High Voltage Engineering Lab

EE 422

Lab Manual

Student Name

Registration #

Department Of Electrical Engineering

Course Instructor: Engr. Hafiz Ghulam Murtaza Qamar

Lab Instructor: Engr. Muhammad Qamar ud Din

College of Engineering & Technology

University Of Sargodha
 LIST OF EXPERIMENTS

Lab Title CLO

1 Generation and measurement of AC voltage. 1,4

2 Generation and measurement of AC voltage through oscilloscope. 1,4

3 Generation and measurement of AC voltage through sphere gaps. 1,4

4 Understand Generation and measurement of DC voltage through oscilloscope 1,4

5 Generation and measurement of DC voltage through oscilloscope 2,4

6 Voltage doubler circuit. 2,4

7 Polarity effect and insulation screen. 2,4

8 Generation and measurement of impulse voltage. 2,4

9 Generation and measurement of impulse voltage using trigger sphere gap. 2,4

10 Disruptive discharge voltage tests with alternating current. 3,4

11 Disruptive discharge voltage tests with direct current. 3,4

12 Lighting impulse disruptive discharge test. 3,4

13 Insulation test for transformer oil. 3,4

RELEVANT PROGRAM LEARNING OUTCOMES (PLOs):
The course is designed so that students achieve following PLOs:

1 Engineering Knowledge: √ 7 Environment and Sustainability:

2 Problem Analysis: √ 8 Ethics:
3 Design/Development of Solutions: 9 Individual and Team Work: √
4 Investigation: √ 10 Communication: √
5 Modern Tool Usage: 11 Project Management:
6 The Engineer and Society: 12 Lifelong Learning:

COURSE LEARNING OUTCOMES:

Upon successful completion of the course, the student will be able to:

No. Description PLOs

CLO-1 To recognize the usage of control desk, testing transformer, safety 1
precautions and analytical system tool.
CLO-2 Assemble and examine High voltage, impulse voltage generation and 4
measurement of performance

CLO-3 Express knowledge and analysis of disruptive discharge voltages 2

CLO-4 Write lab notes, effective communication and the design & analysis of 9,10
the given problem, to perform in the laboratory environment as
individual & team.

Mapping of CLO’s to PLO’s

Course Program learning outcomes (PLO’s)

outcomes 1 2 3 4 5 6 7 8 9 10 11 12
CLO-1 √
CLO-2 √
CLO-3 √
CLO-4 √ √
 COLLEGE OF ENGINEERING & TECHNOLOGY
UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab Manual
Safety Regulations and Introduction to Control Desk, And Associated
Apparatus

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, M Hamza

Introduction
Experiments with high voltages could become particularly hazardous for the participants
should safety precautions be inadequate. To give an idea of the required safety measures, an
example the safety regulations followed in several high voltage laboratories attached to the
Technical University of Braunschweig shall be described below. These supplement the
appropriate safety regulations and as far as possible prevent risks to persons. Strict
observance is therefore the duty of everyone working in the laboratory. Here, any voltage
greater than 250 V to earth potential is understood to be a high voltage (VDE 0100).
Fundamental Rule
Before entering a high-voltage setup area, participants must first ensure that all conductors
which can assume high potential and lye in the contact zone are earthed and that all main
leads are interrupted.
Fencing
All high-voltage setups must be protected against unintentional entry to the danger zone. This
is appropriately done with the aid of metallic fences. When setting up the fences for voltages
up to 1 MV the following minimum clearances to the components at high voltage should not
be exceeded:
Alternating and direct voltages 50 cm for every 100 kV
Impulse voltages 20 cm for every 100 kV
A minimum clearance of 50 cm shall always be observed, independent of the value and type
of voltage. For voltages over 1 MV, in particular for switching impulse voltages, the values
quoted could be inadequate; special protective measures must then be introduced.
The fences should be reliably connected conductively, earthed and provided with warning
boards inscribed: “High Voltage! Caution! Highly Dangerous!”. It is forbidden to introduce
conductive objects through the fence while the setup is in use.
Safety locking

In high-voltage setups each door must be provided with safety switches; these allow the door
to be opened only when all main leads to the setup are interrupted. Instead of direct
interruption, the safety switches may also operate the no-voltage relay of a power circuit
breaker, which on opening the door, interrupts all the main leads to the setup.

These power circuit breakers may also be switched on again when the door is closed. For
direct supply from a high-voltage network (e.g. 10 kV city network), the main leads must be
interrupted visibly before entry to the setup by an additional open isolating switch. The
switched condition of a setup must be indicated by a red lamp “Setup switched on” and by a
green lamp “Setup switched off”.
If the fence is interrupted for assembly and dismantling operations on the setup, or during
large-scale modifications, all the prescribed precautions for entry to the setup shall be
observed. Here, particular attention must be paid to the reliable interruption of the main leads.
On isolating switches or other disconnecting points and on the control desk of the setup
concerned, warning boards inscribed “Do not switch on! Danger!” must be displayed.
Earthing
A high-voltage setup may be entered only when all the parts which can assume high-voltage
in the contact zone are earthed. Earthing may only be affected by a conductor earthed inside
the fence. Fixing the earthing leads onto the parts to be earthed should be done with the aid of
insulating rods. Earthing switches with a clearly visible operating position are also
permissible. In high-power setups with direct supply from the high-voltage network, earthing
is achieved by earthing isolators. Earthing may only follow switching the current source off
and may be removed only when there is no longer anyone present within the fence or if the
setup is vacated after removal of the earth. All metallic parts of the setup which do not carry
potential during normal service must be earthed reliably and with adequate cross-section of at
least 1.5 mn2 Cu. In test setups with direct supply from the high-voltage network, the earth
connections must be made with considerations of dynamic forces which can arise.
Circuit and Test setup
In the case that the setup is not supplied from ready wired desks, clearly marked isolating
switches must be provided in all leads to the low-voltages circuits of high-voltage
transformers and arranged at an easily identifiable position outside the fence. These must be
opened before earthing and before entering the setup.
All leads must be laid so that there are no loosely hanging ends. Low voltage leads which can
assume high potentials during breakdown or flashovers and lead out of the fenced area, e.g.
measuring cables, control cables and/or supply cables must be laid inside the setup in earthed
sleeves. All components of the setup must be either rigidly fixed or suspended so that they
cannot topple during operation or be pulled down by the leads. For all setups intended for
research purposes, a circuit diagram shall be fixed outside the fence in a clearly visible
position. A test setup may be put into operation only after the circuit has been checked and
permission to begin work given by an authorized person.
Conducting the experiments
Everyone carrying out experiments in the laboratory is personally responsible for the setup
placed at his disposal and for the experiments performed with it. For experiments during
working hours one should try, in the interest of personal safety, to make sure that a second
person is present in the testing room. If this is not possible, then at least at the times of the
beginning and ending of an experiment should be communicated to a second person. When
working with high voltages beyond working hours a second person familiar with the
experimental setups must be present in the same room.
If several persons are working with the same setup, they must all know who is to perform the
switching operations for a experiment. Before switching on high-voltage setups, warning
should be given either by short horn signals or by the call “Attention! Switching-on!” . This
is especially important during loud experiment can be announced when the equipment is de-
energized either by a single long tone or by the call “Switched off”.
Explosion and fire risk, radiation protection
In experiments with oil and other highly flammable materials, special care is necessary owing
to the danger of explosion and fire. In each room where work is carried out with these
materials, suitable fire extinguishers must be close to hand and ready for use. Highly
flammable waste products e.g. paper or used cotton waste, should always be disposed of
immediately in metal bins.
Accident insurance
Everyone working in the institute must be insured against accidents.
Conduct during accidents
Mode of action in case of an electrical accident:
1. Switch off the setup on all poles. So long as this has not been done, the victim of the
accident should not be touched under any circumstances.
2. If the victim is unconscious, notify the emergency service at once.

Telephone Number: ………………………………………………

3. Make immediate attempts to restore respiration by artificial respiration or chest
massage!
4. These measures must be continued, if necessary, up to the beginning of an operation.
(Only 6 to 8 minutes time before direct heart massage!).
5. Even during accidents with no unconsciousness, it is recommended that the victim
lies quietly, and a doctor’s advice is sought.
 Introduction to Control Desk
Description – Function of Controls
The Table over the next pages gives a summary of the control and operating devices of the
test equipment, as described in section 3.1, 3.2 and 3.3. Function of Controls refer to
Drg.no.387060 “Keyboard” and Drg.no.386557 “Case (S2, R1)”
Control Function Back Remarks
Signal
1. Toggle Switches on: The following The signals are
Switch Black -Mains voltage green lamps are
220V illuminated H5 H5: Primary
-Socket 220V (mounted in contactor OFF
S1 -Control Voltage S8)H5.1 H5.1:Primary
“ MAIN SWITCH” 24V (Lamps) on contactor OFF
-Control Voltage entrance of H7: Secondary
220V danger (zone) contactor OFF
-Auxiliary Voltage H7 (mounted in H9: Grounding
for measuring S10) H9 switch closed
instruments 220V
- Status “ Ready for
operation”
2. Push-button, Signal horn H1 As a warning for
black S3 sounds instance before
“HORN” high voltage is
applied
3. Key switch Switches off the Key prevents
S6 contactor control unauthorized
operation of
control.
ATTENTION:
Key can be
removed in either
positions
4. Emergency Switches off the Press button
OFF entire control catches when
Button S5 system – OFF operated. It is
EMERGENCY released spring
return.
5. Illuminated Primary voltage on Signal lamps
buttons regulating
5.1 OFF” S7 transformer
Green
- OFF H5, H5.1, H7,
H9
(refer to part.1)
5.2. “ON” S8 - On Red Everybody shall
- Status “ Ready for H4 (mounted in have left the
switching ON” S7) danger zone.
Red H4.1
(warning lamps The electrical
 (s) on entrance safety circuit
to danger zone) must be closed.
Red H8
grounding
switch open
6. Illuminated Buttons Secondary Voltage Signal Lamps
“SECONDARY” on regulating green
6.1 OFF” S9 transformer H7 (mounted in
-Primary voltage on S10)
test transformer.
- OFF
6.2. “ON” S10 - ON Red H6 The secondary
Status “Operating” (mounted in S9) voltage of the
and H4, H4.1 regulating
(refer to 5.2) transformer must
be on zero.
Otherwise
secondary
contactor cannot
be switched on.
For exceptions,
refer to par.10.
7. Toggle switches Setting primary
“ VOLATGE voltage on test
REGULATION” Transformer
7.1.“MAXIMUM” -With maximum
S15 (maximum speed) speed
7.2.”VARIABLE” - With variable
S14(variable speed) speed
Depending on
setting of R1 (refer
to par.8)
8. Potentiometer1 Setting of Regulating time
“REGULATING SPEED” regulating speed (0 to 100%) can
(refer to par.7) be set in the
range of
APPROX 30-120
seconds
9. Push button Reducing the 50% deflection Short time duty
Yellow S2 sensitivity of on Ammeter P2 10KVA for
“I x 2 max 2 min. 50%” current indication with same maximum 2 min.
and over current current.
tripping.
10. Push button Compulsory zero Application of
Yellow S11 reset is relinquished regulating
“UNLOCKING” transformer
secondary
voltage not reset
to is admissible
only up to 20%
 rated voltage and
shall be limited
to exceptional
cases.
11. Push Button, black S4 Switches off all For instance, to
“ LIGHT OFF” lamps as long as the allow
button is pressed. observation of
glow discharges.
12. Toggle switch S12 Increases ( + ) or The spheres of The control cable
“KF” (Sphere gap for reduces ( - ) the gap sphere gap KF between plug KF
impulse generator plant). setting of KF. are moved (X13) and drive
accordingly. AKF shall be
connected. AKF
and KF must be
inter connected
over the drive
shaft AS.
13. Toggle switch S13 Increases ( + ) or The spheres of The control cable
“MF” (Measuring reduces ( - ) the gap the measuring between plug MF
spark gap). setting of MF. spark gap MF (X14) and MF
are moved shall be
accordingly. connected.
 HV9159 Digital Oscilloscope
Technical specifications

The table below provides a summary of the main technical specifications of the HV9159
Digital oscilloscope. For further details please see the Rigol DS1052E Data Sheet.

