to enable measurement data records to be deleted from the
History database. The measurements to be deleted must be marked
beforehand (see page 54).
Menu item that enables measurement data records from the History database
to be exported to the inserted USB flash drive (Winkis directory).
The data records to be exported must be marked beforehand (see page 54).
Menu item to enable measurement data records / logs to be imported. To do
so, a window is opened in which the user can navigate through the directories
on the plugged-in USB flash drive.
List of common cable types that can be extended by own cable and insulation
types. This eliminates the need to manually enter the propagation speed
during cable fault pre-location. Instead, the appropriate cable type can simply
be selected from the list and its stored propagation speed automatically
applied.
Two filters (cable type and cable insulation) can be used to limit the number
of cables displayed.
Saved cable types can only be edited or deleted with administration rights
(see page 61).
Menu item to enable the cable list (see above) to be exported to a USB flash
drive (Cables directory).

58
Operating the Teleflex VX

5.6.2 Basic settings -

The following menu items can be used to adapt the software's basic settings:
Menu
Description
item
Sets the language.
Select the desired language by turning the rotary encoder and activate by
pressing it. The language selection is immediately active.
This submenu enables the following screen settings to be made:
This menu item enables the user to select one of the available screen
layouts.
This menu item can be used to change the line thickness for the
traces to meet one's own requirements.
For systems with a touch sensitive display, this menu item can be
used to enable / disable touch functionality.
Menu item to show/hide the mouse cursor. In order to operate the
software via a connected mouse, the mouse cursor must be enabled.
Menu item to enable / disable the on-screen keyboard.
Date and time.

This menu item enables a connected printer to be selected from a variety of

supported printers.

Before buying a new printer, please contact your Megger sales

partner for a list of supported printers.

59
 Operating the Teleflex VX

Menu
Description
item
This menu item enables the following functions that influence the
measurement sequence to be activated or deactivated:
If this option is activated, all three phases are automatically
selected upon entering the operating mode.
If this option is activated, all three phases are automatically
selected upon entering a TDR operating mode (this only applies
for TDR measurements via the LV cable).
If this option is activated, all three phases are automatically
selected upon entering the operating mode.
If this option is activated, the phase selection is always reset upon
exiting the operating mode and must be conducted again upon
each return.
If this option is activated, the selected voltage range is always
reset upon exiting / changing the operating mode.
If this option is activated, multiple phases can be selected in
operating mode.
Activates / deactivates automatic scaling adjustment of the X axis
as soon as a trace is recorded.
Activates / deactivates automatic gain adjustment of the Y axis as
soon as a trace is recorded.
Activates / deactivates the automatic positioning of the marker on
the suspected fault location as soon as a trace is recorded.
Layout of the connected keyboard.
This menu item enables the currently logged-on system user to be changed.
Once a new user has been selected, the new user's default settings are then
loaded. The menu item is only available if at least one user exists in the
database. The administrator can manage user accounts in the administration
menu (see page 61).
Menu item for switching the voltage input / voltage display. Voltages are given
as peak values or effective values depending on the setting.
However, the menu item is only available if the system is equipped with a
Test and Diagnosis Module (TDM).

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Operating the Teleflex VX

5.6.3 Administration menu - (administration password required)

Purpose The administration menu is password-protected and provides access to advanced system
settings such as the user administration, as well as update and backup functions.

The software's menu structure has concealed menu items added to it when administration
rights are issued. These enabled functions, which are only rarely used during day-to-day
operation of the device, are described in greater detail throughout the course of the
manual.

Access To open the administration menu, you must first enter the password. Proceed as follows:
Step Action
1 Select menu item , to access the Control Panel and then select menu
item .
2 Select menu item , to enter the password.
Result: The password entry dialogue appears in the display.
3 Enter the password and confirm your entry with OK.
Result: If you entered the password correctly, the menu items of the
administration menu appear (see below).
If your entry is incorrect, you must repeat the procedure from Step 2.

Menu items The administration menu contains the following menu items:
Menu
Description
item

| These menu items can be used to back up or update (see page 62) the
individual modules of the software.
This menu item can be used to completely empty the database, i.e. all
measurement results, users, cable types and system logs are deleted.
However, calibration and configuration data is retained.
After you select this function, the system is restarted. After the restart, you
must once again confirm that you want to reset the database.
Before resetting the database you should always make a backup (see
page 62).
Menu item used to manage the users accounts (see page 63) of the
system.
This menu item can be used to enable operating modes and functions in
the software that have not yet been activated.
An appropriate unlock key is required for the enabling process. Please
contact your local Megger sales partner for more information on activating
a function or an operating mode.
Menu item to activate/deactivate the connection lead calibration mode (see
page 64).
Menu item used to disable administrator rights and to protect the
administration menu with a password again.

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 Operating the Teleflex VX

5.6.3.1 Backing up and updating data - |

Data backup Menu item can be used to back up all the files required to recover the system.

Depending on the type of system, the following files are exported to the inserted USB
flash drive directory Backup_<serial number> during a backup:
File Explanation
application_<version>.img The application file itself
printforms.tar All print templates, log templates and logos
Languages*.tar Language file that contains all the available menu
languages in the system.
SebaKMT.cfg.xml Configuration file
backupDB.sql A backup of the database, containing the saved
measurement data, cable database, user database and
the default values.
*.txt Log files of the system and the included test attachments.

Because the backupDB.sql file contains the complete database and therefore can only be
loaded again in its entirety, the following data can also be exported separately using the
menus so that they can be transferred separately (e.g. to another system):
• Measurement data (see page 58)
• User account data (see page 63)
• Default values (see page 56)
• Cable data (see page 58)

Loading software Menu item can be used to install the individual software modules (see above) into the
modules system. This way, you can restore or update modules, or transfer them to another system.

When you open the function, a file browser appears to help you navigate through the files
on the plugged-in USB flash drive. Only the files which the system identifies as software
modules and which the user is authorised to load are displayed.

This means that the application itself, the database and the configuration file can only be
loaded by users with enhanced administrator rights. If you do not yet have the appropriate
rights, please contact your local Megger sales partner.

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Operating the Teleflex VX

5.6.3.2 User administration -

User administration allows you to set up various user accounts on the system, so that
each user can adjust the default values and the way the system behaves according to his
own preferences.
Menu
Description
item
A new user can only be created if a user name is entered. You can also limit
the maximum voltage that the user can adjust and protect the account with a
password.
If you do not specify a password, the user does not need to enter a password
when logging in, which makes the procedure quicker.
The default values for the new user are the same as the factory settings. If
necessary, you can import (see page 56) the default values from another user
account (or even another system).
This menu item can be used to edit the name, voltage range and password of
a user.
This menu item can be used to delete individual users from the user
database. If the last user has been deleted, the user management is
deactivated and there is no longer a login procedure when the system is
started.

You can only delete the last user by interrupting the login.
When deleting a user, his default values are lost. Therefore –
particularly for the last user – you should export the default values
beforehand (see page 56) beforehand.

This menu item allows you to export a selection of user profiles from the
system together with the respective standard values as an XML file to the
inserted USB flash drive’s User directory.
This menu item can be used to import user profiles that are stored on an
inserted USB flash drive into the system.
This does not affect existing users. If two user names are the same, the
system asks whether you want to overwrite or keep the existing user in the
system.

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 Operating the Teleflex VX

5.6.3.3 Connection Lead Calibration -

Necessity A properly calibrated connection lead (HV connection cable and LV connection cable)
ensures the accuracy of all operating modes which function according to the TDR principle
(Teleflex, IFL and all ARM modes). The length of the connection lead is not only
automatically hidden from the visible diagram area, but also automatically subtracted from
the calculated distance specifications.

As a principle, a calibration was already performed using the connection cables supplied
during the final test. A repeat calibration should only be performed when one of the
connection cables was replaced with a cable with a different length. In this case, an
individual calibration must be performed for all respective operating modes and phases
with a signal path which is affected by the cable replacement.

Procedure To calibrate a pre-measuring cable, proceed as follows:

Schritt Aktion
1 Activate calibration mode using the menu item in the administration menu.
2 Start the operating mode for which you wish to perform the calibration.
3 Select the phase for which you wish to perform the calibration.
4 Perform a measurement with the end of the connection cable open.
5 Exit the operating mode and then open it again immediately. Select the same
phase as in Step 3.
6 Open the trace recorded in the history database beforehand (see page 52).
7 Short circuit the connection cable at its end, and perform another
measurement.
8 Select the menu item and move the red cursor exactly to the point at which
both traces diverge. Then press the rotary encoder and keep pressing it until
the new zero position is applied.
9 Repeat the procedure, if necessary, for other phases and operating modes.
10 Deactivate calibration mode using the menu item in the administration
menu.

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 Conducting measurements

6 Conducting measurements

6.1 Good to know …

6.1.1 Propagation velocity

Introduction To enable the exact distance between the start of the cable and the fault position to be
calculated, the TDR must be aware of the propagation velocity in the cable. This velocity
depends on several physical variables in the cable: insulation material and thickness,
cable diameter, etc.

If the setting for the propagation velocity value is out by 2%, then the measurement result
will also be out by 2%.

Determining unknown If the correct physical length of the cable under test is known, the propagation velocity
propagation velocity can be measured. To do so, perform a pulse reflection measurement, and make sure that
the end cursor is positioned exactly on the identified end of the cable. The propagation
velocity is then continuously altered until the actual cable length is displayed. The
propagation velocity should then be noted down for future measurements.

If the length of the cable under test is unknown because of elbows, reserves, etc., then a
piece of the same cable can be measured in the workshop and the determined
propagation velocity used for the cable out in the field. A reference cable such as this
however, should be at least 50 metres in length.

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 Conducting measurements

6.1.2 Pulse width

Due the attenuation and dispersion characteristics of a cable, signals get changed in
amplitude and shape as runtime progresses. Naturally, this also applies to the measuring
pulse and its reflections.
Narrow pulses, which contain a large portion of high frequencies, are subject to greater
deformation than wide pulses. Consequently, narrow pulses are more suited for shorter
ranges in which they can provide an image with higher resolution than wide pulses,
whereas over larger distances they suffer from greater attenuation and dispersion. Here,
wide pulses (up to 10 μs) must be used, as they are subject to significantly lower
attenuation and therefore they supply a much clearer echo over longer distances.

The following table provides an overview of the pulse widths recommended for each
required distance range:
Required distance range Recommended pulse width
<100 m 20 ns
100 m … 200 m 100 ns
200 m … 1 km 200 ns
1 km … 2.5 km 500 ns
2.5 km … 10 km 1 µs
10 km … 30 km 2 µs
30 km … 80 km 5 µs
>80 km 10 µs

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Conducting measurements

6.1.3 Typical TDR reflectograms

The following illustration shows several idealised examples for TDR reflectograms:

Open end, faultless

cable

Parallel resistance

Short-circuit

Series resistance

Break

Change of cable type

Z1 > Z2 (change to lower
impedance)

Change of cable type

Z1 < Z2 (change to higher
impedance)

Joint / transformer

T-joint

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 Conducting measurements

6.2 Standard functions

Generally available The following standard functions are available in the respective measurement menu on
functions the Teleflex VX in all operating modes in which measurement data are recorded and
displayed :
Menu
Description
item
This menu item can be used to move the cursor along the X axis. The
current, voltage, time or distance values of the currently marked position
are displayed in the bottom part of the screen.
This menu item can be used to increase or reduce the visual range on the
X-axis. The section aligns itself with the current cursor position here.

M This menu item can be used to access a list of all data records stored in
the History database which match the currently active operating mode.
Only the permanently stored data records are taken into account here.
Using the rotary encoder enables a data record in the list to be selected
and then accessed.
This way, e.g. a reference trace previously recorded on the same cable can
be quickly located and compared with the current trace.
Furthermore, the menu item can be used to store the current
measurement permanently in the History database.

Standard functions for Due to the numerous functions, the measurement menus of all operating modes working
pulse reflection according to the TDR principle (e.g. Teleflex operating modes, ARM operating modes,
measurements ICE and DECAY) feature two additional submenus.

In the actual measurement menu and in the Teleflex menu , all measurement
parameters relevant for recording and displaying the curves as well as several additional
functions are consolidated. Depending on the operating mode, these menus include a
selection of the following menu items:
Menu item Description
In all the operating modes in which the measurement has to be triggered
(e.g. ARM), the respective trigger threshold can be manually adapted.
Normally the trigger threshold is automatically pre-configured to a suitable
value. If the measurement should however be interrupted by low voltage
reflections which are clearly not induced by the transmitted pulses, then
the trigger threshold should be manually increased. If, instead of this, no
reflections are displayed at all, then it may be helpful to reduce the
threshold.
This menu item can be used to set the gain.
For pulse reflection and ARM measurements, the gain can be set for the
received signal. If the setting is good, the reflection for the open cable end
can be clearly identified as a positive reflection.
In the ICE and Decay operating modes, any change of the gain setting
requires a new fault flash-over to be triggered for the effect to become
visible.

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Conducting measurements

Menu item Description

This menu item can be used to set the measurement range (X-axis).
For pulse reflection and ARM measurements, the end of the cable should
be visible as a positive reflection at the right-hand edge of the screen.
In the ICE and Decay operating modes, the measurement range should
be set to five times - ten times the cable length.
Whenever the measurement range is changed, the settings for filter, pulse
width, pulse amplitude and de-attenuation are automatically adapted.
This menu item can be used to move the red cursor along the X-axis.
By pressing and holding the rotary encoder a blue mark can be set on the
current position of the cursor whereupon the red cursor can then be
moved further. In this way, e.g. the real distance between two noticeable
positions along the trace can be measured. Depending on the operating
mode, the distance (calculated from the runtime) between the two marks
is shown in one of the following fields at the lower edge of the screen:
The full distance between the blue mark and the red cursor

Half the distance between the blue mark and the red cursor (in
Decay operating mode only).
This menu item can be used to set the bandpass filter, which limits the
frequency range to be measured. Interference signals outside this
frequency range are suppressed.
The filter value is reset to its default value as soon as one of the following
operations has been performed:
• change to the operating mode
• change to the pulse width
• change to the measurement range

| NVP Setting signal propagation velocity (see page 65).

The type of entry depends on the system settings (see page 56).
The signal propagation velocity can also be adopted directly from one of
the cables filed in the Cable database (see page 58). To do so, the menu
item must first be called up and then the rotary encoder pressed for at
least two seconds.
This menu item can be used to delete individually no longer required
traces from the current display, to make it easier to read the important
traces.
The de-attenuation function enables the attenuation of the electrical
pulses in the cable to be counteracted. This is done through amplification
of the input signal which increases as the runtime increases, i.e. as
distance increases the reflections are further amplified. The amplification
increases exponentially up to a fixed maximum amplification.
The ideal de-attenuation setting depends on the length of the cable, so
the de-attenuation setting is effectively adapted whenever the measuring
range is changed.
This menu item can be used for all types of pulse reflection measurement
to set the pulse width (see page 66) for the measurement pulse.

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 Conducting measurements

Menu item Description

This menu item can be used to manually set the pulse amplitude if
required. For fault positions in close range, it may be helpful to experiment
with lower pulse amplitudes. Conversely, higher amplitudes are suited for
particularly long cables.
With each adaptation of the distance range (X-axis) the pulse amplitude is
automatically adjusted by the system to a suitable value.

The trace functions menu which can be activated during a pulse reflection measurement
using the menu item provides diverse options to adapt the arrangement of traces on
the screen to meet individual requirements:
Menu
Description
item
This menu item can be used to move trace 1 along the Y-axis.
This menu item can be used to move trace 2 along the Y-axis.
This menu item can be used to move trace 3 along the Y-axis.

This menu item can be used to move all visible traces along the Y-axis.

| This menu item can be used to move the traces mapped on the display
further apart from each other along the Y-axis and back in position.
All traces are separated from each other by 50 pixels along the Y-
axis.
The traces are moved back into their original position and they are at
the same level again.
This menu item can be used to move all visible traces along the X-axis.

The difference between trace 1 and 2 is used to calculate and display a new
trace. All other traces are hidden here.
The difference between trace 2 and 3 is used to calculate and display a new
trace. All other traces are hidden here.
The difference between trace 3 and 1 is used to calculate and display a new
trace. All other traces are hidden here.
This menu item can be used to move one of two traces along the X-axis.

Functions which can only be applied to traces 1 to 3 are only available when the
respective slots are actually occupied.
Loading a trace from the History database into one of these slots has to be
done by calling up the individual trace (see page 54) instead of the complete
measurement data record.

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Conducting measurements

6.3 Systematics of cable fault location

Introduction Daily work with a cable test van is divided into the following two main areas:
• Condition-oriented maintenance
Testing, diagnosis and partial discharge measurement
• Event-oriented maintenance
Localisation of all types of cable faults

While there are many different concepts of and approaches to condition-based

maintenance, the approach described below has established itself in event-oriented cable
fault location.

Schema The following schema illustrates the typical approach for detection, classification and
location of cable faults using the methods of measurement available:

Insulation test
to determine the affected
Fault classification

conductors and for fault

classification with the ISO module
Low resistive fault High resistive fault
or an external device (page
(<10 kΩ) (>10 kΩ)
72Fehler! Textmarke nicht

Determination of the breakdown voltage

by charging with DC test voltage (page 78)

Fault prelocation with suitable HV prelocation methods

Pulse reflection method (TDR)
such as:
(page 87)
Fault prelocation

• Arc reflection method (ARM) (page 90),

• Voltage decoupling (DECAY) (page 96),
• Current decoupling (ICE) (page 110)

For difficult faults

Burning for conversion of the fault

resistance (page 108)
pinpointing

Precise determination of the fault position through surge

Fault

pinpointing (page 110) or audio frequency

measurement (page 114)

71
 Conducting measurements

6.4 Insulation measurement

Requirements In order to perform an insulation test, the test van must be equipped with either the internal
ISO module (measuring via the Teleflex VX) or an external insulation resistance tester
(e.g. Megger). The external insulation resistance tester used may not have an output
voltage exceeding 1 kV and with suitable measuring lines can either be connected to the
external sockets of the control panel or the external sockets in the top tray (not
available in combination with the internal ISO module).

Purpose The first step in locating a cable fault – fault classification – should always include an
insulation and resistance measurement. The measured values shed light on the
characteristics of the fault and thereby narrow down the eligible prelocation methods and
conductors to be examined.

6.4.1 Insulation testing with an external insulation tester

Procedure Proceed as follows to carry out a measurement:

Step Action
1 Connect a suitable insulation resistance tester to the external sockets in the
drawer or at the control panel.
2 On the Teleflex VX, select the appropriate operating mode:
Insulation testing with an insulation resistance tester connected
EXT
to one of the sockets in the drawer
 Insulation testing with an insulation resistance tester connected
to one of the sockets of the control panel
3 In the phase selection menu, select the phases whose insulation resistance
you want to measure and close the menu using .
4 Start the operating mode using the menu item .
5 Geben Sie die Hochspannung über den „HV ON“-Taster frei.
6 Carry out the insulation resistance measurement with the insulation tester.

For information on operating the insulation resistance tester used,

refer to the corresponding operating manual.

7 If necessary, change the phase selection on the Teleflex VX and perform

further measurements.

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 Conducting measurements

6.4.2 Insulation testing with internal ISO module

Selecting the operating The operating mode can be accessed directly from the main menu using the menu item
mode and phases .

Directly upon entering the operating mode, the phases to be tested are queried. The
phases must then be configured according to the actual connection situation.

It is also possible to activate multiple options. The measurement then takes place
sequentially. If one of the “phase-to-phase” options (for example L1-L2) is selected, a
floating measurement is taken between the two phases.

The phase selection menu must then be closed using . If necessary, the phase
selection can be opened later and modified.

6.4.3 Measurement of insulation resistance and test object

capacitance

Introduction Based on a measurement of the ohmic insulation resistance, a basic error classification
can often be made in advance.

Thus, low- and medium-resistance cable faults can, for example, be directly detected and
appropriate follow-up measurements (e.g. Teleflex measurements) can be undertaken.

The deviations in resistance within a cable system can also be used in the case of high-
resistance cable faults to draw conclusions about the affected phases.

It can also be helpful to repeat resistance measurements after application of certain pre-
location methods (e.g. ARM, ICE) or fault conversion methods (burning) and to compare
the measurement results with those stored in the database.

With the integrated ISO module, the complete measuring range from 1 Ω to 2 GΩ can,
thanks to the selectable test voltages, be measured with high resolution.

The integrated resistance-dependent automatic switching of the test voltage can also be
deactivated as needs require.

Test voltage Measurement range

500 V / 1000 V Insulation resistance: 1 kΩ … 2 GΩ
Cable capacitance: 0.1 μF … 19.9 μF
Low voltage (<6 V) Insulation resistance: 1 Ω … 1 kΩ

73
 Conducting measurements

Setting the In preparation of the actual measurement, the following parameters can be set:
measurement
parameters Menu item Description
This menu item can be used to switch between automatic and manual
mode.
In automatic mode, the resistance and capacitance values are always
measured. A selection must only be made between the upper test
voltages of 500 V and 1000 V. The system automatically switches to low
voltage when determining a low-ohm resistance, since the resistance
values in this measuring range can only be measured with low voltage.
In manual mode, you may only determine either the resistance or the
capacitance during a test. The three test voltages of 500 V, 1000 V and
low voltage (<6 V) are available for selection. No automatic switching
between the voltages occurs during the measurement.
This menu option is used to set a test voltage of 1000 V.

This menu option is used to set a test voltage of 500 V.

Only available in manual mode

This menu option is used to set a low test voltage (<6 V).
Only available in manual mode
Switching between resistance and capacitance measurement.

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Conducting measurements

Measurement After the measurement parameters have been set as described above, the measurement
procedure can be started via the menu item .

Depending on the set mode, the system measures the resistance and/or capacitance
values for each selected phase combination.

The results are shown in a table:

The measured parameter, date and time of measurement as well as the test voltage used
can be read from the table header for each measurement (column).

A new column is created for every measurement begun. The columns start on the left with
the most current measured values and end on the right with the oldest measured values.
A maximum of six columns can be adjacently shown. For each additional measurement,
the column with the oldest measurement results is deleted.

The user can also manually delete the column with the respectively oldest measurement
results via the menu item .

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 Conducting measurements

6.4.4 Time-dependent measurement of resistance -

Introduction Through a time-dependent measurement of resistance, the chronological change of the

absorption characteristics of the insulating material and thus the degree of moisture and
dirt in an insulation can be tested.

A continual rise of the recorded resistance indicates an intact insulation. A flat or

downward sloping curve can indicate a dirty, moist or damaged insulation, for example.

To obtain comparable measurement results, the chronological progress can be used to

calculate the well-known coefficients PI (Polarisation Index) and DAR (Dielectric
Absorption Ratio).

For the DAR coefficient, the value measured after one minute is divided by the measured
value after 30 seconds. This coefficient should therefore be used primarily for evaluation
of newer insulating materials, which exhibit a faster decline of dielectric absorption
currents.

For other insulation materials, with absorption characteristics that normalise more slowly,
the PI coefficients should be determined. For these, the value measured after 10 minutes
is divided by the measured value after one minute.

Opening the operating The time-dependent measurement of resistance is integrated into the insulation test
mode and selecting the operating mode and can be accessed using the submenu item .
phases
Directly upon entering the operating mode, the phases to be tested are queried. The
phases must then be configured according to the actual connection situation.

The phase selection menu must then be closed using . If necessary, the phase
selection can be opened later and modified.

Setting the In preparation of the actual measurement, the following parameters can be set:
measurement
parameters Menu item Description
Activates/deactivates the function for determining the DAR coefficients.

Activates/deactivates the function for determining the PI coefficients.

This menu option is used to set a test voltage of 1000 V (if possible, this
voltage value should be set for the time-dependent measurement of
resistance).
This menu option is used to set a test voltage of 500 V.

This menu option is used to specify a maximum test time of up to

15 minutes.
The minimum test time is automatically set to 1 minute (when
determining the DAR coefficients) or 10 minutes (when determining the
PI coefficients).

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Conducting measurements

Measurement After the measurement parameters have been set as described above, the measurement
procedure can be started via the menu item .

The determined resistance values are shown on the screen during the course of the
measurement as a curve over time.

With the completion of the measurement, any DAR and/or PI coefficients that are
determined are shown in a dialog box.

Evaluation of the test The course of the curve itself as well as the determined coefficients can provide
results information on the state of the insulation.

Example resistance curve of an intact

insulation (DAR value about 1.5)

Example resistance curve of a defective insulation

(humidity, dirt, DAR value < 1.2)

The following table provides generally accepted guidelines values that can be used to
evaluate the measurement:
PI value DAR value Condition of insulation
<1 <1 poor
1 to 2 1 to 1.3 questionable
2 to 4 1.3 to 1.6 Good
>4 >1.6 excellent

A comparison with intact cables of identical construction or with previous measurements

should also be taken into account.
To do so, previous measurements from “History” database (see page 52) can be
accessed and the resistance curves compared. By selecting the menu option , the
determined DAR and/or PI coefficients can also be displayed for comparison.

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6.5 Cable testing -

Selecting the operating The operating modes for cable testing are usually grouped not directly in the main menu
mode but rather in the sub-menu .
Menu item Operating mode
Cable testing with VLF cosine rectangular voltage using the optional VLF
CR-54 kV or VLF CR-70 kV test attachment.
Cable testing with negative DC voltage (using the internal voltage
source)
Cable test with positive or negative DC voltage using the optional test
and diagnosis module (TDM)
Cable testing with VLF cosine rectangular voltage using the optional test
and diagnosis module (TDM)
Cable testing with VLF sine wave voltage using the optional test and
diagnosis module (TDM)

Setting the The phases and the voltage range are automatically queried when entering the operating
measurement mode, however − like all other settings − they can be adjusted until the actual start of the
parameters test.