Name Oscilloscope
Brand Rigol DS1052E
Bandwidth
Analog 50 MHz
Bandwidth
Acquisition
Sample Real-Time Sample Equivalent Sample
Modes
Sample Rate 1GSa/s 10GSa/s
Inputs
Input 1MN I 2%, 18pF 3Pf
Impedance
Maximum 400V
Input Voltage
Horizontal
Channel Mode Sample Rate Memory depth Memory Depth
(normal) (long memory)
Record length

Single channel 1GSa/s 16kpts N.A

Single channel 500MSa/s 16kpts 1Mpts

Dual channel 500MSa/s 8kpts N.A

Dual channel 250MSa/s 8kpts 512kpts

Scanning Sns/div-50s/div
Speed Range

Vertical
A/D 8-bit resolution, all channels sample simultaneously
Converter
Volts/div 2mV/div10V/div
Range
Single-shot 50MHZ
Bandwidth
 Trigger
Trigger 0.1div-1.Odiv (adjustable)
Sensitivity
Trigger Edge, Video, Pulse Width, Slope, Alternate
Modes
Math
Operations +, -, X, FFT, Invert
Display
Display Type 5.7inch. (145mm) diagonal TFT Liquid Crystal Display 64k color
Display 320 horizontal RGBX 234 vertical pixels
Resolution
Front panel and user interface

This section provides an overview of the most important controls to operate the
oscilloscope. For a more detailed look.

Front panel

The Multi-Function knob is used for a number of things, especially to scroll and select
settings in the submenus, adjusting the brightness and selecting/moving the measuring
cursors.

(1). The Common Menu buttons group consists of:

(a). The Measure button activates the automatic measurement function. The oscilloscopes
provide 20 auto measurements: Vpp, Vmax, Vmin, Vtop, Vbase, Vamp, Vavg, Vrms,
Overshoot, Preshoot, Freq, Period, Rise Time, Fall Time, Delay1-2, Delay1-2, +Width, -
Width, +Duty, -Duty.

(b).The Cursor button displays the menu for the different cursor measurement modes. The
cursor measurement has three modes: Manual, Track and Auto Measure.
(c).The Acquire button is used to set up the sampling system. Sampling modes, memory
depth and acquisition modes can be adjusted in the Acquire menu.

(d).The Display button activates the menu for the setting of the display system. Among other
things display type, intensity, brightness and grid settings can be adjusted.

(e).The storage button shows the menu for the settings of the storage system. Waveforms and
setup can be stored in and recalled from, both internal memory and external memory.

(f).Utility button is used for setting up the utility system. Such as IO settings, sound,
language, Printer settings and system information.

(2). Run Control Buttons include

(a). The AUTO button features automatic adjustments to produce a usable display of the
input signal.

(b). The RUN/STOP button starts and terminates the acquiring of a waveform.

(3). The Menu Selection buttons is used to make selections in the menus.

(4). The Vertical Control buttons group consist of:

(a). The CH1/CH2 buttons activates each channels operation menu. The type of
coupling,bandwidth limits, probe attenuation filters and scale resolution can be adjusted in
the operation menu.

(b). The Math button displays the menu for the oscilloscopes different mathematical

Operations. The mathematic functions include "add", "subtract”, “multiply" and

"FFT"

For Channel 1 and Channel 2.

(c). The REF button displays the reference waveform menu. Reference Waveforms are

Saved waveforms to be selected for display.

(d). The vertical Position knob is used to change the vertical display position of each channel.
Pressing the vertical Position knob moves the signal back to its original position in the middle
of the screen.

(e). The vertical Scale knobis used to change the vertical scale. Vertical Sensitivity is

2mV/div - 10V/div

(5). The horizontal control group includes

(a). The horizontal Position knob moves displayed signal horizontally. Pressing the knob
 sets the horizontal offset to its zero position.

(b). The horizontal Scale knob changes the sweep speed in a 1-2-5 step sequence, and

displays the value in the status bar. The time base ranges of the oscilloscope is from

Ins/div to 50s/div.

(6). The Trigger control group includes

(a). The Level knob sets the trigger level; press the knob and the level will reset to zero.

(b). The trigger MENU button activates the trigger controls menu where the type of mode,
source and sweep can be selected.

(c). The 50% button sets the trigger level to the vertical midpoint between the peaks of
thetrigger signal.

(d). The FORCE button is used to force create a trigger signal and the function is mainly
usedin Normal and Single mode.

(7). The USB Host is a USB interface used to save and load waveforms, setups, bitmaps and
CSV files.

(8). The Signal Input Channels are BNC connectors for channel 1 and 2.

(9). The EXT Trigger input is a BNC connector for an external trigger signal. External trigger
source uses the signal directly; it has a trigger level range of -1.2V to +1.2v.

(10). The Probe Compensation connector is used to match the characteristics of the probe and
the channel input. It has an amplitude of ~3Vp-p and a frequency of 1 kHz.

User interface
(1).The running status indicator shows the current status of the oscilloscope. The status may
be RUN, STOP, T' D, WAIT or AUTO.

(2). Trigger point shows the trigger point offset.

(3). The Trigger Level indicator shows the

trigger level, the trigger source and the current
trigger mode. The trigger level is adjusted with
the Level knob in Trigger Control group whilst the
source and mode is selected in the trigger
menu.

(4). The Trigger Offset indicator shows the

trigger offset, the trigger position will be changes
horizontally by turning the Position knob in the
Horizontal Control group.

(5). The Time/Div indicator shows the

horizontal time base it is adjusted by turning the horizontal Scale knob in the Horizontal
Control group.

(6). The Volt/Div indicator shows the vertical volts per division, the affected channel and the
type of coupling. The volt per division can be adjusted by turning the vertical Scale knob in
the vertical control group. The type of coupling, AC, DC or GND, can be selected under the
specific channels operational menu.

(7). The Channel indicator displays the number of the channel and is a indicator of the signals
value with respect to the ground reference located at the center of the screen. It can be moved
vertically by turning the vertical Position knob in the Vertical Control group.

(8). Vertical and Horizontal cursors are used to measure voltage and time respectively. The
positions of the cursors can be adjusted with the Multi-Function knob.
COLLEGE OF ENGINEERING & TECHNOLOGY
UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 1 Manual
Generation and Measurement of AC Voltage

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed

Marks obtained

Instructor Signature
CLO-1 To recognize the usage of control desk, testing
transformer, safety precautions and analytical system tool

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.

SAFETY PRECAUTIONS!!!
It is important and essential that all participants familiarize themselves and strictly follow all
safety precautions described in the Safety Regulations for High Voltage Experiments section
before commencing experiments.
Objective
Alternating voltages are required for most high-voltage tests. The investigations are performed
either directly with this type of voltage or used in circuits for the generation of high DC voltage
and impulse voltages. This experiment examines the generation of High AC Voltage using a
TERCO test transformer.
Reference
Terco HV 9150 Digital AC Voltmeter Manual.
Terco HV 9103 Control Desk Manual.
Equipment to be used
COMPONENT DESCRIPTION TERCO TYPE No. QUANTITY
HV Test Transformer HV9105 1

Control Desk HV9103 1

Measuring Capacitor HV9141 1

AC Peak Voltmeter HV9150 1

Connecting Rod HV9108 1

Connecting Cup HV9109 1

Floor pedestal HV9110 1

Earthing Rod HV9107 1

Test setup
The test setup consists of the transformer, a measuring capacitor, a connecting cup and a floor
pedestal, the electrical relationship of which is presented below:

Fig. 1.1 Circuit for AC Voltage measurement

Introduction
Setting up the HV experiment
High Voltage AC is generated in the Laboratory using the 220V/100kV Test Transformer
(HV9105). This is fed and controlled from the Control Desk. The high voltage experiments must
be carried out in dedicated HV experimental areas enclosed with metal barriers. Control desks
with power supply installations, safety circuits and the measuring instruments constitute the
standard equipment. For voltage measurement, one instrument for measuring the primary voltage
of the transformer and one AC peak voltmeter (HV9150) are provided at each desk. Participants
should study the circuit of the Control Desk (HV9103) and familiarize themselves with its
operation before commencing the experiment. This experiment assumes that power is supplied to
the control desk and the door contact has been connected.
Methods of Measuring High Alternating Voltages
High AC Voltages can be measured by different methods: Measurement of Urms using primary
input voltage and Transformer Ratio .Measurement of Û with the peak voltmeter (HV9150) via
an AC Measuring Capacitor (HV9141) .Determination by using the breakdown voltage Ûd of a
sphere gap .Determination of Û using a circuit after Chubb and Fortes cue. (Not covered here)
This experiment focuses on the first two methods of measurements, the results of which are then
used for comparison.
Transformer Ratio to calculate Urms from the transformer primary input voltage and the
transformer ratio, these values must first be established.
The HV 9103 Control Desk provides a user-regulated output voltage of 0 - 220/230 VAC. This is
fed to the primary side of the HV 9105 transformer.
 Fig. 1.2 Simplified Transformer Circuit
Uout is found by simply multiplying Uin by the transformer ratio:
Uout = 450 x Uin

Measuring Capacitor, The simplest and most common way of finding the AC voltage value in
the Terco HV setup is by way of a measuring capacitor. High-voltage capacitors are well-suited
for the reduction of high alternating voltages to values easily measurable with instruments.
Loading To keep loading on the voltage source as low as possible, the HV capacitor C1 should
be kept as small as possible. (In our case, 100pF for the HV 9141) Accuracy of high-voltage
measurement with capacitors is then limited only by the environment that can affect the
capacitor, C1. This is represented by the earth capacitance depicted as CE in circuit (a) below.

Fig. 1.3 (a) with Earth Capacitance (b) Equivalent Capacitance

The measuring circuit is connected at the low-voltage output terminal. For the current flowing
through the measuring circuit, which is determined by the primary capacitance C1, the earth
capacitance reduces the effective primary capacitance to:
4 CE
C=C 1 ≈ C(1− )
CE 4∗C 1
1+
4∗C1

Under the assumption of homogenous distribution of earth capacitance, it can be shown the CE is
equal to 2/3 of the total earth capacitance Ce acting at C1.
For cylindrical dividers, Ce can be calculated at a value of 12 - 20 pF/m in height.
The effect of change of capacitance must remain small to ensure adequate measuring accuracy.
This can be achieved in practice by making the high voltage capacitors static (always the same
Ce).
Experiment and procedure
Checking the Experimental Setup
The complete circuit diagram of the control desk and the current paths of the safety circuits
should be discussed and wherever possible, the actual wiring of the experimental setup traced. A
series of measures which guarantee protection against electrical accidents can be identified in the
circuit and the fulfillment of the safety regulations of Appendix-A should be determined using
the following methods.
Procedure
1. Ensure access to the specific manuals for the HV 9103 Control Desk and HV 9150 AC
voltmeter.
2. Check earth points. Always make sure there is a good quality earth connection, to which all
the components can be connected. This should be a high-quality busbar, situated inside the cage,
such as the one shown below.

Fig. 1.4 (a) Earthing Bushbar

If earthing plates are present, check all connections between them and connect directly to the
bushbar.
3. Make the transformer connections. Check that the 2 jumpers are present and connected as
indicated in the picture below.

Fig. 1.5 HV Transformer Connections

4. With the relevant connection cable, connect earth then the phases. The earthing connector
should be of an O-ring type to prevent accidental disconnections. Jumpers to ground plates earth
Bus-Bar and control desk.
5. Connect the transformer to the Control Desk. Insert the cable connector through the cable
opening and into the Regulated Voltage output at the rear of the Control Desk.
Note that this is a twist connector. The plug is inserted at the 10 o’clock position and twisted
clockwise to the 12 o’clock position to secure.

Fig. 1.6 (a) Control Desk Regulated Output Fig 2.7 regulated Voltage Connector

6. Position the Measuring Capacitor. First, a HV 9110 Floor Pedestal will be required. The
measuring capacitor will stand upright on this. Position the floor pedestal about 60cm from the
transformer where it will not cause an obstruction.
Note: The measuring capacitor should be positioned so that the signal output connector is at the
bottom (indicated by the blue ring, below).

Fig. 1.8 AC Voltage measurement Component Placement

7. Connect the capacitor to the transformer. Place a Connecting Cup on top of the upright
Measuring Capacitor, adjust the distance to the transformer and connect with a Connecting Rod.
Note: If no Earthing Plates are used, connect the measuring capacitor to the earth busbar.
8. Connect the Measuring Capacitor output to the Control Desk input. Connect the appropriate
coaxial cable from the Measuring Capacitor to the HV 9150 input, situated on the rear panel of
the Control desk.
 Fig. 1.9 HV 9150 AC Voltmeter Fig 2.10 AC
Note! how the excess cable has been hung up on the cage with quick ties to help protect the cable
and to prevent accidents inside the HV area.
9. Make sure the Control Desk has an earth connection to the busbar.
10. After double-checking all connections and ensuring good earthing for all relevant
components, the Control Desk can be connected to the power supply.
11. The rear of the Control desk should resemble the picture below, except for the cable hanging
to the left, which is the connection cable for the DC voltmeter. This is covered in future
experiments. Note the Door Contact connection at the bottom left (white cable).

Fig. 1.11 Control Desk connected and ready for AC voltage measurement

Note! On leaving the HV cage, place the HV 9107 earthing-rod across the door opening in a way
that anyone entering must first pick it up. This is good practice and very important for the
continued safety of participants as it serves as a reminder to discharge any components which
may hold a charge on entering the HV area.
12. Perform an Analysis. With the equipment ready to start, calculate the following expected AC
values using the transformer ratio method and enter the results in the results table.
13. Prepare for measurement. With the key, unlock the Control Desk and turn it on by the mains
switch.
14. At this point, make sure the AC voltmeter is set to the desired measurement position. Reset
using the reset button if required. (For more information, please see the dedicated HV 9150 AC
voltmeter manual.)
15. Begin measurement. Switch on the primary side by pressing the corresponding button (B).
Next, do the same for the secondary side (B).
16. Gradually increase the voltage using the controllers (C). At each primary voltage level in the
results table, record the displayed value.
17. Decrease the voltage back to zero.
18. Switch off the Control Desk.
Note! On entering the cage, always use the earthing rod to discharge any potential live power
sources

Fig. 1.12 Control Desk

Results
Results Table
Primary (regulated) Voltage Calculated Secondary Voltage Indicated Secondary Voltage

OBSERVATION:
 Assessment Rubric for Lab 1
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-1 To recognize the usage of control desk, testing transformer, safety precautions and
analytical system tool

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total
CLO-4 Write lab notes, effective communication and the design & analysis of the given
problem to perform in the laboratory environment as individual & team.

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)
Data and Professional Accurately Accurate Data are not
observations, looking and representation of representation of shown Or are
calculations and accurate the data in tables the data in written inaccurate. No or
analysis representation of and/or graphs. form, but no very poor
the data in tables Tables are tables are calculations are
and/or graphs. labelled and titled. presented. The done. The graphs
Tables are The calculations calculations are are not made. The
labelled and titled. are done with a done with a few relationship
The calculations few mistakes mistakes. between the
are done properly, and/or following Improper or no variables is not
following the the standard rules use of scientific discussed.
standard rules of of error notations, prefixes
error measurements and and units.
measurements and significant Analysis is made
significant figures. Scientific very poorly. The
figures. notations & relationship
Scientific prefixes are used between the
notations & and units are variables is
prefixes are used properly discussed but no
and units are mentioned. patterns, trends or
properly Analysis is made predictions are
mentioned. accurately. The made based on the
Analysis are made relationship data.
neatly and between the
accurately. The variables is
relationship discussed and
between the trends/patterns
variables is logically
discussed and analyzed.
trends/patterns
logically
analyzed.
 Total

COLLEGE OF ENGINEERING & TECHNOLOGY

UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 2 Manual
Generation and Measurement of AC Voltage through Oscilloscope.

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed
 Marks obtained

Instructor Signature

CLO-1 To recognize the usage of control desk, testing

transformer, safety precautions and analytical system tool

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.

SAFETY PRECAUTIONS!!!
It is important and essential that all participants familiarize themselves and strictly follow all
safety precautions described in the Safety Regulations for High Voltage Experiments section
before commencing experiments.
Objective
Alternating voltages are required for most high-voltage tests. The investigations are performed
either directly with this type of voltage or used in circuits for the generation of high DC voltage
and impulse voltages. This experiment examines the generation of High AC Voltage using a
TERCO test transformer.
Reference
Terco HV 9150 Digital AC Voltmeter Manual.
Terco HV 9103 Control Desk Manual.
Equipment to be used
COMPONENT DESCRIPTION TERCO TYPE No. QUANTITY
HV Test Transformer HV9105 1

Control Desk HV9103 1

Measuring Capacitor HV9141 1

AC Peak Voltmeter HV9150 1

Connecting Rod HV9108 1

Connecting Cup HV9109 1

Floor pedestal HV9110 1

Oscilloscope HV9159 1

Earthing Rod HV9107 1

High voltage measurement

AC measurement

Test setup

Fig. 2.1 Circuit for AC Voltage measurement

This experiment assumes that power is supplied to the control desk and the door contact has been
connected. High Voltage AC is generated in the Laboratory using the 220V/100kV Test
Transformer (HV9105). This is fed and controlled from the Control Desk. For voltage
measurement, one instrument for measuring the primary voltage of the transformer and one AC
peak voltmeter HV9150 are provided at each desk. Connect the appropriate coaxial cable
between the HV9141 measuring capacitor output and the X17 HV9150 capacitor divider input
on the back of the HV9103 Control desk.

Connect the the 10:1 probe between the X27 peak voltmeter output on the front of the control
des and the channel 1 input of the HV9159 oscilloscope.

Fig. 2.2 Oscilloscope connection

After double-checking all connections and earthing, ensure that everybody has exited the HV
cage. Then proceed with switching on the control desk and increase the alternating voltage to
100 kV Ú/v2.

Voltage dividers : The HV9141 measuring capacitor together with the HV9150 makes a voltage
divider. The HV9141 has a capacitance of 100 pF and the HV9150 set in the one stage position
has a capacitance of 200 nF making the voltage divider roughly 2000:1
 Fig. 2.3 Voltage divider connection
Oscilloscope settings

There are two ways to make the accurate settings for a AC measurement on the HV9159

oscilloscope. The correct settings can either be loaded from the internal/external memory on
configured manually. The table below provides a
summary of the oscilloscope settings for
measuring AC voltage.

Vertical Controls
Probe attenuation 10x
Scale 25V
Position 0V
Trigger Controls
Mode Edge
Source CH1
Sweep Auto
Measure
Source CH1
Voltage V max , V rms
Time Frequency
Horizontal Controls
Scale 5ms
Position 0
Curser setup
Mode Auto

Oscilloscope setting
There are two ways to make the correct settings for a DC
measurement on the HV 9159 oscilloscope. The accurate setting can either be loaded from
external/internal memory or configured manually. The table below provides a summary of the
oscilloscope setting for measuring a AC voltage
Manual setup
Press the CH1 button under the vertical control group. Turn the position knob until the channel 1
signal indicator is at the 0V position (signal in the middle of screen). Turn the scale knob to until
the volt per division indicator states 20mV

Fig. 2.4 Vertical control setting

Under the probe menu select 10X to match the attenuation factor of the probe. To adjust the
vertical scaling go to the second menu and select fine under the Volts/Div label or press the
vertical scale knob. Turn the vertical scale knob to adjust the volts per division to 300mV

Fig. 2.5 Attenuation factor of probe

Turn the scale knob in the Horizontal controls group until the time per division indicator states 5
ms

Fig. 2.6 Horizontal Control

Press the menu button in the trigger control group to activate the trigger control menu
 Fig. 2.7 Trigger Control

Select Edge under the Model label to trigger on rising edge. Select CH1 as the trigger signal
under the source label. Finally press the trigger sweep label and select auto

Fig. 2.8 Trigger sweep label

Under the common buttons group press the Measure Button to display the menu for the settings
of Automatic Measurements

Fig. 2.9 Measurement Setting

First press the Source label to make sure that CH1 is selected source channel. Then press the
Time Label and select the Freq. finally select vpp located in the voltage menu.

Fig. 2.10 Source Channel Setting

Press the Cursor setup button in the Common Menu buttons group and make sure that the Auto
Measure mode is selected.

Fig. 2.11 Cursor Setup Button

Results
Results Table
Primary (regulated) Voltage Calculated Secondary Voltage Indicated Secondary Voltage
OBSERVATION/DISCUSSION:
 Assessment Rubric for Lab 2
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-1 To recognize the usage of control desk, testing transformer, safety precautions and
analytical system tool

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total
CLO-4 Write lab notes, effective communication and the design & analysis of the given
problem to perform in the laboratory environment as individual & team.