Depending how the test van is equipped and the selected operating mode, the following
measurement parameters can be set:
Button /
Description
Menu item
The phase selection must be carried out in accordance with the actual
type of connection.
It is also possible to test several phases at once to save time. To this
end, the phase selection menu permits the selection of more than one
option.
The phase selection menu must then be closed using .
The test duration is shown in minutes. On expiry of the test duration, the
high voltage is switched off automatically.
Voltage range for the upcoming test. After starting the test, the actual test
voltage can only be set within this range.
Only adjustable for tests with sine wave or square wave voltage
This menu item is used to change the frequency of the VLF test voltage
(0.01 Hz to 0.1 Hz). The HD 620 S1 and HD 621 S1 harmonisation
documents recommend the 0.1-Hz frequency for VLF tests.
As the maximum permitted test frequency depends on the determined
cable capacitance and the test voltage being applied, it may be
necessary to adjust the test frequency set and about which the user was
informed at the start of the test.
Only adjustable for VLF tests with sine wave or square wave voltage
Switch between sine wave and square wave mode.
Can only be set for DC voltage testing with a bipolar test voltage source
This menu item is used to specify the polarity of the DC test voltage.

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 Conducting measurements

Button /
Description
Menu item
Can only be set for testing with the internal test voltage source
Setting of the slew rate in kV/s. After confirmation of the test voltage, the
test object is charged continually at the set slew rate until it reaches the
set value. The voltage increase can be paused and resumed.
In the Manual setting, the increase of the test voltage is regulated
manually with the rotary control and the test object is charged to the set
value as quickly as possible without requiring confirmation. The test
voltage then remains at this level until the set value is again manually
increased or decreased.
Can only be set for testing with the internal test voltage source
Limitation of maximum current (0.1 mA … 300 mA)
The test voltage source automatically suspends the test if this value is
exceeded. A message shows the cause of tripping and the maximum
attained voltage.
Can only be set for testing with the internal test voltage source
Current monitoring during charging phase on/off
This menu item can be used to determine whether the test is
automatically stopped, if the specified maximum current is exceeded
during the charging phase. If this option is disabled, the maximum
current is monitored during the plateau phase only. In order to ensure
fast switch-off and avoid unnecessary stress to the device under test, it is
recommended to enable this option for tests with test voltages <10 kV.
Only adjustable for VLF tests with sine wave or cosine rectangular
voltage
This menu item can be used to perform a partial discharge measurement
in parallel with the standardised testing. A prerequisite for this is that the
test van has a suitable partial discharge diagnostic system.
Once the option has been activated, any further operator actions must be
performed using the “PD Detector” software.

Detailed information on the operation of the “PD Detector”

software can be found in the operating manual for the partial
discharge measurement system.

Notes on selecting the The requirements for a meaningful cable test are found in the harmonisation documents
test voltage and test HD 620 S1:1996 and HD 621 S1:1996 and often in company-internal testing guidelines
time as well.

The following table provides a selection of proven test parameters for various applications:
Application Test voltage Test duration in
minutes
VLF test (initial use) 3Uo 15 to 60
VLF test (on aged cables) 1.7 … 3Uo 60
DC test (on PILC cables) 4 … 8Uo 15 … 30

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 Conducting measurements

Starting the test Once all the relevant parameters for the test as well as the phase(s) have been set, the
test can be started using the menu item. Following this the high voltage must be
authorised using the “HV ON” button and the test voltage set.

As soon as high voltage is enabled, the “HV OFF” button lights up red signalling “high
voltage at the HV output”.

The dialogue for setting the voltage closes automatically after a few seconds for safety
reasons but it can be accessed again using the U menu item.

Depending on the operating mode and type of test voltage source, a load detection is
carried out at the beginning of the test. If the load characteristics (capacitance and
insulation resistance) do not permit a test with the set parameters, this is indicated on the
screen by a system message.

For tests with sine wave or rectangular voltage, testing using a lower frequency is offered
where required. The user can then either cancel the test or start it using a different
frequency. Tests with DC or cosine rectangular voltage must be stopped in any case and,
if possible, restarted using a lower test voltage.

Performing the test The voltage curve can be followed on the screen during the test. In DC, square wave and
cosine rectangular mode leakage current measurement is carried out too.

In the case of tests with DC, square wave or cosine rectangular voltage you can switch to
expert view and display the periodic onset of charge current using the menu item (only
available for tests using the optional test and diagnosis module (TDM)).

The test duration can be adjusted retrospectively even while the test is ongoing using the
menu item or reset using the menu item.

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Conducting measurements

Alongside the current and voltage values, some other relevant parameters and
measurement values are shown at the bottom edge of the screen depending on the
operating mode and the type of test voltage source.
Symbol Description

Remaining test duration

Set test duration

Actual test frequency

The load capacitance determined at the start of the test

The insulation resistance determined at the start of the test

Finishing the test If a test time was defined, the high voltage is automatically switched off at the end of this
time. The measurement can be manually deactivated at any time via the “HV OFF” button
or the menu item.

If a voltage breakdown occurs in the test object during the test duration, the test is also
interrupted. In which event, the test does not qualify as having been passed. The user is
informed about the breakdown voltage and – for multi-phase testing – the affected phase.

Irrespective of whether the high voltage is switched off automatically or manually, the HV
output is discharged and earthed. The test data logged up to the switch-off are recorded
in the history database (see page 52).

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 Conducting measurements

6.6 Sheath test and sheath fault pinpointing (optional)

Prerequisites The test van must be equipped with a test and diagnosis module (TDM).

Introduction The test for sheath fault can be performed with a negative DC voltage of up to 20 kV,
which makes it possible to also test cables with thicker outer sheaths (for example, cables
with a rated voltage of 230 kV).

If a voltage breakdown occurs during the course of a sheath test or the measured leakage
current indicates that there is a sheath fault, pinpointing the sheath fault can be started
immediately after the test.

During sheath fault pinpointing, DC pulses with an adjustable pulse rate are coupled with
the shield affected by the earth fault.

With each coupled pulse, the current flowing into the ground forms a voltage gradient
around the point of escape (the fault location in the sheath), the centre of which can be
located precisely with the assistance of a earth leakage detector and its earth rods (step
voltage method).

Selecting the operating At the start of sheath testing, the submenu of the test operating modes must be opened
mode using the menu item and from this, the menu item must be called up.

Sheath fault pinpointing can be started directly from the main menu or from the submenu
using the menu item .

If the test van is equipped with a dedicated device for sheath testing and sheath fault
location (for example, MFM 10) the measurements are instead performed directly on this
device (see page 136).

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6.6.1 Testing a cable sheath -

Setting the test The phases and the voltage range are automatically queried when entering the operating
parameters mode, however − like all other settings − they can be adjusted until the actual start of the
test.

The following test parameters can be set:

Button /
Description
Menu item
The phase selection must be carried out in accordance with the actual
type of connection.
It is also possible to test several sheaths at once to save time. To this
end, the phase selection menu permits the selection of more than one
option.
The phase selection menu must then be closed using .
The set voltage range limits the maximum voltage that can be set during
the test.
In terms of the relevant standards (such as the VDE 0276), which may
however differ from the local regulations or standards, the following
guidelines are specified:
• PVC cable ≤3 kV
• PE medium voltage cable ≤5 kV
• PE high voltage cable ≤10 kV
The duration of the test can be specified within a range of 1 to 90
minutes. In the relevant standards (e.g. VDE 0276), the test duration of a
sheath test is specified as being between 5 to 10 minutes depending on
the cable type.
Setting of the slew rate in kV/s. After confirmation of the test voltage, the
test object is charged continually at the set slew rate until it reaches the
set value. The voltage increase can be paused and resumed.
In the Manual setting, the increase of the test voltage is regulated
manually with the rotary control and the test object is charged to the set
value as quickly as possible without requiring confirmation. The test
voltage then remains at this level until the set value is again manually
increased or decreased.

Starting the test Once all the settings have been made, the test can be started with the menu item.
Following this the high voltage must be authorised using the “HV ON” button and the test
voltage set.

As soon as high voltage is enabled, the “HV OFF” button lights up red signalling “high
voltage at the HV output”. The test system starts with voltage conditioning. The voltage
can be also adjusted during the further course of the test by means of the menu item .

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 Conducting measurements

Performing the test During the test the voltage curve and the measured leakage current are shown in the
display area. The test duration can be adjusted retrospectively even while the test is
ongoing using the menu item or reset using the menu item.

Alongside the current and voltage values, some other relevant parameters and
measurement values are shown at the bottom edge of the screen:
Symbol Description

Remaining test duration

Set test duration

Finishing the test If a test time was defined, the high voltage is automatically switched off at the end of this
time. The measurement can be manually deactivated at any time via the “HV OFF” button
or the menu item.

Irrespective of whether the high voltage is switched off automatically or manually, the high
voltage output is earthed and the test object is discharged by means of an internal
discharge-resistor. The test data logged up to the switch-off are recorded in the history
database (see page 52).

Evaluation of the test If the leakage current values that occur during testing are above the limit values defined
results by the cable owner, the tested cable should be examined in more detail soon or at
minimum a shorter testing cycle should be introduced.

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6.6.2 Pinpointing a sheath fault -

Setting the The phases and the voltage range are automatically queried when entering the operating
measurement mode, however − like all other settings − they can be adjusted until the actual start of the
parameters pinpointing.

The following measurement parameters can be set:

Button /
Description
Menu item
The phase selection must be carried out in accordance with the actual
type of connection.
The phase selection menu must then be closed using .
The set voltage range limits the maximum voltage that can be set during
the pinpointing.
In terms of the relevant standards (such as the VDE 0276), which may
however differ from the local regulations or standards, the following
guidelines are specified:
• PVC cable ≤3 kV
• PE medium voltage cable ≤5 kV
• PE high voltage cable ≤10 kV
This menu item can be used to set the pulse rate of the direct current
pulse in seconds.
Example: For a pulse rate of 1:3, each direct current pulse with a duration
of 1 second is followed by a pause of 3 seconds.

0 kV

1s 3s

This menu item can be used to enable/disable a pause of one pulse

between two cycle sequences. For the example shown above, this would
mean that an impulse is omitted after the first three direct current pulses.

By means of this "dropout", the signal can be more clearly identified in

areas with many interfering signals (e.g., stray currents caused by electric
rail vehicles).
This menu item can be used to enable / disable the voltage pulsing. If
disabled, the cable shield is simply charged with constant DC voltage.

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 Conducting measurements

Starting the pinpointing Once all the settings have been made, the pinpointing can be started with the menu
item. Following this the high voltage must be authorised using the “HV ON” button and
the test voltage set.

As soon as high voltage is enabled, the “HV OFF” button lights up red signalling “high
voltage at the HV output”. The test system starts with voltage conditioning. The voltage
can be also adjusted during the further course of the pinpointing by means of the menu
item .

Pinpointing sheath After high voltage has been enabled and the desired voltage has been set, the fault
faults position can be accurately pinpointed with the assistance of an earth fault locator (e.g.
ESG NT).

For more details about operating the earth fault locator, please read the
accompanying instructions.

The safety of the test van that is in operation must be guaranteed at all
times by the persons responsible for the test van in accordance with the
applicable safety regulations and guidelines, also during line and fault
WARNING location!

Completing the After the fault location has been completed, the high voltage must be switched off
measurement manually using the “HV OFF” button or the menu item . The high voltage output is then
earthed and the test object is discharged by means of an internal discharge-resistor.

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6.7 Pulse reflection measurement (TDR) -

Introduction Low-resistance cable faults can be localised using the tried-and-tested and widely-used
pulse reflection measurements. This method is based on the radar principle and makes
use of the fact that any sudden deviations in the characteristic impedance of a cable reflect
part of the energy transmitted into the cable. The degree of reflection is dependent on the
magnitude of the deviation in the characteristic impedance, the number of reflections, the
cable length and the distance to the fault position.

The recorded curve shows any deviation in the cable’s characteristic impedance.
Naturally, this means that not only fault positions, but also other changes in resistance
such as, e.g. in joints are also recorded. These recordings can indeed also represent an
additional orientation aid for accurate pinpointing of the fault position.

The special IFL operating mode (Intermittent Fault Locating) can be used to localise
sporadically (time-variant) occurring low-resistance cable faults (caused, e.g. through
traffic vibrations).

To this end, the individual curves in this operating mode are not continuously updated,
but rather they form an enveloping curve from all the recorded measurements. In this way,
any changes that occur (e.g. temporary fault triggering) during continuous measurements
are rendered visible for the user.

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 Conducting measurements

Selecting the operating The menu with the TDR operating modes can be accessed directly from the main menu
mode and phases using the menu item and, depending on the equipment in the test van, it can include
the following menu items:
Menu item Operating mode
Normal pulse reflection measurement via the HV connection cable

Normal pulse reflection measurement via the optional LV connection

cable
IFL measurement via the HV connection cable

IFL measurement via the optional LV connection cable

Directly upon entering the operating mode, the phases to be tested are queried. The
phases must then be configured according to the actual connection situation.

When you select a single phase (for example L1 - N), a reflection measurement is
performed between the phase and the cable sheath. Here, not only the sought error is
visible, the connection sleeve and tee joints are as well. They can often be used for
orientation for fault location. For comparison purposes, additional individual phases can
be activated for the measurement as desired.

Once one of the type “L - L” options (for example L1 - L2) has been selected, a
differential measurement is performed between the two phases. In this mode the
reflections of both inputs are combined to form a single curve. However, the reflections
received at the second input have their polarity reversed through a differential
transformed. Consequently, the differential curve generated here then shows genuine
differences only. Faults of identical magnitude, all-core breaks or cable inhomogeneities
(such as joints) will not be visible because a difference does not exist.
After selection of the desired options, the phase selection menu must be
closed using . If necessary, the phase selection can be opened later and modified.

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Conducting measurements

Averaging In the operating modes and the averaging function can be activated or deactivated
using the menu item . When averaging is active, the curve shown on the display
presents the average of all previously recorded measurements. A maximum of 256
measurements are taken into consideration here. After reaching this figure, the recording
stops automatically.

The number of measurements taken into consideration for the averaging function is
shown at the bottom area of the display and it is continuously updated.

Performing After selecting the operating mode and the phases, proceed as follows to perform a pulse
measurements reflection measurement:
Step Action
1 Use the Teleflex menu (see page 68) to make suitable settings for the
diffusion speed, pulse width, pulse amplitude and filter and, if necessary
activate the averaging function (see above).
2 Start the measurement using the menu item .
3 Enable the voltage conditioning using the “HV ON” button.
Result: Continuous measuring pulses are coupled into the phases involved in
the measurement. Depending on the operating mode the recording curves
are either continuously updated or combined to form an enveloping curve.
5 Examine the recorded reflectogram for deviations (see page 67) and, if
necessary, use the available functions (see page 68) to improve the accuracy
and display of the curve.
In IFL mode, you may try to trigger an intermittent fault by appropriate means.
6 Stop the measurement using the menu item .
Result: The measurement is stopped and the current curve frozen. When
necessary, the measurement can be continued using menu item .

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 Conducting measurements

6.8 Pre-location of high-resistance cable faults -

In order to perform accurate pinpointing of the cable fault in as small a segment of the
cable route as possible, a thorough prelocation procedure should be conducted
beforehand. This achieves a significantly shorter total location time while also protecting
the cables.

High-resistance cable faults reflect the low voltage pulses of a normal pulse reflection
measurement either inadequately or not at all, so that the fault location cannot be
identified using the recorded reflectogram. In this event, several other pre-location
methods have established themselves, each of which combines a high-voltage process
with the pulse reflection method. All these methods force arcing at the fault location
through a “breakdown” caused by a sudden discharge of a charged capacitor or by
charging the cable. Because the fault assumes the state of a low-resistance cable fault
for a short time, its position can be measured beyond this period with a pulse reflection
measurement.

The fault position can also be pre-located with sufficient accuracy using the oscillating
travelling wave between the fault location and the measurement system that is triggered
after the voltage breakdown.

In some pre-location modes, the menu item can be used to specify the way the fault
breakdown is caused. The following options can be selected:

Surging The breakdown is forced through abrupt capacitive discharge of the

surge capacitor.
Charging With the surge switch closed, the surge capacitor and the connected
cable itself are charged to the required breakdown voltage. The
available surge capacity is thereby increased by the cable capacity,
which can be very useful for particularly slow cables.

6.8.1 Arc reflection measurement (ARM) -

Introduction The ARM method is suited for the pre-location of high-resistance cable faults on power
cables with a total length of up to 10 km. For faults with low ignition voltage (<50 kV), pre-
location should be started with this method.

When locating the fault position a reflectogram is taken first under normal conditions
(reference trace). The charged surge capacitor is then discharged suddenly into the cable
and 15 reflection measurements are carried out in the static arc caused by faulty ignition.
The user can then select the most suitable fault pattern from the 15 recorded patterns.

The direct comparison of reference and fault pattern usually makes possible immediate,
clear identification of the fault location, because, due to the reflection at the burning arc,
the fault pattern displays a significantly negative reflection at the fault location compared
to the functional image.

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Conducting measurements

Delay between TDR Before recording a fault trace, the user can manually configure the delay between two
measuring pulses successive pulses using the menu item . This type of delay however, should not be
confused with the trigger delay time (see next page), which only delays the first pulse.

In principle it is advisable to record the first series of fault traces with a default delay of
256 μs.

If required the delay can be varied to suit between 0 μs and 3.84 ms and a renewed faulty
ignition undertaken.

For a setting of 0 μs the pulses are triggered as quickly as possible one after the other.

The effect of a delay adjustment is best illustrated in the current curve following a voltage
flash-over:

Set trigger threshold

Trigger time

■ Triggering a measuring pulse

As can be clearly seen in the figure, an increase in the delay enables a “wider” period to
be mapped, in which the arc - under certain circumstances - is extinguished before igniting
again.

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 Conducting measurements

Adjusting trigger delay A user issued with Administration rights (see page 61) can use the menu item to
time adjust the delay time between the received trigger signal (configured trigger threshold
exceeded) and the actual start of the TDR measurement.

This is intended to give the ignition process at the fault position sufficient time to form a
stable arc.

Basically, the delay time is set to an ideal setting at the factory for the system configuration
and it should only be adjusted in exceptional cases (in very special measurement layouts)
and this should be conducted by experienced users only.

Any improper adjustment to the delay time poses the following risks:
• Delay time too short: The arc is unstable and the reflectogram is not
representative or it is faulty.
• Delay time too long: As the delay time increases the risk of conducting a
measurement in the decay curve’s zero crossing increases. The ignition
procedures repeated at this point in time can falsify the reflectogram. If the delay
time is excessively high there is also a risk that the arc may already be
completely extinguished.

6.8.1.1 ARM measurement up to 12 kV (with Surge Unit 3/6/12 kV)

Procedure Proceed as follows to perform a fault prelocation:

Step Action
1 When in the submenu activate the menu item .
2 Select the defective phase in the phase selection menu and close the
menu using .
3 Set the voltage range to 12 kV.
4 Use the Teleflex menu (see page 68) to make suitable settings for the
propagation velocity, pulse width, pulse amplitude and the filter.
5 Start recording the reference trace using the menu item .
6 Enable the high voltage using the “HV ON” button.
Result: Following a brief calibration procedure the reference trace is
shown on the display.
7 Check whether the recorded curve and, in particular, the marked end of the
cable match the expected result.
If necessary, use the available functions (see page 68) to improve the
accuracy and the display of the reference trace. Stop the measurement via
the menu item , as soon as you are satisfied.
8 Prepare the system for fault trace recording using the menu item .
9 Using the large range selector on the Surge Unit 3/6/12 kV, set the
required voltage range and turn the rotary knobs to set the surge rate
and the surge voltage to the left limit stop.
10 Switch on the Surge Unit 3/6/12 kV via the on/off switch and activate
the high voltage standby via the HV button .

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Conducting measurements

Step Action
11 Taking the required fault ignition voltage into consideration, set the surge
voltage on the Surge Unit 3/6/12 kV using the rotary knob and then
trigger a single shot using the menu item on the Teleflex VX.
Result: If a voltage flash-over occurs at the fault position, a second trace
(fault trace) is shown on the display.
If triggering failed to occur and a fault trace was accordingly not recorded, it
may be necessary to adjust the trigger threshold (on the Teleflex VX) or the
surge voltage (on the Surge Unit 3/6/12 kV) before triggering a further
surge.
12 Turn the rotary encoder to select one of the 15 recorded curves and
confirm your selection by pressing it briefly. The selected curve can be
changed using the menu item up until the next measurement is started
or the operating mode is changed.
Result: The red marking is automatically positioned at the location
identified as the fault position (at which the two curves diverge).

13 If necessary, use the available functions (see page 68) to optimise the
curve display (filter, amplification) and re-adjust the marked fault position.
Then read off the fault distance.
14 Switch off the high voltage using the menu item .

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 Conducting measurements

6.8.1.2 ARM measurement up to 50 kV (double surge unit)

Introduction In the double surge procedure, the fault is ignited using high voltage (25 / 50 kV surge
circuit). Due to the ionisation phase that occurs during the ignition, the available time
would however be insufficient to obtain a stable and meaningful fault trace. Consequently,
as soon as a sufficiently high and stable current flows, the surge unit 3/6/12 kV is
discharged into the static arc. In this manner, it is stabilised and the burn duration clearly
extended, which then makes a reliable measurement possible.

Wear ear protection

Surge operation can cause high and sudden noise levels. It is strongly
recommended to wear hearing protection during surge operation. Keep in
mind that this will limit the operators awareness for ambient dangers.

Procedure Proceed as follows to perform a fault prelocation:

Step Action
1 When in the submenu activate the menu item .
2 Select the defective phase in the phase selection menu and close the
menu using .
3 Set the voltage range to 50 kV.
4 Use the Teleflex menu (see page 68) to make suitable settings for the
propagation velocity, pulse width, pulse amplitude and the filter.
5 Start recording the reference trace using the menu item .
6 Enable the high voltage using the “HV ON” button.
Result: Following a brief calibration procedure the reference trace is
shown on the display.
7 Check whether the recorded curve and, in particular, the marked end of the
cable match the expected result.
If necessary, use the available functions (see page 68) to improve the
accuracy and the display of the reference trace. Stop the measurement via
the menu item , as soon as you are satisfied.
8 Prepare the system for fault trace recording using the menu item .
9 Taking the required fault ignition voltage into consideration, set the surge
voltage.
10 Using the large range selector on the Surge Unit 3/6/12 kV, set the
required voltage range and turn the rotary knobs to set the surge rate
and the surge voltage to the left limit stop.
11 Switch on the Surge Unit 3/6/12 kV via the on/off switch and activate
the high voltage standby via the HV button .
12 Select the voltage setting 3-6-12 on the surge unit 3/6/12 kV using the
rotary knob and lthen trigger a single shot using the menu item on
the Teleflex VX.

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Conducting measurements

Step Action
Result: If a voltage flash-over occurs at the fault position, a second trace
(fault trace) is shown on the display.
If triggering failed to occur and a fault trace was accordingly not recorded, it
may be necessary to adjust the trigger threshold or the surge voltage on
the Teleflex VX before triggering a further surge.
13 Turn the rotary encoder to select one of the 15 recorded curves and
confirm your selection by pressing it briefly. The selected curve can be
changed using the menu item up until the next measurement is started
or the operating mode is changed.
Result: The red marking is automatically positioned at the location
identified as the fault position (at which the two curves diverge).

14 If necessary, use the available functions (see page 68) to optimise the
curve display (filter, amplification) and re-adjust the marked fault position.
Then read off the fault distance.
15 Switch off the high voltage using the menu item .

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 Conducting measurements

6.8.2 Voltage decoupling (DECAY) -

Introduction The decay method is used to pre-locate high-resistance cable faults using a high fault
ignition voltage (<110 kV) in rechargeable cables.

To this end, the cable is charged with a DC voltage until the voltage exceeds the fault’s
breakdown voltage. The energy stored in the cable capacitance discharges through the
fault and generates a travelling wave, which is recorded and displayed by the system as
an attenuated oscillation. The period of this oscillation can be used along with the following
formula to determine the actual fault distance:

𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑

𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 = − 𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿ℎ 𝑜𝑜𝑜𝑜 𝐻𝐻𝐻𝐻 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐
2

Procedure Proceed as follows to pre-locate a cable fault using the DECAY method:
Step Action
1 When in the submenu activate the menu item .
2 Select the defective phase in the phase selection menu and close the menu
using .
3 Set the voltage range, taking the required fault ignition voltage into
consideration.
4 Use menu item or NVP to set the propagation velocity and then use menu
item to set the measuring range to roughly five to ten times the complete
length of the cable.
5 Start the measurement using the menu item .
6 Enable the high voltage using the “HV ON” button.

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Step Action
7 Increase the voltage to the desired test voltage using the rotary encoder and
confirm the value by pushing in the rotary encoder.
The dialogue for setting the voltage closes automatically after a few seconds
for safety reasons but it can be accessed again using the menu item .
Result: The test object is charged to the set voltage. Once the fault breaks
down, an attenuated and oscillating voltage curve is shown in the display and
the voltage conditioning is interrupted.

The software automatically attempts to calibrate a period of the oscillation and

to set corresponding markings.
8 Switch off the high voltage using the menu item .
9 If the recorded decay curve is superimposed to an excessive degree by
interference signals, it uses the available filter settings (see page 68) to
smooth the characteristic of the curve. Amplitudes that are too high can be
counteracted by reducing the amplification (see page 68).
Each time an adjustment is made, you must repeat the procedure from
Step 5.
10 If the automatically set markings do not enclose a period exactly, you can use
the function to correct their positions.
Half the distance of one period is shown directly next to the cursor and in the
bottom left corner of the display.