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)
Data and Professional Accurately Accurate Data are not
observations, looking and representation of representation of shown Or are
calculations and accurate the data in tables the data in written inaccurate. No or
analysis representation of and/or graphs. form, but no very poor
the data in tables Tables are tables are calculations are
and/or graphs. labelled and titled. presented. The done. The graphs
Tables are The calculations calculations are are not made. The
labelled and titled. are done with a done with a few relationship
The calculations few mistakes mistakes. between the
are done properly, and/or following Improper or no variables is not
following the the standard rules use of scientific discussed.
standard rules of of error notations, prefixes
error measurements and and units.
measurements and significant Analysis is made
significant figures. Scientific very poorly. The
figures. notations & relationship
Scientific prefixes are used between the
notations & and units are variables is
prefixes are used properly discussed but no
and units are mentioned. patterns, trends or
properly Analysis is made predictions are
mentioned. accurately. The made based on the
Analysis are made relationship data.
neatly and between the
accurately. The variables is
relationship discussed and
between the trends/patterns
variables is logically
discussed and analyzed.
trends/patterns
logically
analyzed.
 Total

COLLEGE OF ENGINEERING & TECHNOLOGY

UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 3 Manual
Generation and Measurement of AC Voltage through Sphere Gaps.

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed

Marks obtained
 Instructor Signature

CLO-1 To recognize the usage of control desk, testing

transformer, safety precautions and analytical system tool

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.

SAFETY PRECAUTIONS!!!
It is important and essential that all participants familiarize themselves and strictly follow
all safety precautions described in the Safety Regulations for High Voltage Experiments
section before commencing experiments
Objective
To further investigate the generation of High AC Voltage using a Terco test transformer and
measurement of such by way of a Measuring Sphere Gap.
Reference
Terco HV 9150 Digital AC Voltmeter Manual
Terco HV 9103 Control Desk Manual
Terco HV 9133 Measuring Sphere Gap Manual

Equipment to be used

COMPONENT DESCRIPTION TERCO TYPE No. QUANTITY

HV Test Transformer HV9105 1

Control Desk HV9103 1

Measuring Capacitor HV9141 1

AC Peak Voltmeter HV9150 1

Measuring Sphere Gap HV9133 1

Connecting Rod HV9108 2

Charging Resistor HV9121 1

Connecting Cup HV9109 2

Floor pedestal HV9110 1

Earthing Rod HV9107 1

Test setup
The test setup builds on the previous setup with the addition of the HV 9121 Charging Resistor
and the HV 9133 Measuring Sphere Gap. Two connecting cups are required.

Fig. 3.1 Circuit for Sphere Gap AC Voltage Measurement via Control Desk
Instrumentation

Introduction
Setting up the HV experiment
The high-voltage experiments must be carried out in dedicated HV experimental areas,
enclosed with metal barriers.

Methods of Measuring High Alternating Voltages

High Alternating Voltages can be measured by different methods:
• Measurement of Urms using primary input voltage and Transformer Ratio
• Measurement of Û with the peak voltmeter (HV9150) in conjunction with AC
Measuring Capacitor (HV9141)
• Determination by using the breakdown voltage Ûd of a sphere gap;
• Determination of Û using a circuit after Chubb and Fortescue.

This experiment utilizes the Terco HV 9133 Measuring Sphere Gap to determine the
breakdown voltage.

Breakdown Voltage Ûd of a Sphere Gap

At high voltage, almost anything can become a conductor of electricity - even air. Proof of this
is seen in an everyday lightning strike. The point at which a gas or material stops being as
insulator and becomes conductive is known as its ‘Dielectric Breakdown’ point.

The voltage which must be applied for dielectric breakdown to occur is referred to as
‘Breakdown Voltage’.
Paschen’s Law
Paschen's law describes how the breakdown voltage of a spark gap depends on electrode
separation and the pressure of the surrounding gas.
It states that the voltage required to spark a specific gas is constant, if the same is true for the
product of pressure and separation.

Breakdown voltage in a gas:

a( pd )
V=
ln ( pd )+ b

• V is the breakdown voltage in volts

• p is the pressure in atmospheres
• d is the gap distance in meters

The constants a and b depend upon the composition of the gas. For air at standard atmospheric
pressure, a = 43600000 and b = 12.8.

This relationship breaks down completely at low pressures and very short distances (less than
5.7mm).
Procedure
This experiment assumes the transformer and control desk have been connected and tested in
accordance with the previous experiment.

1. Ensure access to the specific manuals for the HV 9103 Control Desk, HV 9150 AC
voltmeter and HV 9133 Measuring spark Gap for reference.

2. Check earth points. Always make sure there is a good quality earth connection, to which all
the components can be connected. This should be a high-quality busbar, situated inside the
cage, such as the one shown below.

Fig. 3.2 Earthing Busbar

If earthing plates are present, check all connections between them and connect directly to
the busbar.
3. Ensure the transformer is connected correctly to the control desk. For instructions on how
to do this, see previous experiment.

4. Stand the HV 9141 Measuring Capacitor on a Floor Pedestal and position a Connecting
Cup on top as in Experiment 1A.

Fig. 3.3 Setup Step 1

5. Connect the Measuring Capacitor to the Control desk. (See preceding experiment)

6. Place the HV 9121 Charging Resistor between the transformer and the Measuring
Capacitor.

Fig. 3.4 Setup Step 2

7. Now position the Measuring Sphere Gap. This will be connected via the Connecting Cup
on top of the Measuring Capacitor by a HV 9108 Connecting Rod so the distance should
reflect this. (For more information on the Measuring Sphere gap, please see the dedicated
manual).
 Connecting
Cup here.

Fig 3.5 Setup step 3

8. Place a Connecting Cup on the top of the Measuring Sphere Gap and connect to the
Measuring Capacitor with a HV 9108 Connecting Rod.

Note! The Measuring Sphere Gap requires individual earthing.

9. Connect a suitable earth cable, with o-ring type connector, to the Earth Point near the base
of the HV 9133. Fasten the other end securely to the Earthing Busbar.
 Fig. 3.6 Sphere gap Earth Connection point to bushbar

10. With the cable provided, connect the HV 9133 Measuring Sphere Gap to the HV 9133
Motor Control Input at the rear of the Control desk.

Fig 3.7 HV 9133 Sphere Gap Motor Control Input

11. After double-checking all connections and earthing, ensure that everybody has exited the
HV cage. On exiting, the last person should position the HV 9107 Earthing Rod across the
entrance before closing and locking the gate.

12. Switch on the Control Desk. Note the status of the warning lights above the gate. Answer
questions 1, 2 and 3 in the Questions section.

13. Adjust the sphere gap to the desired distance using the controller switches indicated by the
red ring, Fig 2.9 below.
 Fig. 3.8 Sphere Gap Adjustment Switches

14. Make sure the AC voltmeter is set to measure peak voltage, reset if necessary.

15. Sound the horn to warn others that loud noises may occur. (Blue ring, Fig 2.9)

16. Increase the voltage slowly and record the breakdown voltage indicated on the AC peak
voltmeter for each distance in the results table. Repeat each distance a few times for
improved accuracy.

17. Once the breakdown occurs, decrease the voltage until the spark is extinguished.

18. Cause a breakdown once again but this time, instead of decreasing the voltage, increase the
gap. Answer question 5 in the Questions section.
Results
Results table
Sphere Gap Distance Theoretical Breakdown Observed Breakdown
(mm) Voltage (kV) Voltage (kV)
10
20
30
40
50
60

OBSERVATION/DISCUSSION:
 Assessment Rubric for Lab 3
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-1 To recognize the usage of control desk, testing transformer, safety precautions and
analytical system tool

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total
CLO-4 Write lab notes, effective communication and the design & analysis of the given
problem to perform in the laboratory environment as individual & team.

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)
Data and Professional Accurately Accurate Data are not
observations, looking and representation of representation of shown Or are
calculations and accurate the data in tables the data in written inaccurate. No or
analysis representation of and/or graphs. form, but no very poor
the data in tables Tables are tables are calculations are
and/or graphs. labelled and titled. presented. The done. The graphs
Tables are The calculations calculations are are not made. The
labelled and titled. are done with a done with a few relationship
The calculations few mistakes mistakes. between the
are done properly, and/or following Improper or no variables is not
following the the standard rules use of scientific discussed.
standard rules of of error notations, prefixes
error measurements and and units.
measurements and significant Analysis is made
significant figures. Scientific very poorly. The
figures. notations & relationship
Scientific prefixes are used between the
notations & and units are variables is
prefixes are used properly discussed but no
and units are mentioned. patterns, trends or
properly Analysis is made predictions are
mentioned. accurately. The made based on the
Analysis are made relationship data.
neatly and between the
accurately. The variables is
relationship discussed and
between the trends/patterns
variables is logically
discussed and analyzed.
trends/patterns
logically
analyzed.
 Total

COLLEGE OF ENGINEERING & TECHNOLOGY

UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 4 Manual
Generation and measurement of DC voltage

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed

Marks obtained
 Instructor Signature

CLO-1 To recognize the usage of control desk, testing

transformer, safety precautions and analytical system tool

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.

SAFETY PRECAUTIONS!!!
It is important and essential that all participants familiarize themselves and strictly follow
all safety precautions described in the Safety Regulations for High Voltage Experiments
section before commencing experiments
Objective
The objective of this experiment is to investigate high voltage generation and measurement using
Terco HV equipment. The knowledge gained is s prerequisite for performing following
experiments.
Note: Extra care is essential in direct voltage experiments, since the high-voltage capacitors in
many circuits retain their full voltage, for a long time even after disconnection. Earthing
regulations are to be strictly observed. Even unused capacitors can acquire dangerous charges!
Reference
Terco HV 9103Control Desk Manual
Terco HV 9150 Digital AC Voltmeter Manual
Terco HV 9151 Digital DC Voltmeter Manual
Equipment to be use
COMPONENT DESCRIPTION TERCO TYPE No. QUANTITY
HV Test Transformer HV9105 1
Control Desk HV9103 1
Measuring Capacitor HV9141 1
Rectifier HV9111 2
Smoothing capacitor HV9112 2
Measuring Resistor HV9113 1
Insulating Rod HV9124 1
Connecting Rod HV9108 3
Connecting cup HV9109 5
Floor Pedestal HV9110 5
Spacer Bar HV9119 4
Electrode HV9138 1
Earthing Switch HV9120 1
Earthing Rod HV9107 1
DC Voltmeter HV9151 1
Resistor HV9121 1
 Load Capacitor HV9127 1

Test setup

Fig 4.1 Test setup

Recommended external equipment
None
Introduction
Generation of High Direct Voltages
High direct voltages required for testing purposes are mostly produced from high alternating
voltages by rectification and wherever necessary, subsequent multiplication. Multiplication can
be performed by way of a Greinacher Doubler Circuit which is outside the scope of this
Beginners Experiments manual but discussed further in the High Voltage Experiments manual.
In this setup, the alternating high voltage is rectified with 2 HV 9111 rectifiers, placed in series.
The HV 9112 capacitor then smoothes the half-wave rectified voltage. Atop the smoothing
capacitor, an electrode is placed to provide a good contact surface for the HV 9114 Grounding
Switch. The Grounding Switch contacts the electrode on loss of supply current to the
transformer, subsequently discharging the capacitor. This can occur when the transformer supply
current is switched off via the control panel or if the HV cage door is opened while an
experiment is in progress.
Note! Because of the potentially lethal voltages involved, the HV 9107 earthing rod should
always be used when entering the HV area.
The smoothed direct voltage is measured by voltage division in the HV9113 measuring resistor
and the value displayed on the HV9151 DC voltmeter, situated on the front panel of the HV 9103
control desk.
Procedure
1. To use space more efficiently, the setup can be built in an ‘L’ shape as seen below. The
alternating voltage measurement setup in the left of the picture is positioned at a 90-degree angle
to the rectification step, which is built to the right.