11 Subtract the length of the connection cable from this value and the internal
wring of the test van. This equates to a total of approx. 65 metres in the case
of a standard 50-metre cable drum.
The calculated value roughly corresponds to the distance between the
connection point and the fault. For technical reasons, this method has a
slightly higher tolerance than, for example, pre-location using the ARM
method.

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6.8.3 Current decoupling (ICE) -

Introduction Prelocation using current decoupling has established itself, particularly with regard to
faults in the lower kOhm range and for extremely large fault distances, in which the
ARM- method often fails to achieve any results.

As with the ARM method, an abrupt discharge of the surge capacitor triggers a breakdown
in the fault. Consequently, an attenuated transient wave moves back and forth between
the fault location and the measurement system. Inductively decoupling the current causes
the display of an oscillation, which has a period equivalent to a single fault distance.
However, the length of the pre-measuring cable still needs to be deducted from this
distance.

6.8.3.1 ICE prelocation up to 12 kV (with Surge Unit 3/6/12 kV)

Procedure Proceed as follows to pre-locate a cable fault using the ICE method:
Step Action
1 When in the submenu activate the menu item .
2 Select the defective phase in the phase selection menu and close the menu
using .
3 Set the voltage range to 12 kV.
4 Use menu item or NVP to set the propagation velocity and then use menu
item to set the measuring range to roughly five to ten times the complete
length of the cable.
5 Use the menu item to select whether the fault breakdown should be
forced by charging the cable or by triggering a surge discharge (see page 90).
6 Start the measurement using the menu item .
7 Enable the high voltage using the “HV ON” button.
8 Using the large range selector on the Surge Unit 3/6/12 kV, set the
required voltage range and turn the rotary knobs to set the surge rate and
the surge voltage to the left limit stop.
9 Switch on the Surge Unit 3/6/12 kV via the on/off switch and activate the
high voltage standby via the HV button .

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Step Action
10 Taking the required fault ignition voltage into consideration, set the surge
voltage on the Surge Unit 3/6/12 kV using the rotary knob and then trigger
a single shot using the menu item on the Teleflex VX.
Result: If a voltage flash-over occurs at the fault position, the display shows
an attenuated and oscillating current curve.

The software automatically attempts to calibrate a period of the oscillation and

to set corresponding markings.
If triggering failed to occur, and therefore a fault trace was not made, it may
then be necessary to adjust the trigger threshold or the surge voltage before
triggering a further surge.
11 Switch off the high voltage using the menu item .
12 If the recorded decay curve is superimposed to an excessive degree by
interference signals, it uses the available filter settings (see page 68) to
smooth the characteristic of the curve.
Amplitudes that are too high can be counteracted by reducing the
amplification (see page 68).
Each time an adjustment is made, you must repeat the procedure from
Step 6.

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Step Action
13 If the automatically set markings do not enclose a period exactly, you can use
the function to correct their positions.
The distance of one period is shown directly next to the cursor and in the
bottom left corner of the display.

14 Subtract the length of the connection cable from this value and the internal
wring of the test van. This equates to a total of approx. 65 metres in the case
of a standard 50-metre cable drum.
The calculated value roughly corresponds to the distance between the
connection point and the fault.
For technical reasons, this method has a slightly higher tolerance than, for
example, pre-location using the ARM method. With the ICE methods, often 5
… 10% larger distances are measured, which is why measurement
technicians should first walk toward the test van when pinpointing the pre-
located fault position.

6.8.3.2 ICE prelocation up to 50 kV or 80 / 100 kV (optional)

Procedure Proceed as follows to perform a fault prelocation:

Step Action
1 When in the submenu activate the menu item .
2 Select the defective phase in the phase selection menu and close the menu
using .
For operation in 80/100 kV mode, refer to the special notes on electrical
connection (see page 33) and phase selection (see page 51).
3 Depending on the fault ignition voltage set the voltage range to 25 kV or
50 kV (in 80/100 kV mode, the voltage range is automatically set to 80 or
100 kV).
4 Use menu item or NVP to set the propagation velocity and then use menu
item to set the measuring range to roughly five to ten times the complete
length of the cable.
5 Use the menu item to select whether the fault breakdown should be
forced by charging the cable or by triggering a surge discharge (see page 90).

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Step Action
6 Start the measurement using the menu item .
7 Enable the high voltage using the “HV ON” button.
8 Set the voltage, taking the required fault ignition voltage into consideration.
If the fault will be caused by surge discharge to breakdown, this needs to be
initiated using the menu item once the surge capacitor has been charged
to the set voltage.
If instead the cable should be charged to the fault breakdown, the system
starts immediately with voltage conditioning.
Result: If a voltage flash-over occurs at the fault position, the display shows
an attenuated and oscillating current curve.

The software automatically attempts to calibrate a period of the oscillation and

to set corresponding markings.
If triggering failed to occur, and therefore a fault trace was not made, it may
then be necessary to adjust the trigger threshold or the surge voltage before
triggering a further surge.
9 Switch off the high voltage using the menu item .
10 If the recorded decay curve is superimposed to an excessive degree by
interference signals, it uses the available filter settings (see page 68) to
smooth the characteristic of the curve.
Amplitudes that are too high can be counteracted by reducing the
amplification (see page 68).
Each time an adjustment is made, you must repeat the procedure from
Step 6.

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Step Action
11 If the automatically set markings do not enclose a period exactly, you can use
the function to correct their positions.
The distance of one period is shown directly next to the cursor and in the
bottom left corner of the display.

12 Subtract the length of the connection cable from this value and the internal
wring of the test van. This equates to a total of approx. 65 metres in the case
of a standard 50-metre cable drum.
The calculated value roughly corresponds to the distance between the
connection point and the fault.
For technical reasons, this method has a slightly higher tolerance than, for
example, pre-location using the ARM method. With the ICE methods, often 5
… 10% larger distances are measured, which is why measurement
technicians should first walk toward the test van when pinpointing the pre-
located fault position.

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6.8.4 Three-phase current decoupling (optional) -

Introduction Three-phase current decoupling is used to locate high-resistance and sporadic cable
faults in branched cables networks. The ignition voltage of the fault may not exceed
50 kV.

From the different known methods, the differential comparison method has proven itself
in particular for pre-location of faults in the branched low voltage network, which is why
the description in this section is based mainly on this method.

With the differential comparison method, in addition to the defective phase, an intact
phase must also be connected and activated. For comparison purposes, after a
measurement with open ends, additional measurements need to be performed in which
the cable ends (and later also the ends of the branches, if necessary) must be bridged.

Special features for the The system is equipped with various current couplers, which can catch the current from
phase selection one or more phases, depending on the connection configuration.

Accordingly, depending on the connected phases, the following signals are caught at the
various couplers:
Connected Additive Differential coupler
phases coupler
P1 P2 P3
S
L1 L1 L1 - L1
L2 L2 L2 L2 -
L3 L3 - L3 L3
L1, L2 L1+L2 L1-L2 L2 –L1
L1, L3 L1+L3 L1 –L3 L3-L1
L2, L3 L2+L3 –L2 L2-L3 L3

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In the phase selection menu, in addition to the connected phase, the current coupler to
be used must also be selected. This ensures that the desired sum or differential signal is
displayed as reflectogram.

Selection of the connected

phases used for fault location
(defective phase and intact
phase)

Selection of the current coupler to

be used. The information in
parenthesis indicates at which
coupler the required differential
signal can be measured.

For example, if a fault in phase L1 needs to be localised using the differential comparison
method and L2 will serve as the intact phase, the options L1 and L2 must first be activated.
The differential coupler P1 (option 1 [L1-L2]) must then be activated, over which the
differential signal between L1-L2 is decoupled.

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Procedure Proceed a follows to pre-locate a cable fault using the differential comparison method:
Step Action
1 When in the submenu activate the menu item .
2 In the phase selection menu, select the two phases involved in the
measurement and the current coupler over which the differential signal of
these two phases can be decoupled.
Please observe the instructions on previous pages.
Then close the menu using .
3 Carry out an ICE measurement in a suitable voltage range (see page 98).
4 Bridge the defective line and the intact line at the far end of the cable.
5 Prepare the software for recording a second reflectogram using the menu
item .
6 Carry out another ICE measurement (see page 98).
Result: A second reflectogram is shown that differs from the first diagram in
that the reflection directed from the fault location to the end of the cable now
runs back to the start of the cable via the bridge and the intact line, and when
it passes through the current coupler, an additional reflection is caused.

7 Switch off the high voltage using the menu item .

8 Based on the differential comparison method, determine the fault distance. If
the calculation indicates that the fault location is in a branch, another
measurement must be performed with the ends of the corresponding branch
bridged.

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6.8.5 ARM burning with the 15 kV burn down unit (optional) -

Introduction In ARM burning a continuous arc reflection measurement takes place during the burning
process that sets in after the fault breakdown. This enables any changes in the fault
caused by the burning process to be monitored on the screen.

As with the ARM method, the reference trace and the fault pattern are compared with
each other and the fault distance can be read off directly.

The advantage of this method compared with conventional burning is the controlled
procedure which restricts the actual burning to the shortest necessary time and by doing
so preserves the cable’s service life.

Procedure Proceed as follows to pre-locate a cable fault using the ARM burning method:
Step Action
1 When in the submenu activate the menu item / .
2 Select the defective phase in the phase selection menu and close the menu
using .
3 Use the Teleflex menu (see page 68) to make suitable settings for the
propagation velocity, pulse width, pulse amplitude and the filter.
4 Start recording the reference trace using the menu item .
Result: Following a brief calibration procedure the reference trace is shown
on the display.
5 Check whether the recorded curve and, in particular, the marked end of the
cable match the expected result.
If necessary, use the available functions (see page 68) to improve the
accuracy and the display of the reference trace then repeat the recording
using the menu item .
6 The menu item can be used to activate or deactivate an automatic switch-
off.
If automatic switch-off is activated, the measurement is automatically stopped
as soon as the fault position becomes clearly apparent during the burning
procedure when comparing reference and fault traces.
Otherwise the measurement has to be manually stopped.
7 Prepare the system for fault trace recording using the menu item .
8 Put the 15 kV burn unit unit into operation.

For information on operating the 15 kV burn unit, refer to the

corresponding operating manual.

9 Initiate the burning process using the burn down instrument and observe the
resulting fault conversion during the burning process on the screen of the
Teleflex VX.
Stop the measurement using the menu item , as soon as the fault position
becomes clearly apparent through the comparison of reference and fault
traces.
In this case, when the automatic switch-off is activated, the measurement is
automatically stopped.

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Step Action
10 If necessary, use the available functions (see page 68) to optimise the curve
display (filter, amplification) and re-adjust the marked fault position. Then read
off the fault distance.
11 Switch off the high voltage using the menu item .

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6.9 Burning

Purpose What is known as “burning” enables ongoing conversion of high-impedance faults into
low-impedance shunts right up to saturated short-circuits. Thanks to steady improvement
in prelocation methods, this material-stressing method must be used only very rarely with
difficult faults, such as with intermittent cable faults and moist cable faults.

6.9.1 Burning up to 110 kV (with internal voltage source)

Procedure Proceed as follows to perform a fault conversion:

Step Action
1 When in the submenu activate the menu item .
2 Select the defective phase in the phase selection menu and close the menu
using .
3 Set the desired voltage range.
4 If desired, limit the maximum burning time via the menu item .
5 Start the operating mode using the menu item .
6 Enable the high voltage using the “HV ON” button.
7 Slowly increase the voltage until it reaches fault ignition voltage using the
rotary encoder. The voltage will be ramped up to the set target value
immediately without prior confirmation!
The dialogue for setting the voltage closes automatically after a few seconds
for safety reasons but it can be accessed again using the U menu item.

Result: The high voltage source starts charging the cable up to the set
voltage. The voltage and current curves are shown on the display.
As soon as the fault is ignited, the voltage drops abruptly while the burning
current rises sharply.
A few minutes are usually enough to convert the fault resistance so that it may
be localised using an HV prelocation method.
8 As soon as you want to end the firing process Switch off the high voltage using
the menu item .

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6.9.2 Burning with the 15 kV burn unit (optional)

Procedure Proceed as follows to perform a fault conversion:

Step Action
1 When in the submenu activate the menu item .
2 Select the defective phase in the phase selection menu and close the menu
using .
3 Set the voltage range to 15 kV.
4 Start the operating mode via the menu item.
5 Enable the high voltage using the “HV ON” button.
6 Start the 15 kV burn unit and try to convert the fault resistance.

For information on operating the 15 kV burn unit, refer to the

corresponding operating manual.

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6.10 Fault pinpointing

Purpose The aim of every cable fault pinpointing is the precise location of the fault position to avoid
unnecessary excavation works.

Selecting the operating The two surge operating modes are grouped in the sub-menu . Using the menu
mode item , pure surge mode can be started, in which no curves are recorded or displayed.