Fig 4.2 Direct Voltage Measurement Setup

Note: If earth-plates such as those above are not present, make sure each component is
sufficiently grounded by a suitable cable with O-ring connectors to prevent accidental
disconnection.
2. Start by building the alternating current setup from Experiment 1.

Fig 4.3 AC Voltage Measurement Setup

2. Next position 3 floor pedestals in a line as seen in Fig 3.2, above.
3. Place the Positioning Ring of the HV 9114 Earthing Switch over the second-floor pedestal.
The Smoothing Capacitor will then hold this in place when mounted.
4. Erect the HV 9124 Isolator first and place a Connecting Cup on top.
5. Secure the first section in place by adding the first HV 9111 Rectifier. It is good practice to
continue constructing each section until it is secure before moving on to the next. This prevents
any components being damaged from being accidentally knocked over.
 Fig 4.4Rectifier and Isolator secured
Note! Do not pick up the capacitor by the ends as a substantial charge may have accumulated
while at rest. It is good practice to always discharge a capacitor before handling it. This is done
easily by short-circuiting the ends with any electrical laboratory cable.
6. Resist picking the HV 9112 smoothing capacitor up by the ends, maneuver the bottom
connector through the Earthing-Switch Positioning-Ring and into the Floor Pedestal.
7. Place the HV 9138 Electrode atop the capacitor, making sure not to trap the Earthing Switch
Rod underneath (the rod should be able to drop away without hindrance).

Fig 4.5 Rectifier and Smoothing Capacitor Section

8. Add the Connecting Cup and position the second rectifier to secure the section.
9. Construct the next section including the HV 9113 Measuring Resistor, a Connecting Rod,
Floor Pedestal and Connecting Cup.
Note! Ensure the signal output connector is closest to the floor as indicated below. Failure to do
so will result in high voltage being sent directly into the Control Panel.
 Fig 4.6 Measuring Resistor Orientation
10. Double-check all connections and exit the cage, leaving the Earthing Rod positioned across
the doorway, as usual.
11. Switch on the Control Desk. Make sure the regulated voltage is at minimum before applying
any power to the transformer.
12. Reset the AC voltmeter if desired; check that the correct stage level is set on both
instruments.
Note: Before starting the experiment, sound the warning horn to inform people close by that an
experiment is in progress and sudden loud noises can occur.
Fig 4.7 Control Desk
13. Answer questions 1 and 2 in the Questions section.
14. After sounding the horn, power may be provided to the transformer primary and secondary
sides.
15. At several levels, note the measured AC voltage levels and calculate the expected DC voltage
level. Compare with the rectified DC voltage level displayed. Note! Before switching off the
transformer from the Control Desk, remember to decrease the regulated voltage down to zero.
Note: On entering the HV cage be sure to use the earthing rod to discharge any possible sources
of remaining voltage.

Results
Results Table

Alternating voltage peak Theoretical Direct Voltage Displayed Direct Voltage

(kV) (kV) (kV)

OBSERVATION/DISCUSSION:
 Assessment Rubric for Lab 4
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-1 To recognize the usage of control desk, testing transformer, safety precautions and
analytical system tool

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total
CLO-4 Write lab notes, effective communication and the design & analysis of the given
problem to perform in the laboratory environment as individual & team.

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)
Data and Professional Accurately Accurate Data are not
observations, looking and representation of representation of shown Or are
calculations and accurate the data in tables the data in written inaccurate. No or
analysis representation of and/or graphs. form, but no very poor
the data in tables Tables are tables are calculations are
and/or graphs. labelled and titled. presented. The done. The graphs
Tables are The calculations calculations are are not made. The
labelled and titled. are done with a done with a few relationship
The calculations few mistakes mistakes. between the
are done properly, and/or following Improper or no variables is not
following the the standard rules use of scientific discussed.
standard rules of of error notations, prefixes
error measurements and and units.
measurements and significant Analysis is made
significant figures. Scientific very poorly. The
figures. notations & relationship
Scientific prefixes are used between the
notations & and units are variables is
prefixes are used properly discussed but no
and units are mentioned. patterns, trends or
properly Analysis is made predictions are
mentioned. accurately. The made based on the
Analysis are made relationship data.
neatly and between the
accurately. The variables is
relationship discussed and
between the trends/patterns
variables is logically
discussed and analyzed.
trends/patterns
logically
analyzed.
 Total

COLLEGE OF ENGINEERING & TECHNOLOGY

UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 5 Manual
Generation and measurement of DC voltage through oscilloscope

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed

Marks obtained
 Instructor Signature

CLO-2 Assemble and examine High voltage, impulse voltage

generation and measurement of performance

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.

SAFETY PRECAUTIONS!!!
It is important and essential that all participants familiarize themselves and strictly follow
all safety precautions described in the Safety Regulations for High Voltage Experiments
section before commencing experiments
Objective
The objective of this experiment is to investigate high voltage generation and measurement using
Terco HV equipment. The knowledge gained is s prerequisite for performing following
experiments.
Note: Extra care is essential in direct voltage experiments, since the high-voltage capacitors in
many circuits retain their full voltage, for a long time even after disconnection. Earthing
regulations are to be strictly observed. Even unused capacitors can acquire dangerous charges!
Reference
Terco HV 9103Control Desk Manual
Terco HV 9150 Digital AC Voltmeter Manual
Terco HV 9151 Digital DC Voltmeter Manual
Equipment to be use
COMPONENT
TERCO TYPE No. QUANTITY
DESCRIPTION
HV Test Transformer HV9105 1
Control Desk HV9103 1
Measuring Capacitor HV9141 1
Rectifier HV9111 2
Smoothing capacitor HV9112 2
Measuring Resistor HV9113 1
Insulating Rod HV9124 1
Connecting Rod HV9108 3
Connecting cup HV9109 5
Floor Pedestal HV9110 5
Spacer Bar HV9119 4
Electrode HV9138 1
Earthing Switch HV9120 1
Earthing Rod HV9107 1
DC Voltmeter HV9151 1
 Resistor HV9121 1
Oscilloscope HV9159 1
Load Capacitor HV9127 1

DC measurement
Test setup

Fig 5.1 Test setup

This experiment assumes that power is supplied to control desk and the door contact has been
connected. High voltage AC is generated in the laboratory using the 220KV/100KV test
transformer (HV9105). This is fed and controlled from control desk. In this setup, the alternating
high voltage is rectified with two HV9111 rectifiers placed in the series. The HV 9112 capacitor
then smoothen the rectified DC voltage. For the voltage measurement, one instrument for
measuring the primary voltage of transformer, one AC peak voltmeter HV 9150 and a DC
voltmeter HV9151 are provided at each desk. Connect the appropriate coaxial cable from the
measuring capacitor HV9141 to the X17 HV9150 input and the measuring resistor HV 9113 to
the X21 HV 9151 input, situated on the rear panel of the control desk. On the top of smoothing
capacitor an electrode is placed that provide a good contact surface for the HV 9114 grounding
switch. The HV 9114 grounding switch is then connected to the control desk.
Connect the 10.1 probe between the X27 peak voltmeter output on the front of control desk and
the channel 1 input of HV 9159 oscilloscope

After double checking all connections and earthing, ensure that everybody has exited the HV
cage. Then proceed with switching on the control desk and increase the alternating voltage to
32150KV.
Oscilloscope setting
There are two ways to make the correct settings for a DC measurement on the HV 9159
oscilloscope. The accurate setting can either be loaded from external/internal memory or
configured manually. The table below provides a summary of the oscilloscope setting for
measuring a DC voltage.

Fig 5.2 Oscilloscope setting

Manual setup
Press the CH1 button under the vertical control group. Turn the position knob until the channel 1
signal indicator is at the 0V position (signal in the middle of screen). Turn the scale knob to until
the volt per division indicator states 20mV

Fig 5.3 vertical controls

Under the probe menu select 10X to match the attenuation factor of the probe. To adjust the
vertical scaling go to the second menu and select fine under the Volts/Div label or press the
vertical scale knob. Turn the vertical scale knob to adjust the volts per division to 300mV

Fig 5.4 Attenuation factor of probe

Turn the scale knob in the Horizontal controls group until the time per division indicator states 5
ms

Fig 5.5 horizontal controls

Press the menu button in the trigger control group to activate the trigger control menu

Fig 5.6 Tigger control

Select Edge under the Model label to trigger on rising edge. Select CH1 as the trigger signal
under the source label. Finally press the trigger sweep label and select auto

Fig 5.7 Trigger sweep label

Under the common buttons group press the Measure Button to display the menu for the settings
of Automatic Measurements

Fig 5.8 Measurement controls

First press the Source label to make sure that CH1 is selected source channel. Then press the
Time Label and select the Freq. finally select Vp-p located in the voltage menu.

Fig 5.9
Press the Cursor setup button in the Common Menu buttons group and make sure that the Auto
Measure mode is selected.

Fig 5.10 Cursor setting

Results

Results Table

Alternating voltage peak Theoretical Direct Voltage Displayed Direct Voltage

(kV) (kV) (kV)
OBSERVATION/DISCUSSION:
 Assessment Rubric for Lab 5
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-2 Assemble and examine High voltage, impulse voltage generation and measurement
of performance

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total
CLO-4 Write lab notes, effective communication and the design & analysis of the given
problem to perform in the laboratory environment as individual & team.

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)
Data and Professional Accurately Accurate Data are not
observations, looking and representation of representation of shown Or are
calculations and accurate the data in tables the data in written inaccurate. No or
analysis representation of and/or graphs. form, but no very poor
the data in tables Tables are tables are calculations are
and/or graphs. labelled and titled. presented. The done. The graphs
Tables are The calculations calculations are are not made. The
labelled and titled. are done with a done with a few relationship
The calculations few mistakes mistakes. between the
are done properly, and/or following Improper or no variables is not
following the the standard rules use of scientific discussed.
standard rules of of error notations, prefixes
error measurements and and units.
measurements and significant Analysis is made
significant figures. Scientific very poorly. The
figures. notations & relationship
Scientific prefixes are used between the
notations & and units are variables is
prefixes are used properly discussed but no
and units are mentioned. patterns, trends or
properly Analysis is made predictions are
mentioned. accurately. The made based on the
Analysis are made relationship data.
neatly and between the
accurately. The variables is
relationship discussed and
between the trends/patterns
variables is logically
discussed and analyzed.
trends/patterns
logically
analyzed.
 Total

COLLEGE OF ENGINEERING & TECHNOLOGY

UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 6 Manual
Voltage Doubler Circuit.

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed

Marks obtained
 Instructor Signature

CLO-2 Assemble and examine High voltage, impulse voltage

generation and measurement of performance

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.
SAFETY PRECAUTIONS!!!
It is important and essential that all participants familiarize themselves and strictly follow
all safety precautions described in the Safety Regulations for High Voltage Experiments
section before commencing experiments
Objective
High direct voltages are necessary for testing insulation systems, for charging capacitive storage
devices and for many other applications in physics and technology. The topic covered in this
experiment is:
I) Greinacher Voltage doubler-circuit
Note: Extra care is essential in direct voltage experiments, since the high-voltage capacitors in
many circuits retain their full voltage, for a long time even after disconnection. Earthing
regulations are to be strictly observed. Even unused capacitors can acquire dangerous charges!
Reference
See Appendix 1- Experiment 3
Equipment to be used

COMPONENT
TERCO TYPE No. QUANTITY
DESCRIPTION
HV Test Transformer HV9105 1
Control Desk HV9103 1
Rectifier HV9111 2
Smoothing capacitor HV9112 2
Measuring Resistor HV9113 1
Measuring Sphere-gap HV9133 1
Connecting Rod HV9108 1
Connecting cup HV9109 4
Floor Pedestal HV9110 3
Spacer Bar HV9119 3
Electrode HV9138 1
Earthing Switch HV9114 1
Earthing Rod HV9107 1
 DC Voltmeter HV9151 1
Load Resistor 2.5 M Ohms HV9127 1

Test setup

Fig. 6.1 Experimental Setup of Greinacher Doubler Circuit

Recommended external equipment

I) General Purpose Digital Storage Oscilloscope
 Fig. 6.2 Circuit diagram and voltage curves in a Greinacher doubler-circuit
a) Circuit diagram, b) voltage curves for C1 = C2
Introduction
Greinacher Doubler-Circuit

The circuit in Fig. 6.1 should be set up. The variation in potential at point b with respect to earth
is to be recorded. The amplitude of the direct voltage at b, as well as the primary voltage of the
transformer, should also be measured.
The relationship between breakdown voltage and spacing shown in Fig. 6.4 was obtained for this
experiment. One can see that for larger spacings and a positive point electrode, the excess
positive ions in the field region lead to a lower breakdown voltage.

OBSERVATION/DISCUSSION:
 Assessment Rubric for Lab 6
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-2 Assemble and examine High voltage, impulse voltage generation and measurement
of performance

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total
CLO-4 Write lab notes, effective communication and the design & analysis of the given
problem to perform in the laboratory environment as individual & team.

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)
Data and Professional Accurately Accurate Data are not
observations, looking and representation of representation of shown Or are
calculations and accurate the data in tables the data in written inaccurate. No or
analysis representation of and/or graphs. form, but no very poor
the data in tables Tables are tables are calculations are
and/or graphs. labelled and titled. presented. The done. The graphs
Tables are The calculations calculations are are not made. The
labelled and titled. are done with a done with a few relationship
The calculations few mistakes mistakes. between the
are done properly, and/or following Improper or no variables is not
following the the standard rules use of scientific discussed.
standard rules of of error notations, prefixes
error measurements and and units.
measurements and significant Analysis is made
significant figures. Scientific very poorly. The
figures. notations & relationship
Scientific prefixes are used between the
notations & and units are variables is
prefixes are used properly discussed but no
and units are mentioned. patterns, trends or
properly Analysis is made predictions are
mentioned. accurately. The made based on the
Analysis are made relationship data.
neatly and between the
accurately. The variables is
relationship discussed and
between the trends/patterns
variables is logically
discussed and analyzed.
trends/patterns
logically
analyzed.
 Total

COLLEGE OF ENGINEERING & TECHNOLOGY

UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 7 Manual
Polarity Effect and Insulation Screen.

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed

Marks obtained
 Instructor Signature

CLO-2 Assemble and examine High voltage, impulse voltage

generation and measurement of performance

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.

SAFETY PRECAUTIONS!!!
It is important and essential that all participants familiarize themselves and strictly follow
all safety precautions described in the Safety Regulations for High Voltage Experiments
section before commencing experiments
Objective
High direct voltages are necessary for testing insulation systems, for charging capacitive storage
devices and for many other applications in physics and technology. The topics covered in this
experiment are:
I) Polarity effect,
II) Effect of insulating screens.

Equipment to be used

COMPONENT
TERCO TYPE No. QUANTITY
DESCRIPTION
HV Test Transformer HV9105 1
Control Desk HV9103 1
Rectifier HV9111 2
Smoothing capacitor HV9112 2
Measuring Resistor HV9113 1
Measuring Sphere-gap HV9133 1
Connecting Rod HV9108 1
Connecting cup HV9109 4
Floor Pedestal HV9110 3
Spacer Bar HV9119 3
Electrode HV9138 1
 Earthing Switch HV9114 1
Earthing Rod HV9107 1
DC Voltmeter HV9151 1
Load Resistor 2.5 M Ohms HV9127 1

Test setup

Fig. 7.1 Test Setup

Introduction
Polarity Effect in a Point-Plane Gap
At an electrode with strong curvature in air, collision ionization results when the onset voltage is
exceeded. On account of their high mobility, the electrons rapidly leave the ionizing region of
the electric field. The slower ions build up a positive space charge in front of the point electrode
and change the potential distribution as shown in Fig. 6.2.
When the point electrode is negative, the electrons move towards the plate. The remaining ions
cause very high field strengths immediately at the tip of the point electrode, whereas the rest of
the field region shows only slight potential differences. This prevents the growth of discharge
channels in the direction of the plate.
For a positive point electrode, the electrons move towards it and the remaining ions reduce the
field strength immediately in front of the point electrode. Hence, since the field strength in the
direction of the plate then increases, this favors the growth of discharge channels.
 Fig. 7.2
Polarity Effect
A point-plane gap, in series with a 10 kΩ protective resistance, is connected in parallel to the
measuring resistance HV9113 in the circuit of Fig. 6.1. The breakdown voltage of this spark gap
should be measured for both polarities, at spacing s = 10, 20, 30, 40, 60 and 80 mm. The
transformer voltage may not be increased beyond 50 kV in this experiment, to avoid overloading
of the rectifiers and capacitors.

Fig. 7.3 Polarity effect in a point plane Gap

The relationship between breakdown voltage and spacing shown in Fig. 6.3 was obtained for this
experiment. One can see that for larger spacing and a positive point electrode, the excess positive
ions in the field region lead to a lower breakdown voltage.
 Distance Positive Polarity Distance Negative Polarity
mm Voltage mm Voltage

OBSERVATION:
 Assessment Rubric for Lab 7
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-2 Assemble and examine High voltage, impulse voltage generation and measurement
of performance

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total
CLO-4 Write lab notes, effective communication and the design & analysis of the given
problem to perform in the laboratory environment as individual & team.

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)
Data and Professional Accurately Accurate Data are not
observations, looking and representation of representation of shown Or are
calculations and accurate the data in tables the data in written inaccurate. No or
analysis representation of and/or graphs. form, but no very poor
the data in tables Tables are tables are calculations are
and/or graphs. labelled and titled. presented. The done. The graphs
Tables are The calculations calculations are are not made. The
labelled and titled. are done with a done with a few relationship
The calculations few mistakes mistakes. between the
are done properly, and/or following Improper or no variables is not
following the the standard rules use of scientific discussed.
standard rules of of error notations, prefixes
error measurements and and units.
measurements and significant Analysis is made
significant figures. Scientific very poorly. The
figures. notations & relationship
Scientific prefixes are used between the
notations & and units are variables is
prefixes are used properly discussed but no
and units are mentioned. patterns, trends or
properly Analysis is made predictions are
mentioned. accurately. The made based on the
Analysis are made relationship data.
neatly and between the
accurately. The variables is
relationship discussed and
between the trends/patterns
variables is logically
discussed and analyzed.
trends/patterns
logically
analyzed.
 Total

COLLEGE OF ENGINEERING & TECHNOLOGY

UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 8 Manual
Generation and Measurement of Impulse Voltage.

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed
 Marks obtained

Instructor Signature

CLO-2 Assemble and examine High voltage, impulse voltage

generation and measurement of performance

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.

SAFETY PRECAUTIONS!!!
It is important and essential that all participants familiarize themselves and strictly follow
all safety precautions described in the Safety Regulations for High Voltage Experiments
section before commencing experiments

Objective
The objective of this experiment is to investigate impulse voltage generation and measurement
using Terco HV equipment. The knowledge gained is a prerequisite for following the High
Voltage Experiments manual.

Note: Extra care is essential in direct voltage experiments, since the high-voltage capacitors in
many circuits retain their full voltage, for a long time even after disconnection. Earthing
regulations are to be strictly observed. Even unused capacitors can acquire dangerous charges!

Reference
Preceding manuals plus:
Terco HV 9152 Digital Impulse Voltmeter Manual

Equipment to be used

COMPONENT DESCRIPTION TERCO TYPE QUANTITY

HV Test Transformer HV9105 1

Control Desk HV9103 1

Smoothing Capacitor HV9112 1

Load Capacitor HV9120 1

Silicon Rectifier HV9111 2

 Measuring Resistor HV9113 1

Charging Resistor HV9121 1

Wave front Resistor HV9122 1

Wave tail Resistor HV9123 1

Sphere Gap HV9125 1

Drive for sphere gap HV9126 1

Insulating Rod HV9124 2

Connecting Rod HV9108 2

Connecting cup HV9109 7

Floor Pedestal HV9110 6

Spacer Bar HV9119 4

Electrode HV9138 1

Earthing Switch HV9114 1

Earthing Rod HV9107 1

DC Voltmeter HV9151 1

Impulse Peak voltmeter HV9152 1

Low Voltage Divider HV9130 1

Test setup
The test setup is based on the DC measurement setup from the preceding experiment with the
addition of a HV 9121 Resistor. To accommodate the extra space needed for the extended
setup, the HV 9113 DC Measuring Resistor is positioned at a 90° angle from the line of the
rectifiers. It is still connected to the HV 9112 Smoothing Capacitor.
The HV 9114 Earthing Switch has been moved to the left of the Smoothing Capacitor to make
room for the extra components to be added.
 Fig. 8.1 Impulse Voltage Measurement Setup Diagram Part 1

The figure below shows the continuation from points A and B in the slightly adjusted DC
measurement setup above. The components below complete the Impulse measuring setup.

Fig. 8.2 Impulse Voltage Measurement Setup Diagram Continued

Introduction
Generation of Impulse Voltages
The identifying time characteristics of impulse voltages are given in Fig. 7.2. In this experiment
lightning impulse voltages with a front time T 1 = 1.2 μs and a time to half value T 2 = 50 μs are
mostly used. This 1.2/50 μs form is the one commonly chosen for impulse testing purposes.