For paper-insulated cables in particular, however, it can be helpful to be able to directly

track any changes in the ignition behaviour of the fault during surging. In this case, the
operating mode should be selected, which combines traditional surging with a pre-
location method (current decoupling). Here, the oscillating curve of the inductively
decoupled current is shown in the display during surge operation and refreshed with each
surge. If a change occurs, the refresh can be stopped manually at any time and the current
curve examined more closely. Surge mode continues unchanged.

6.10.1 Surge pinpointing up to 12 kV (with surge unit 3/6/12 kV)

Procedure Proceed as follows to perform fault pinpointing:

Step Action
1 When in the submenu activate the menu item or .
2 Select the defective phase in the phase selection menu and close the menu
using .
3 Set the voltage range to 12 kV.
4 Using the large range selector on the Surge Unit 3/6/12 kV, set the
required voltage range and turn the rotary knobs to set the surge rate and
the surge voltage to the left limit stop.
In order to achieve the highest possible surge energy, it is recommended to
select the smallest voltage range required to ignite the fault!
5 Use the menu item to select whether the surge discharges are to be
decoupled automatically or manually.
With automatic surge decoupling, the desired distance between two surges
(surge rate) can be set down to the second using the menu item .
6 Start the operating mode via the menu item.
7 Enable the high voltage using the “HV ON” button.
8 Switch on the Surge Unit 3/6/12 kV via the on/off switch and activate the
high voltage standby via the HV button .
9 Set the required surge voltage on the Surge Unit 3/6/12 kV using the rotary
knob .

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Conducting measurements

Step Action
10 Start surge operation via the menu item on the Teleflex VX.
Result: In time with the set surge rate, the system couples surge pulses into
the test object that result in flash overs at the fault position.
In manual surge mode, each surge discharge must be triggered manually via
the menu item.
11 Locate the precise position of the fault using a surge wave receiver (e.g.
Digiphone) in the area identified during the prelocation.

For information about operating the surge wave receiver, refer to

the associated operating manual.

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 Conducting measurements

6.10.2 Surge pinpointing up to 50 kV

Wear ear protection

Surge operation can cause high and sudden noise levels. It is strongly
recommended to wear hearing protection during surge operation. Keep in
mind that this will limit the operators awareness for ambient dangers.

Procedure Proceed as follows to perform fault pinpointing:

Step Action
1 When in the submenu activate the menu item or .
2 Select the defective phase in the phase selection menu and close the menu
using .
3 Set the voltage range to 25 or 50 kV.
4 Use the menu item to select whether the surge discharges are to be
decoupled automatically or manually.
With automatic surge decoupling, the desired distance between two surges
(surge rate) can be set down to the second using the menu item .
5 Start the operating mode via the menu item.
6 Enable the high voltage using the “HV ON” button.
7 Set the surge voltage, taking the required fault ignition voltage into
consideration.
8 Start surge operation via the menu item on the Teleflex VX.
Result: In time with the set surge rate, the system couples surge pulses into
the test object that result in flash overs at the fault position.
In manual surge mode, each surge discharge must be triggered manually via
the menu item.
9 Locate the precise position of the fault using a surge wave receiver (e.g.
Digiphone) in the area identified during the prelocation.

For information about operating the surge wave receiver, refer to

the associated operating manual.

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6.10.3 Surge pinpointing up to 80/100 kV (optional)

Wear ear protection

Surge operation can cause high and sudden noise levels. It is strongly
recommended to wear hearing protection during surge operation. Keep in
mind that this will limit the operators awareness for ambient dangers.

Procedure Proceed as follows to perform fault pinpointing:

Step Action
1 Put the test van into operation as described in chapter 3.
The electrical connection between cable reel HV3 and the patch panel is to be
carried in compliance with the special requirements of the “100 kV surging”
mode (see page 33).
2 When in the submenu activate the menu item or .
3 Select the defective phase in the phase selection menu and close the menu
using .
For operation in 80/100 kV mode, refer to the special notes on electrical
connection (see page 33) and phase selection (see page 51).
4 Use the menu item to select whether the surge discharges are to be
decoupled automatically or manually.
With automatic surge decoupling, the desired distance between two surges
(surge rate) can be set down to the second using the menu item .
5 Start the operating mode via the menu item.
6 Enable the high voltage using the “HV ON” button.
7 Set the surge voltage, taking the required fault ignition voltage into
consideration.
8 Start surge operation via the menu item on the Teleflex VX.
Result: In time with the set surge rate, the system couples surge pulses into
the test object that result in flash overs at the fault position.
In manual surge mode, each surge discharge must be triggered manually via
the menu item.
9 Locate the precise position of the fault using a surge wave receiver (e.g.
Digiphone) in the area identified during the prelocation.

For information about operating the surge wave receiver, refer to

the associated operating manual.

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6.10.4 Line and fault location with the audio frequency generator

Introduction The audio frequency generator, in combination with an appropriate audio frequency
receiver, is suitable for pinpointing of low resistance cable faults (field of twist method,
minimum turbidity method), for locating cables and metallic conductors (for example,
pipes) and for cable identification.

With automatic impedance matching, multi-frequency operation and SignalSelect

operating mode for showing the direction of flow, the generator provides a number of
features that facilitate location/identification and ensure reliable results.

Coupling to the cable When locating/routing metallic lines (e.g. cables, pipes), a signal return current must be
or metallic conductor ensured through contact with the ground or, if necessary, through connection to an
alternative conductor. One possible option is a direct connection to the cable shield. This
method eliminates the need for further switching operations at the other end of the cable.

If the shield cannot be isolated from earth at the connection point, the signal can also be
directly coupled to the inner conductor. In this case, however, it is recommended that the
inner conductor is grounded at the other end of the cable — especially at low frequencies.

Specific connection methods for locating sleeves and faults in twisted multi-
core cables are provided in the operating instructions for the audio frequency
receiver.

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Selecting the operating At the start of an audio frequency measurement, the submenu of the pinpointing operating
mode and phases modes must be opened using the menu item and from this, the menu item
accessed.

Directly upon entering the operating mode, the connected phase to be tested is queried.
The phase must then be configured according to the actual connection situation.

The phase selection menu must then be closed using . If necessary, the phase
selection can be opened later and modified.

Setting the operating In preparation of the actual measurement, the desired operating mode should be set first:
mode and the
measurement Operating Description
parameters mode
Sine wave mode
In this default mode, the currently set frequency is normally emitted as a
pure sine wave.
“SignalSelect” mode
In “SignalSelect” mode, a specially coded audio frequency signal is
emitted that identifies the direction of the signal flow, thus increasing the
accuracy and reliability of route tracing. The mode is thus perfectly suited
for routing of conductors in areas with lines that run close together.
Reliable identification of the coded signal can only be ensured when no
customer-specific frequencies are preconfigured on the audio frequency
generator, instead only the standard frequencies (see following table).
Multi-frequency mode
In multi-frequency mode, the frequencies f1, f2 and f3 are emitted parallel
and superimposed.

Depending on the set operating mode, the following parameters can be set:
Menu item Description
Setting of the output frequency with which the metallic conductor should
transmit.
By default, the frequencies 0.488 kHz (f1), 0.956 kHz (f2) and 8.867 kHz
(f3) are offered. Upon request, other/additional ones can be activated (in
total up to 5 frequencies between 0.400 and 9.999 kHz are possible).
Switch between continuous and pulse mode
In pulse mode, after 700 ms, the output signal is interrupted for 300 ms.
This timing can be useful for disturbed and superimposed signals in
order to be able to clearly identify your own signals.
Due to special coding of the output signal, in “SignalSelect” mode, no
pulsed signal can be emitted.

Starting audio Once all relevant parameters have been set, transmission along the metallic conductor
frequency transmission can be started using the menu item . Following this the high voltage must be authorised
using the “HV ON” button and the transmission power set. The dialogue for setting the
power level closes automatically after a few seconds for safety reasons but it can be
accessed again using the menu item .

As soon as high voltage is enabled, the “HV OFF” button lights up red signalling “high
voltage at the HV output”. The audio frequency signal is transmitted on the connected
conductor.

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Line and fault location During line and fault location, the test van must not be left unattended and accessible to
third parties.

The measurement technician who remains in the test van can maintain telephone contact
with their colleagues and if necessary modify the operating mode or frequency.

For line and fault location, any audio frequency receiver whose reception frequencies
match the frequencies of the generator is in principle suitable. For clear identification of
the specially coded “SignalSelect” signal (and thus the signal direction of flow), however,
an audio frequency receiver from the product assortment of Megger is necessary.

For detailed information on using the audio frequency receiver and the
various location methods, please read the accompanying instructions.

The safety of the test van that is in operation must be guaranteed at all
times by the persons responsible for the test van in accordance with the
applicable safety regulations and guidelines, also during line and fault
WARNING location!

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6.11 Dielectric diagnosis (optional)

Introduction Underground medium and high voltage cables are continuously subject to thermal,
electrical and mechanical stresses over the course of their use.

This fact inevitably leads − despite the use of durable materials − to increasing damage
or ageing of the cable, which in turn can lead to a measurable increase in dielectric losses.

A measure of these dielectric losses is the so-called loss factor tanδ, which can be
determined within the scope of a tan delta step test.

On the basis of the measurement results, integral ageing effects, such as the degree of
humidity, can be diagnosed and cables with critical ageing identified.

Prerequisites The operating mode is only available if TanDelta measurement is part of the purchased
function package and the measuring system has a test voltage source that can generate
sinusoidal test voltage.

Selecting the operating The operating modes for dielectric cable diagnosis can accessed ether direct from the
mode main menu or grouped in the sub-menu .

Menu item Operating mode

Monitored withstand test (sine wave voltage) with accompanying tan
delta measurement
Tan delta step test with automatic standard-compliant evaluation of
measured data

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6.11.1 Withstand voltage diagnosis

Setting the The phases and the voltage range are automatically queried when entering the operating
measurement mode, however − like all other settings − they can be adjusted until the actual start of the
parameters test.

The following test parameters can be set:

Button /
Description
Menu item
The first phase to be tested must be selected.
As soon as the testing of a phase has been completed, the phase
selection opens again automatically and testing can be continued directly
at the next phase with the same settings.
The phase selection menu must be closed after selecting the phase
using .
The test duration is shown in minutes. On expiry of the test duration, the
high voltage is switched off automatically.
Voltage range for the upcoming test. After starting the test, the actual test
voltage can only be set within this range.
This menu item is used to change the frequency of the VLF test voltage
(0.01 Hz to 0.1 Hz). The HD 620 S1 and HD 621 S1 harmonisation
documents recommend the 0.1-Hz frequency for VLF tests.
As the maximum permitted test frequency depends on the determined
cable capacitance and the test voltage being applied, it may be
necessary to adjust the test frequency set and about which the user was
informed at the start of the test.

Notes on selecting the The requirements for a meaningful cable test are found in the harmonisation documents
test voltage and test HD 620 S1:1996 and HD 621 S1:1996 and often in company-internal testing guidelines
time as well.

The following table provides a selection of proven test parameters for various applications:
Application Test voltage Test duration in
minutes
VLF test (initial use) 3Uo 15 to 60
VLF test (on aged cables) 1.7 … 3Uo 60

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Starting the test Once all the relevant parameters for the test as well as the phase(s) have been set, the
test can be started using the menu item. Following this the high voltage must be
authorised using the “HV ON” button and the test voltage set.

As soon as high voltage is enabled, the “HV OFF” button lights up red signalling “high
voltage at the HV output”.

At the start of the test, load detection is performed. If the load characteristics (capacitance
and insulation resistance) do not permit a test with the set test parameters, this is indicated
on the screen by a system message.

Testing using a lower frequency is offered where required. The user can then either cancel
the test or start it using a different frequency.

Performing the test The voltage curve can be followed on the screen during the test. After the test has started,
the measuring sensor generally needs about 3 cycles to adapt optimally to the current
and voltage level. Not until after this start-up phase will the tanδ values measured be
displayed as coloured symbols (as per the legend below the diagram) on the curve line.

You can use the menu item any time to display a table with the last 10 measured
values.

The test duration can be adjusted retrospectively even while the test is ongoing using the
menu item.

Alongside the voltage and tanδ values, some other relevant parameters and
measurement values are shown at the bottom edge of the screen.
Symbol Description

Remaining test duration

Set test duration

Actual test frequency

Measured load capacitance

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Symbol Description
Measured insulation resistance

Average of the individual measurement values so far

σ Standard deviation of the individual measurement values so far

Changing phases As soon as the testing of a phase has been completed, the phase selection opens again
during the course of automatically and another phase can be selected (if not all phases have been tested yet).
the test The phases which have already been tested are marked in green.

If wanted, the next phase to be tested can be selected and the electrical connection
adjusted accordingly. The high voltage source is automatically switched off and the HV
output is discharged.

WARNING
Follow the five safety rules
To establish and ensure a voltage-free state when changing phases, the
five safety rules must be followed (see page 9).

After changing the phase, the phase selection menu must be closed and the high voltage
must be enabled again with the “HV On” button. After doing so, the system automatically
continues with the measurement on the next phase.