As a rule, impulse voltages are generated in either of the two basic circuits shown in Fig. 7.3.
The relationships between the values of the circuit elements and the characteristic quantities
describing the time-dependent curve are given by the time constants:
τ1 ≈ Re (Cs+Cb) τ2 ≈ Rd{CsCb)/(Cs+Cb)}

Where Cs – Impulse capacitor, Cb- Load Capacitor, Rd- Front Resistor and Re - tail resistor.
For lightning impulse voltages of the standard form 1.2/50 the time constants are
τ1 = 68.22 μs τ2 = 0.405 μs

When designing impulse voltage circuits, one should bear in mind that the capacitance of the test
object is connected parallel to Cb, hence the front time and the efficiency η can be affected. This
has been allowed for in the standards by way of comparatively large tolerances on T1.

Fig. 8.3 Characteristic parameters of standard test impulse voltages

a) Lightning impulse voltage b) switching impulse voltage

Fig. 8.4 Basic Impulse voltage circuits

Breakdown Time-Lag
The breakdown in gases occurs because of an avalanche-like growth of the number of gas
molecules ionized by collision. In the case of gaps in air, initiation of the discharge is affected by
charge carriers which happen to be in a favorable position in the field. If, at the instant when the
voltage exceeds the required ionization onset voltage Ue, a charge carrier is not available at the
appropriate place, the discharge initiation is delayed by a time referred to as the statistical time-
lag ts.
Even after initiation of the first electron-avalanche a certain time elapses, necessary for the
development of the discharge channel which is known as the formative time-lag t a. The total
breakdown time-lag, between over-stepping the value of Ue at time t1 and the beginning of the
voltage collapse at breakdown, compromises these two components:
t1 = ts + ta.
These relationships are shown in Fig. 8.5.

Fig. 8.5 Determination of breakdown time-lag during an impulse voltage breakdown

Experiment and procedure

Investigation of a single-stage Impulse Generator
To ascertain the correct measurement of Impulses, the value displayed on the HV 9152 Impulse
Voltmeter is compared with the level of DC voltage required to cause the breakdown. in order to
create sustained flashovers in a more controlled fashion, the HV 9121 Charging Resistor has
been added. This will lengthen the charging time, creating a delay between flashovers, thus,
allowing for more accurate observations.
Procedure
1. Construct the AC and DC voltage measurement setup as below, note the position of the
additional HV 9121 Charging Resistor, the HV 9114 Grounding Switch and the HV 9113
DC Measuring Resistor.
 Fig. 8.6 Impulse Voltage Measurement step

2. Building to the right of the HV 9112 Smoothing Capacitor, Insert a HV 9119 spacer bar
into the Floor Pedestal. At the other end of the Spacer Bar, add another Floor Pedestal.

The HV 9126 Sphere Gap Drive Unit will be mounted to this Spacer Bar.
3. Position the Sphere Gap Drive box near the right-side Floor Pedestal. The connector for the
Drive Shaft should also be to the right as shown below. Fasten the Drive to the Spacer bar
using the Mounting Bracket Screws (this may need to be adjusted later).

Fig. 8.7 HV 9126 Sphere Gap Drive Placement

4. Stand the HV 9123 Wave tail Resistor upright on the free Floor Pedestal and add a
Connecting Cup.
5. The HV 9125 Spark Gap can now be mounted on the Connection Cups between the
Smoothing Capacitor and the Wave tail Resistor. The Sphere gap Drive Shaft Needs to be
positioned while the Spark gap is lowered into place. Loosen the Drive if required to allow
for better maneuverability. Tighten when finished. The Drive Shaft should rotate freely, and
the closest sphere should move to the left or right when doing so.

Fig 8.8 HV 9125 Sphere Gap and Drive

6. Connect the HV 9126 Drive Signal cable to the HV 9125 Input at the rear of the Control
Desk.

7. Erect the HV 9120 Load capacitor on the last Floor pedestal. This can be done at a right-
angle to save space if required. Place a Connecting Cup on top.

HV 9120
Load
Capacitor

HV 9130
Low Voltage
Divider

Fig 8.9Load capacitor

Note: Position the contact for the Low Voltage Divider nearest the floor.
8. Screw the HV 9130 Low Voltage Divider into place on the HV 9120 Load capacitor.

9. If more than one HV 9130 Low Voltage Divider is available, check that the divider and
capacitor have corresponding numbers.

10. Secure the last section in place by adding the HV 9122 Wave front Resistor.

Fig 8.10 Impulse Setup almost complete - Cables to be organized

11. The setup should now resemble the picture above. It is important for safety and for the
lifetime of the equipment to ensure all cables are neatly organized and if possible, any
excess cable age hung out of the way.

Fig 8.11 Control Desk Cables

12. Double-check all connections and exit the cage, leaving the Earthing Rod positioned across
the doorway, as usual.

13. Switch on the Control Desk. Make sure the regulated voltage is at minimum before
applying any power to the transformer.
 14. Test the Sphere gap Drive Control switches to ensure operation.

Fig 8.12 Sphere Gap Control Switches

15. Reset the voltmeters if desired; check that the correct stage level is set on all instruments.

Note! Before starting the experiment, sound the warning horn to inform people close by that an
experiment is in progress and sudden loud noises can occur.

16. After sounding the horn, power may be provided to the transformer primary and secondary
sides.

17. At several Sphere Gap distances, note the DC voltage levels at which breakdown occurs
and observe and compare the resulting Impulse peak levels. Use the results table to record
this information if desired.

Note! Before switching off the transformer from the Control Desk, remember to decrease the
regulated voltage down to zero.

Note! On entering the HV cage be sure to use the earthing rod to discharge any possible sources
of remaining voltage.
Results

Results Table

Sphere Gap Distance Direct Voltage Breakdown Displayed Peak Impulse

(mm) (kV) Voltage (kV)

20

30

40

50

60

70
Lightning Impulse Measurement through oscilloscope.
Test setup

Fig 8.13 Circuit Diagram

Fig 8.14 Test setup

This experiment assumes that power is supplied to the control desk through X1 and the door
contact has been connected (X11). High voltage AC is generated in the laboratory using the
220V/100kV test transformer (HV9105). This is fed and controlled from the X2 output off the
Control Desk. In this setup, the alternating high voltage is rectified with two HV 9111 rectifiers,
placed in series. The HV9111 capacitor then smooths the rectified DC voltage. For voltage
measurement, one instrument for measuring the primary voltage of the transformer one DC
voltmeter FIV9151 and one impose peak voltmeter HV9152 are provided at each desk. Connect
the appropriate coaxial cable from the measuring resistor HV9113 to the X21 HV9151 input and
HV9130 low voltage divider placed on the load capacitor HV9120 to the X18 HV9152 input. All
measuring instrument input are situated on the rear panel of the control desk. Connect the HV
9131 optical trigger cable between the HV9132 trigger or sphere and the X23 HV9131 trigger
device output also situated on the rear panel of the control desk On top of the smoothing
capacitor, an electrode is placed to provide a good contact surface tor the HV9114 grounding
switch. The HV9114 grounding switch then connected the X12 contact. Connect the HV9126
drive signal cable to the X131-1119125 output at the rear of the control desk.
Connect the 100:1 probe between the X28 impulse voltmeter output on the front of the control
desk and the channel1 input of the HV9159 oscilloscope.

Fig 8.15 Oscilloscope connection

After double-checking all connections and earthing, ensure that everybody has exited the HV
cage. Then proceed with switching on the control desk and set the distance between the spheres
in the HV9125 sphere gap to around 5 cm. Then one full lightning impulse with about 100 kV
charging voltage should be recorded.
Voltage dividers
The HV9120 load capacitor together with the HV9130 makes a voltage divider. The HV9130
low voltage divider is matched with a specific HV9120 load capacitor to make a voltage divider
with a 400:1 ratio.

Fig 8.16 Voltage divider circuit

Oscilloscope settings
There are two ways to make the accurate settings for an impulse measurement on the HV9159
oscilloscope. The correct settings can either be loaded from the internal/external memory or
configured manually. The table below a summary of the oscilloscope settings for measuring a
lightning impulse.

Vertical Controls
Probe 100x
attenuation
Scale 50 V
Position -150 V
Trigger Controls
Mode Edge
Source CH1
Sweep Normal
Measure
Source CH1
Voltage V max
Horizontal Controls
Sample Type Wave tail Wave front
Scale Type 5 µs 200 ns
Position 25 µs
Cursor Setup
Mode Manual
Source CH1

OBSERVATION:
 Assessment Rubric for Lab 8
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-2 Assemble and examine High voltage, impulse voltage generation and measurement
of performance

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total
CLO-4 Write lab notes, effective communication and the design & analysis of the given
problem to perform in the laboratory environment as individual & team.

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)
Data and Professional Accurately Accurate Data are not
observations, looking and representation of representation of shown Or are
calculations and accurate the data in tables the data in written inaccurate. No or
analysis representation of and/or graphs. form, but no very poor
the data in tables Tables are tables are calculations are
and/or graphs. labelled and titled. presented. The done. The graphs
Tables are The calculations calculations are are not made. The
labelled and titled. are done with a done with a few relationship
The calculations few mistakes mistakes. between the
are done properly, and/or following Improper or no variables is not
following the the standard rules use of scientific discussed.
standard rules of of error notations, prefixes
error measurements and and units.
measurements and significant Analysis is made
significant figures. Scientific very poorly. The
figures. notations & relationship
Scientific prefixes are used between the
notations & and units are variables is
prefixes are used properly discussed but no
and units are mentioned. patterns, trends or
properly Analysis is made predictions are
mentioned. accurately. The made based on the
Analysis are made relationship data.
neatly and between the
accurately. The variables is
relationship discussed and
between the trends/patterns
variables is logically
discussed and analyzed.
trends/patterns
logically
analyzed.
 Total

COLLEGE OF ENGINEERING & TECHNOLOGY

UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 9 Manual
Generation and measurement of impulse voltage using trigger sphere gap.

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed

Marks obtained
 Instructor Signature

CLO-2 Assemble and examine High voltage, impulse voltage

generation and measurement of performance

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.

SAFETY PRECAUTIONS!!!
It is important and essential that all participants familiarize themselves and strictly follow
all safety precautions described in the Safety Regulations for High Voltage Experiments
section before commencing experiments

Objective
The objective of this experiment is to investigate the operation of the HV 9132 trigger
Sphere.

Equipment to be used
As for Experiment 4, with the addition of the HV 9132 Trigger Sphere and HV 9131 Optical
Trigger cable.

Test setup
The test setup is the same as the previous experiment except for the 9132 Trigger Sphere.

Fig. 9.1 Trigger Sphere and Cable

Trigger Sphere
The HV 9132 Trigger Sphere replaces the passive sphere nearest the transformer in the HV
9125.

HV 9132
Trigger Sphere

HV 9131
Optical Trigger
Cable

Fig. 9.2 Trigger Sphere and Cable

Introduction
Triggering of Impulse Voltages
In order to study Impulse more closely, it is beneficial to have greater control over the
breakdown timing.
Because of the extremely short times involved, it may be hard to capture the desired information.
The trigger sphere not only provides a means of knowing when the breakdown will occur but
highlights one of the key characteristics of the breakdown.