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Finishing the test If a test time was defined, the high voltage is automatically switched off at the end of this
time.
The measurement can be manually deactivated at any time via the “HV OFF” button or
the menu item. A measurement which has been suspended this way can be resumed
as long as the operating mode has not been exited in the meantime. The query at to
whether the measurement should be continued or restarted will appear immediately after
selecting the menu item.
When resuming a measurement, the voltage run of the last phase measured begins from
the start. This way, any confusion about phase changes can be corrected without having
to start the complete measurement from the start all over again.

If a voltage breakdown occurs in the test object during the test duration, the measurement
is also interrupted.

Irrespective of whether the high voltage is switched off automatically or manually, the HV
output is discharged and earthed. The test data logged up to the switch-off are recorded
in the history database (see page 52).

Evaluation of the test A dielectric strength test carried out to standard is generally deemed to have been
results successfully passed if there are no break-downs in the test object throughout the duration
of the test. In addition to this clear statement, further conclusions can be drawn on the
state of the test object using the trend over time of the measured tanδ values.

E.g. a falling measured tanδ value can indicate damp cables / fittings, while a tanδ
increasing over time can be a definite indication of an emerging cable fault.

In the event of such a change in the measured values during the test it is strongly
recommended that you carry out a tan delta step test following the test (see next section).
The measurement results from this can be assessed using the relevant standards and will
provide an even more accurate conclusion as to the ageing of the cable insulation.

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6.11.2 Tan delta step test

6.11.2.1 Preparing the step test

Automatic query of As soon as the operating mode has been selected using the menu item, the
information information relevant for the measurement is queried in the following order:
Information Description
Phases The first phase to be tested must be selected.
As soon as the testing of a phase has been completed, the phase
selection opens again automatically and testing can be continued
directly at the next phase with the same settings.
The phase selection menu must be closed after selecting the phase
using .
Nominal Uo nominal voltage of the connected test object as an effective value.
voltage Once the value is confirmed, a calculation of the respective voltage
values of the individual steps is carried out and displayed on the screen.
You can use the menu item to amend the selection made right up
until the actual start of the measurement.

The maximum nominal voltage that can be set depends on the

maximum output voltage of the test system as well as on the set
voltage levels (see the next page).
If the nominal voltage of the cable is above the maximum value
that can be set, the number of the voltage levels would have to
be reduced accordingly first.

Insulation Should no evaluation criteria for the insulation type selected exist in the
type currently preset standard, the corresponding message will appear after
the selection has been made.

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Setting the Once you have entered the operating mode you can use the menu item to access a
measurement sub-menu where you can adjust advanced measurement settings.
parameters
Changing these parameters can have a considerable effect on the total test
duration! It is therefore recommended to check the estimated total test duration
after performing any changes. This is displayed in the lower portion of the
screen next to the icon and is updated with every change.

The following parameters can be modified:

Menu item Description
Number of the voltage levels (1 to 6) that the test voltage runs through in
the course of a step test.
The first voltage level is 0.5Uo. The voltage is increased by 0.5Uo with
every additional voltage level. The sixth voltage level would accordingly
be 3Uo.
A requirement for the automatic evaluation of the test results is that the
measurements were taken in respect of at least 3 voltage levels.
Once the value is confirmed, a calculation of the respective voltage
values of the individual steps is carried out while taking the nominal
voltage into account and displayed on the screen.

In practice, 4 levels with voltages of 0.5Uo, 1Uo, 1.5Uo and

2Uo have proven useful.
To avoid possible breakdowns, it is recommended that already
heavily aged cables not be measured at voltage levels greater
than 2Uo (≤1.5Uo is even safer).

Number of tanδ measured values (5 to 20) per voltage level.

At least 8 measured values per voltage level should be recorded in order
to obtain a calculated tan δ mean value that is statistically meaningful.
The more measured values that are utilised, the more reliable the
calculated mean. However, the stress placed on the test object also
increases accordingly. As the goal is a non-destructive diagnosis, the
number of measured values, especially in the case of high test voltages,
should be kept to as small a number as possible (recommended: 8 to 10
values).

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Menu item Description

Frequency of the VLF test voltage (0.01 Hz to 0.1 Hz).
A setting of 0.1 Hz is definitely recommended, since all the experience
documented in the relevant technical literature or in the corresponding
standards refer to this frequency as the diagnostic frequency.
By measuring at different frequencies, a tan δ spectrum can furthermore
be shown for the test object. This spectrum can provide further
information on the condition of the test object.

If the capacitance of the connected test object does not permit

a measurement using 0.1 Hz and an automatic frequency
adjustment is performed, the evaluation criteria that are
independent of frequency should be looked more closely.
These include, amongst others, the deviation of the absolute
tan δ values between the phases of a cable system and the
change of the tan δ with increasing voltage (Δ tan δ).

Only visible after obtaining administration rights (see page 61)

You can use this menu item to activate or disable averaging for
smoothing the measurement curve. Doing so will result in the display of
the average value of the last 3 values measured in the diagram rather
than the tanδ value actually measured.
Averaging does not take place beyond two voltage levels. Accordingly
the first two measured values of each voltage level are not shown when
averaging is activated.

If averaging is activated then automatic analysis of the

measurement results is not possible. Furthermore, the duration
of the voltage strain is increased. As such it is generally
recommended that you only activate this function in the event
of a significant fluctuation in measurement values.

Only visible after obtaining administration rights (see page 61)

This menu item can be used to adapt the voltage levels (as multiples of
Uo) for the individual voltage stages to your individual needs.
In practice, a voltage increase of 0.5Uo between two stages as proven
itself useful.
In addition, the two voltage stages, from which the Δtanδ (see page 132)
is calculated, can be modified.

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Menu item Description

Only visible after obtaining administration rights (see page 61)
This menu item can be used to activate or disable a safety function which
monitors the progression of the measured tanδ values during the
measurement process and highlights any dubious variations. The
measurement can then be suspended or continued. If the measurement
is continued, a non-destructive diagnosis can no longer be guaranteed.
Primarily, the safety function is used to catch “water trees” before they
turn into “electrical tress” and thus avoid a breakdown of the insulation.
This effect, intentionally provoked by a VLF test, should of course be
avoided in order to obtain a diagnosis that is as non-destructive as
possible.
If necessary, the dialogue window can be used to adapt the various
triggering thresholds of the safety function. Here a differentiation is made
between deviations from the moving average (average out of the last
three measured values) and from the statistical average (average out of
all measured values of the voltage level).

6.11.2.2 Performing the step test

Test start Once all the relevant parameters for the measurement as well as the phase(s) have been
set, the test can be started using the menu item . Following this the high voltage must
be authorised using the “HV ON” button and the test voltage set.

As soon as high voltage is enabled, the “HV OFF” button lights up red signalling “high
voltage at the HV output”.

At the start of the measurement, load detection is performed. If the load characteristics
(capacitance and insulation resistance) do not permit a measurement with the set test
parameters, this is indicated on the screen by a system message.

Measurement using a lower frequency is offered where required. The user can then either
cancel the measurement or start it using a different frequency. However, the latter would
result in the measurement being non-compliant and would prevent any automatic
evaluation of the measurement results from being carried out.

Alternatively, the number of voltage levels could be reduced, resulting in an automatic

drop in the maximum necessary test voltage. However, care should be taken here to
ensure that, if possible, the 3 voltage levels required for meaningful measurement results
are retained.

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Performing the The test voltage flows through the selected number of voltage levels during the course of
measurement the measurement and remains at a voltage level for the selected number of measured
values.

The measuring sensor generally needs about 3 cycles to adapt optimally to the current
and voltage level after the measurement has started. Not until after this start-up phase
will the tanδ values measured be displayed as coloured symbols (as per the legend below
the diagram) on the curve line.

You can use the menu item any time to display a table with the last 10 measured
values.

Alongside the voltage and tanδ values, some other relevant parameters and
measurement values are shown at the bottom edge of the screen.
Symbol Description

Estimated total test time

Actual test frequency

Measured load capacitance

Measured insulation resistance

Δ Difference of the tanδ mean values for two specified voltage levels (default:
Level 3 – Level 1)

σ Standard deviation of the individual measurement values so far

Status of the safety function (see page 122)

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Changing phases As soon as the testing of a phase has been completed, the phase selection opens again
during the course of automatically and another phase can be selected (if not all phases have been tested yet).
the test The phases which have already been tested are marked in green.

If wanted, the next phase to be tested can be selected and the electrical connection
adjusted accordingly. The high voltage source is automatically switched off and the HV
output is discharged.

Follow the five safety rules

To establish and ensure a voltage-free state when changing phases, the
five safety rules (see page 9) must be followed.
WARNING

For measurements with leakage current compensation (only available for external test
attachment), it should be noted that a different phase might need to be used for the
transport of the leakage current if the previously used phase will be measured next. In this
case, the electrical connection must be adjusted at the near and far cable ends.

After changing the phase, the phase selection menu must be closed and the high voltage
must be enabled again with the “HV On” button. After doing so, the system automatically
continues with the measurement on the next phase.

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Completing the test After all the set phases have run through the voltage levels, the measurement process
ends automatically and high voltage is switched off.

The measurement can be manually deactivated at any time via the “HV OFF” button or
the menu item. A measurement which has been suspended this way can be resumed
as long as the operating mode has not been exited in the meantime. The query at to
whether the measurement should be continued or restarted will appear immediately after
selecting the menu item.
When resuming a measurement, the voltage run of the last phase measured begins from
the start. This way, any confusion about phase changes can be corrected without having
to start the complete measurement from the start all over again.

If a voltage breakdown occurs in the test object during the test duration, the measurement
is also interrupted.

Irrespective of whether the high voltage is switched off automatically or manually, the HV
output is discharged and earthed. The test data logged up to the switch-off are recorded
in the history database (see page 52).

If all the conditions for an automatic evaluation of measurement results (see page 129)
are met, this is shown straight away upon completion of the measurement:

Instead of the voltage curve, the diagram area now shows the tan delta trend view across
all voltage levels and phases. The values form the mean value of the tanδ values
measured at the respective voltage level. The following illustration shows, by way of
example, a trend view over five voltage levels for all three phases:

You can use the menu item to switch back from this trend view to the standard
diagrams.

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6.11.2.3 Automatic evaluation of the test results

Requirements An automatic evaluation of the test results is only carried out if the following requirements
have been fulfilled:
• A standard for the evaluation of the test results has been selected.
• The selected standard contains criteria for the evaluation of the insulation type
of the connected cable.
• The test was conducted in respect of at least 3 voltage levels.
• The test was carried out on a test voltage with a frequency of 0.1 Hz.

Displaying the If the software was able to carry out an automatic evaluation, this will be shown together
evaluation with the resulting recommendations for action straight away following completion of the
measurement.

Using the following menu items shown in the sub-menu you can adjust the evaluation
criteria even after the measurement and display the evaluation again.
Symbol Description
Standard according to which the recorded measurement results should be
evaluated. In the manual setting there is no automatic evaluation.
Insulation type of the connected cable. Automatic evaluation is not possible
in the mixed setting.
Menu item for displaying the automatic evaluation and recommendations
for action.
If automatic evaluation is not possible, the non-fulfilled requirements are
indicated instead.

If the measurement has been performed at a varying frequency or with too few voltage
levels, it must either be repeated or the measurement results must be evaluated manually
(see page 132).

The evaluation criteria may be adapted as many times as required.

If, for example, the criteria of a stored standard have been adapted on account
of new findings (see next section), even past measurement results can be re-
evaluated thanks to the History database (see page 52).

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6.11.2.4 Setting your own evaluation criteria

Introduction With IEEE 400.2 (2Uo) and IEEE 400.2 (1.5Uo) the key standards for evaluating
measurement results are already implemented in the software.

Furthermore, the software features an assistant which allows customised evaluation

criteria to be specified and to be stored as an 'in-house' standard.

You may only create, edit and delete your own standards upon acquiring the
administration rights (see page 61).

Creating a custom Proceed as follows to create a custom standard:

standard
Step Action
1 In the submenu , select menu item .
2 Select Create standard.
3 Enter a descriptive name for the new standard and then select the Next
button.
4 Mark all the types of insulation for which you wish to store evaluation criteria in
this standard.
5 Mark all the evaluation criteria (see page 132), which should be included in the
evaluation of the condition and then select the Next button.

Select the evaluation criteria with care. As soon as just one of the
criteria has exceeded the specified threshold, the condition of the
cable insulation will be given a poorer evaluation. An evaluation based
on several criteria can therefore be more severely affected by
measurement inaccuracies.

6 For every combination of insulation type and evaluation criterion, enter the
lower and upper threshold for the condition description aged and then select
the Next button.
7 After entering all thresholds, save the new standard using the menu item
Finish.
The new standard can now be selected as the basis for evaluation for each
measurement using the menu item .

Editing a custom Proceed as follows to edit a custom standard:

standard
Step Action
1 In the submenu , select menu item .
2 Mark the standard you wish to edit.
3 Select the Edit standard button.
4 Proceed the same way as under steps 3–7 describing the procedure for
creating a new standard (see above).

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Deleting a custom Proceed as follows to edit a custom standard:

standard
Step Action
1 In the submenu , select menu item .
2 Mark the standard you wish to delete.
3 Select the Delete standard button.
4 Confirm the prompt with Yes.

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6.11.2.5 Manual evaluation of the test results

Introduction An automatic evaluation of the measurement results made by the software should be
understood as a valuable tool, however by no means should it be used as a sole decision-
making criterion.

Criteria such as deviating measurement results within a cable system, the influence of
leakage currents as well as outside influencing parameters can only be analysed to a
limited extent by software. The technician performing the test is therefore urged to
scrutinize the evaluation critically and, if necessary, to conduct own analyses to avoid
incorrect conclusions.

Evaluation criteria After completing a test, an overview of the following evaluation criteria derived from the
individual tan δ values can be called up by selecting the menu item :
Criterion Description
tanδ at xUo The mean value of the measured absolute tanδ values is specified
separately for each voltage level.
The condition should not however be evaluated solely on the basis of
these absolute values since these may be influenced by the following
factors:
• Number of sleeves in the cable stretch
• Type of sleeves
• Temperature of the cable
• Air humidity
• Leakage current over the terminators

Nevertheless, important information can be derived from the mean

value. For example, a comparison can be made of the values for all
three phases of a cable system under identical conditions. As a rule,
all three phases of a cable stretch are subject to the same conditions.
They have the same number of mountings and are subject to the
same environmental influences. By taking the measurements within a
short time frame, an almost uniform cable temperature can also be
ensured.
Consequently, the mean values of the three phases should be almost
identical. Substantial deviations upwards indicate that the condition of
the affected phase is poor. In such a case further investigations should
be made (e.g. a TE measurement).
σ The standard deviation σ is specified separately for each voltage level
and is a measure of the distribution of the individual tan δ values
around the mean value of the respective level.
1.5Uo–0.5Uo The most important criteria for a meaningful evaluation of the
(Δtanδ) insulation condition is the Δ tan δ, which reflects the voltage
dependency of the tan δ.
The Δ tan δ is calculated from the difference between the tan δ mean
value of the voltage levels 0.5U0 and 1.5U0.

Δ tan δ = tan δ1.5·Uo – tan δ0.5·Uo

The Δ tan δ can only be furnished in respect of measurements taken

in respect of at least 3 voltage levels.

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Evaluation of XLPE For XLPE cables, an insulation in good condition is indicated by a low Δtanδ, which
cables corresponds to a nearly constant tanδ over increasing test voltages. For an aged
insulation, the tanδ value increases slightly with increasing voltage. For a critically aged
insulation, the tanδ value clearly increases with increasing voltage.

Using the relevant literature as an aid, the absolute tanδ values measured on a XLPE
cable (homopolymeric) can also be used to derive conclusions about the condition (with
the restrictions presented on the previous page). The IEEE 400.2 - 2013 differentiates
between different regions of the world. For countries outside of North America, the
following limit values apply:
Mean value σ at Uo Δtanδ Condition assessment
at 2Uo (2Uo – Uo)
[10-3] [10-3] [10-3]
<1.2 and <0.1 and <0.6 No action required
1.2 bis 2 or 0.1 bis 0.5 or 0.6 bis 1 Further study advised
>2 or >0.5 or >1 Action required

For the North American area, however, significantly higher limit values are defined due
to differences in the design of the cables:
Mean value σ at Uo Δtanδ Condition assessment
at Uo (1,5Uo – 0,5Uo)
[10-3] [10-3] [10-3]
<4 and <0.1 and <5 No action required
4 to 50 or 0.1 to 0.5 or 5 to 80 Further study advised
>50 or >0.5 or >80 Action required

Evaluation of PILC The interpretation of the dielectric loss factor in evaluating the condition of PILC cables
cables has not yet been thoroughly investigated. An exact, qualitative evaluation can therefore
only be derived to a limited extent from the measurement results received, as compared
to XLPE cables.

In principle, it can be said that the dielectric loss factor of a PILC cable is always
considerably higher than that of a XLPE cable. Even a vulnerable XLPE cable will show
lower tanδ absolute values measured as compared to a healthy PILC cable.

The IEEE 400.2 - 2013 differentiates between different regions of the world. For countries
outside of North America, the following limit values apply:
Mean value σ at Uo Δtanδ Condition assessment
at 2Uo (2Uo – Uo)
[10-3] [10-3] [10-3]
<50 and <-0.5 and -20 to 20 No action required
50 to 100 or 0.5 to 1 or -20 to -50 or Further study advised
20 to 50
>100 or >1 or <-50 or >50 Action required

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 Conducting measurements

For the North American area, however, significantly higher limit values are defined due
to differences in the design of the cables:
Mean value σ at Uo Δtanδ Condition assessment
at Uo (1,5Uo – 0,5Uo)
[10-3] [10-3] [10-3]
<85 and <0.1 and -35 to 10 No action required
85 to 200 or 0.1 to 0.4 or -35 to -50 or Further study advised
10 to 100
>200 or >0.4 or <-50 or >100 Action required

Evaluation of EPR EPR cables by their nature exhibit a higher dielectrical loss factor as compared to XLPE
cables cables. However, this still lies below the level of PILC cables.

The threshold values given in the following table are to be regarded merely as guiding
values:
Mean value σ at Uo Δtanδ Condition assessment
at Uo (1,5Uo – 0,5Uo)
[10-3] [10-3] [10-3]
<35 and <0.1 and <5 No action required
35 to 120 or 0.1 to 1.3 or 5 to 100 Further study advised
>120 or >1.3 or >100 Action required

You can find a detailed breakdown of EPR insulations by material composition in the IEEE
standard IEEE 400.2 - 2013.

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6.12 Partial discharge diagnosis (optional)

The test accessory can also be used for partial discharge diagnostics. A prerequisite for
this is that the test van has a suitable partial discharge diagnostic system.

To perform a partial discharge diagnosis, menu item must either be opened directly
from the main menu or from submenu . Any further operating actions must be
performed using the “PD Detector” software (on provided notebook).

Detailed information on the operation of the “PD Detector” software can be

found in the operating manual for the partial discharge measurement system.

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6.13 Sheath test and sheath fault location with the MFM 10-M /
HVB 10-M (optional)

Requirements The test van must be equipped with an MFM 10-M sheath fault location system or an
HVB 10-M high voltage measuring bridge.

Purpose The MFM 10-M as well as the HVB 10-M allow the operator to check cable sheaths in the
easiest manner possible, as well as the prelocation and pinpointing of sheath faults with
a bipolar test voltage of up to 10 kV.

Procedure Proceed as follows to perform sheath testing or sheath fault locating:

Step Action
1 Put the test van into operation as described in chapter 3.
Use the MFM/HVB connection cable (see page 35) for the connection to the
test object.
2 When in the submenu activate the menu item .
3 Select the connected phase in the phase selection menu and close the menu
using .
4 Start the operating mode via the menu item.
5 Enable the high voltage using the “HV ON” button.
6 Switch on the MFM 10-M or the HVB 10-M and carry out the desired tests.

For information on operating the MFM 10-M or the HVB 10-M, refer
to the corresponding operating manual.

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6.14 Completing the work

After the measurements on a cable system has been completed and the high voltage has
been switched off (see page 43), the test van can be switched off by pressing the main
switch button on the Control Panel.

When disconnecting the test system, proceed in reverse sequence to the manner in which
the connection (see page 26) was made. While doing so, the following safety instructions
must be strictly adhered to.

WARNING
Danger from electric shock!
• Follow the five safety rules (see page 9).
• Even if switched off properly and discharged via the discharge device,
the system components that were under voltage should only be
touched once they have been discharged using a suitable discharge
rod as well as having been earthed and short-circuited.
• Only undo the earthing and short-circuiting measures when the test
object is to be operated again.
• Directly after completion of a partial discharge measurement, the PD
coupling unit must be short circuited using the short-circuit line or any
available earthing jacks, to prevent charging of the capacitor.

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 Exporting and processing measurement data

7 Exporting and processing measurement data

After the actual measurement job, the recorded measurement data can be conveniently
analysed, archived and summarised in a report on a Windows PC.

To do this, the desired data must first be marked for export in the History database (see
page 52) and then exported to an inserted USB flash drive via the data menu (see page
58). On the Windows PC, the data can then be imported into the protocol software and
processed further. Depending on the version of the protocol software, the following
functions are available:

Megger Book Lite Megger Book

(full version)
(free download on the Megger website) (article number: 2015875)

Analysis of the measurement

data with practical tools
Creation of a report based
on extensively customisable
report templates
Creation and maintenance of
a cable database
Archiving of measurement
activities in the data stock of
the respective cable

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 Troubleshooting

8 Troubleshooting

Fault messages A range of error messages can occur at the Teleflex VX during measurement, which can
be assigned to the following error categories:

- Procedure could not be completed because of a timeout

- Overvoltage determined at a surge capacitor

- Switching procedure could not be carried out or completed

- A shortfall of the minimum gas pressure in the HV motor switch or in the discharge
and earthing switch has been detected.

WARNING
Danger of electric breakdown
If a non-permissibly low gas pressure is signalled for one of the
two switches, its inner dielectric strength is no longer
guaranteed at extremely high voltages. No voltage > 50 kV may
be generated with the system until the gas in the affected switch
has been refilled by an authorised service centre.

In the event of a malfunction, the test van must be switched off taking the five safety rules
(see page 9) into consideration. Discharging of the test van and the test object is not
guaranteed in this case, and must be carried out manually using a suitable discharge rod
if necessary!

Behaviour at The equipment may only be used when working properly. When irregularities or
malfunction of normal malfunctions appear that cannot be solved consulting this manual, the equipment must
operation immediately be put out of operation and marked as not functional. In this case inform the
person in charge who should inform the Megger service to resolve the problem. The
instrument may only be operated when the malfunction is resolved.

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 Troubleshooting

Checking the fuses If a failure occurs in the power supply of the individual devices or peripherals, the positions
of the circuit breakers and the fuses should first be checked.
The fuses of the measuring system are located in the leg area below the Teleflex VX and
arranged as follows:

F1 F2 F3 F4 F5 F6 F7 … F15

Fuse Rating Protection

F1 2 x 25 A Mains input
F2 25 A Generator input
F3 16 A Air conditioning system, fan heater
F4 16 A Plug socket
F5 16 A Mains HV devices
F6 FI circuit breaker, plug sockets, charger, air conditioning
system
F7 2,5 A 24 V power supply 1 to supply safety circuit and motor
control
F8 2A Main switch
F9 4A Battery charger
F10 8A 24 V power supply 2 to supply the PLC (programmable
logic controller)
F11 1A PCB U/I transducer and PCB EL/PE
F12 4A Teleflex VX, control of high voltage source
F13 4A PLC
F14 8A Safety circuit
F15 6,3 A Motor control unit

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Troubleshooting

Especially in the event of power supply problems, the fuses in the NAS 60-3 mains supply
system should also be checked. This is located at the end of the mains cable.

Fuse Value Function

F1/F2 DG MOD 275 Overvoltage protection
F3 C2 Voltage monitoring
F4 RCD C32/0.3 A Test van main circuit
F5/F6 (inside the T1A Indicator lights on the NAS 60-3
housing)

Some other relevant 12 or 24 V circuits (e.g. vehicle interior lighting, cable drum motor)
are protected by the vehicle fuses.

CAUTION
If a circuit breaker or fuse is tripped repeatedly, it must be assumed that
there is a permanent fault in the affected circuit. To prevent additional
damage, further operation of the test van is not allowed.

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 Care and Maintenance

9 Care and Maintenance

9.1 Required maintenance by a service workshop

A measurement system of the technical complexity of the System R 30 needs regular

maintenance to maintain its functionality. For this reason it is imperative to perform a
maintenance upon occurrence of one of the following conditions:
• Once a year (check of the HV components, the safety devices, the insulating
gas and the individual devices / accessory parts)
• In case of malfunctions
• If the gas pressure in the HV motor switch or discharge and earthing switch
drops below the minimum threshold

Upon occurrence of any of these conditions, promptly contact the responsible service
workshop to make an appointment for maintenance.

If the maintenance requirements described above are not fulfilled, the

manufacturer releases itself from the warranty on defects shown to be due to
inadequate maintenance.

9.2 Maintenance work you can carry out yourself

To identify possible problems at an early stage and keep the system in good condition,
you must carry out the following tasks yourself at appropriate intervals depending on use:
• Remove dust and dirt
• Check the function of door and EMERGENCY OFF switches
• Unwind the cables and inspect for cracks and damage
• Check connecting cables and HV components for secure hold

For information on do-it-yourself maintenance and care of peripheral devices,

read the corresponding sections in the relevant operating manuals. This
especially applies to battery-powered devices.

If you find any defects during the test, promptly inform a service workshop
authorised by Megger.

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Care and Maintenance

143