Experiment and procedure

Investigation of a single-stage Impulse Generator
The Control Desk front panel houses the trigger button for the Trigger Sphere. Pressing this
button sends a light pulse along the fiber-optic cable to the Trigger Sphere where the inbuilt
electronics provide current to a sparkplug. The sparkplug ignites, providing the extra voltage
needed to initiate a breakdown in the air gap.
Procedure
1. Starting with the setup for Experiment 4, unscrew and remove the sphere. Every care
should be taken so that no marks are made on the sphere. Store this in a safe place.

2. Locate the trigger button on the trigger unit, on the front panel of the Control Desk. Push
the button (with the Control Desk switched on) and check that a light pulse can be seen in
the HV 9131 rear connector.

Connect fibre optic cable to control desk and check that the pulse can now be seen at the other
end of the cable.

3. Open trigger sphere and connect 2 x 9V batteries. Close again by twisting into place.
 4. Connect the fiber optic cable to the trigger sphere.

5. Test the Trigger Sphere, a spark should be seen and heard from the spark plug on pressing
the trigger button.

Note: Do not hold the trigger sphere near or on the spark plug!

Fig. 9.3 Trigger Sphere trigger

6. If the test is successful, the Trigger Sphere is OK for use. Remove the cable. Switch off the
Control Desk.

Note: On entering the HV cage be sure to use the earthing rod to discharge any possible sources
of remaining voltage.

7. Mount the Trigger Sphere in the HV 9125 Sphere gap by screwing into place, position the
optic cable input in the opening.

8. Insert and fasten the fiber optic cable in the trigger sphere.

9. On leaving the HV area, leave the Discharge Rod across the doorway and lock the door.

Note: Before starting the experiment, sound the warning horn to inform people close by that an
experiment is in progress and sudden loud noises can occur.

10. Try triggering a flashover at different distances and voltages. Note how much less voltage is
required to create a standing arc than to spontaneously jump the air gap.
OBSERVATION:
 Assessment Rubric for Lab 9
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-2 Assemble and examine High voltage, impulse voltage generation and measurement
of performance

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total
CLO-4 Write lab notes, effective communication and the design & analysis of the given
problem to perform in the laboratory environment as individual & team.

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)
Data and Professional Accurately Accurate Data are not
observations, looking and representation of representation of shown Or are
calculations and accurate the data in tables the data in written inaccurate. No or
analysis representation of and/or graphs. form, but no very poor
the data in tables Tables are tables are calculations are
and/or graphs. labelled and titled. presented. The done. The graphs
Tables are The calculations calculations are are not made. The
labelled and titled. are done with a done with a few relationship
The calculations few mistakes mistakes. between the
are done properly, and/or following Improper or no variables is not
following the the standard rules use of scientific discussed.
standard rules of of error notations, prefixes
error measurements and and units.
measurements and significant Analysis is made
significant figures. Scientific very poorly. The
figures. notations & relationship
Scientific prefixes are used between the
notations & and units are variables is
prefixes are used properly discussed but no
and units are mentioned. patterns, trends or
properly Analysis is made predictions are
mentioned. accurately. The made based on the
Analysis are made relationship data.
neatly and between the
accurately. The variables is
relationship discussed and
between the trends/patterns
variables is logically
discussed and analyzed.
trends/patterns
logically
analyzed.
 Total

COLLEGE OF ENGINEERING & TECHNOLOGY

UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 10 Manual
Disruptive Discharge Voltage Tests with Alternating Current.

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed

Marks obtained
 Instructor Signature

CLO-3 Express knowledge and analysis of Disruptive

discharge voltages

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.

SAFETY PRECAUTIONS!!!
It is important and essential that all participants familiarize themselves and strictly follow
all safety precautions described in the Safety Regulations for High Voltage Experiments
section before commencing experiments
Objective

In order to transport electrical power and avoid flashovers and blackouts, good knowledge of
how insulators should be selected and dimensioned is necessary. The dimensioning of insulators
is critical in terms of electrical, mechanical and environmental stress. Outdoor insulators can
become heavily coated with dirt and chemicals by environmental pollution. The insulators will
be polluted with industrial contaminants, coastal fog, natural dust, bird feces, etc. The
contaminant will be partially dissolved forming a conductive layer Leakage current that flows
along the surface will increase and may eventually cause flashovers Service experience shows
that pollution flashover is one of the main natural calamities harming high-voltage transmission
lines. This test will provide an insight to now contamination affects the insulation capability of
the various insulators.

Reference

Terco HV 9150 Digital AC Voltmeter Manual

Terco HV 9103 Control Desk Manual

Equipment to be used

COMPONENT
TERCO TYPE No. QUANTITY
DESCRIPTION

Control Desk HV9103 1

AC Peak Voltmeter HV9150 1

HV Test Transformer HV9105 1

Load Resistor HV9127 1

Measuring Capacitor HV9141 1

Connecting Rod HV9108 1

Connecting Cup HV9109 2

Floor Pedestal HV9110 2

HV Connection HV9106 1

HV Insulator 1

Introduction
Setting up the HV experiment

This experiment assumes that power is supplied to the control desk and the door contact has been
connected. High Voltage AC is generated in the Laboratory using the 220V/100kV Test
Transformer (HV9105). This is fed and controlled from the Control Desk. For voltage
measurement, one instrument for measuring the primary voltage of the transformer and one AC
peak voltmeter HV91 50 are provided at each desk Connect the appropriate coaxial cable from
the Measuring Capacitor HV 9141 to the HV 9150 input, situated on the rear panel of the Control
desk.
Experiment and procedure

Preparation of the test object for dry test

The test object shall be carefully cleaned before testing for the first time so that all traces of dirt
and grease are removed. Water, preferably heated to 50 °C with the addition of trisodium
phosphate or another detergent, shall be used, after which the insulator is to be thoroughly rinsed
with tap water. The insulating surfaces can be considered sufficiently clean and free of grease or
other contaminating material if large continuous wet areas are observed during wetting, the
insulating parts of the test object shall not be touched by hand.

Preparation of the test object for artificial solid layer contamination test

After cleaning the test object as described a contamination layer is applied to the insulator
surface using slurry consisting of water, an inert material such as kaolin, and an appropriate
amount of sodium chloride (NaCl).

The slurry composition consists of:

 40 g kaolin
 1000 g tap water
 35 g NaCl of commercial purity

The slurry described above shall be applied by spraying it or pouring it onto the dry insulator to
obtain a reasonably uniform layer. Alternatively, the insulator may be dipped in the slurry.
Provided its size permits this operation. Another technique is to apply the contamination by a
small paint brush

Procedure

The first lest will be carried out in and conditions where the insulators will be clean and dry the
test procedure will then be repeated that this time with contaminated insulators so that test results
can be compared. The voltage shall be applied to the test object starting at a value sufficiently
low to prevent any effect of overvoltage due to switching transients. It should be raised
sufficiently slowly to permit accurate reading of the measuring instrument but not so slowly as to
cause unnecessarily prolonged stress on the test object at the test voltage. These requirements are
met in general if the rate of rise above 75% of the estimated final test voltage is about 2% of the
test voltage per second The voltage shall be applied and raised until a disruptive discharge occurs
on the test object The value of the test voltage reached just prior to the disruptive discharge shall
be recorded.

Table 10.1 Insulator voltage ratings

Glass disc Glass disc Ceramic Line Composite Line

One disc Two discs Post Post

Rated system voltage 12 24 24 24

Dry flashover voltage 80 160 80 110
Wet flashover voltage 50 90 60 95
Positive impulse 125 235 130 150

flashover
Negative impulse 130 245 155 170

flashover
Low frequency 130

Puncture voltage

Results

Insulator Type Flashover voltage Flashover voltage Decrease (%)

Dry/Clean (kV) Contaminated (KV)

Glass disc (one disc)
Ceramic Line post
Composite Line post
OBSERVATION/DISCUSSION:
 Assessment Rubric for Lab 10
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-3 Express knowledge and analysis of Disruptive discharge voltages

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total
CLO-4 Write lab notes, effective communication and the design & analysis of the given
problem to perform in the laboratory environment as individual & team.

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)
Data and Professional Accurately Accurate Data are not
observations, looking and representation of representation of shown Or are
calculations and accurate the data in tables the data in written inaccurate. No or
analysis representation of and/or graphs. form, but no very poor
the data in tables Tables are tables are calculations are
and/or graphs. labelled and titled. presented. The done. The graphs
Tables are The calculations calculations are are not made. The
labelled and titled. are done with a done with a few relationship
The calculations few mistakes mistakes. between the
are done properly, and/or following Improper or no variables is not
following the the standard rules use of scientific discussed.
standard rules of of error notations, prefixes
error measurements and and units.
measurements and significant Analysis is made
significant figures. Scientific very poorly. The
figures. notations & relationship
Scientific prefixes are used between the
notations & and units are variables is
prefixes are used properly discussed but no
and units are mentioned. patterns, trends or
properly Analysis is made predictions are
mentioned. accurately. The made based on the
Analysis are made relationship data.
neatly and between the
accurately. The variables is
relationship discussed and
between the trends/patterns
variables is logically
discussed and analyzed.
trends/patterns
logically
analyzed.
 Total

COLLEGE OF ENGINEERING & TECHNOLOGY

UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 11 Manual
Disruptive Discharge Voltage Tests with Direct Current.

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed

Marks obtained
 Instructor Signature

CLO-3 Express knowledge and analysis of Disruptive

discahrge voltages

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.

SAFETY PRECAUTIONS!!!
It is important and essential that all participants familiarize themselves and strictly follow
all safety precautions described in the Safety Regulations for High Voltage Experiments
section before commencing experiments
Objective
High voltage direct current transmission has many advantages over alternating current. The most
prominent advantages are that high voltage dc is able to transmit large amounts of power over
long distances with lower capital costs and with lower losses than AC. One key issue, however,
for the design of the HVDC transmission lines is to select appropriate insulators. More
contaminants accumulate on DC insulators because of the static electric field of DC voltage,
which is 1.2-1.5 times higher than that on AC insulators under the same atmospheric
environment, moreover, the DC pollution flashover voltages will decrease more than AC
voltages with an increase in the degree of pollution. The arc floating led by a steady DC arc will
bridge the sheds of insulators, which reduce the pollution flashover voltages of DC insulator
strings and cause effective leakage distances of insulators less than those of the geometrical
leakage distances. This test will provide an insight to how current contamination affects into the
insulation capability of the various insulators under direct
Reference
Terco HV 9151 Digital DC Voltmeter Manual
Terco HV 9103 Control Desk Manual
Equipment to be used

COMPONENT
TERCO TYPE No. QUANTITY
DESCRIPTION

Control Desk HV9103 1

AC Peak Voltmeter HV9150 1

DC Digital Voltmeter HV9151 1

 HV Test Transformer HV9105 1

Silicon Rectifier HV9111 2

Load Resistor HV9127 1

Impulse Capacitor HV9112 1

Measuring Resistor HV9113 1

Measuring Capacitor HV9141 1

Top Electrode HV9138 1

Earthing Switch HV9114 1

Insulating rod HV9124 2

Connecting Rod HV9108 5

Connecting Cup HV9109 7

Floor pedestal HV9110 7

HV Connection HV9106 1

HV Insulator 1

Test setup
 Fig. 11.1 Principle Circuit Diagram
Introduction

Setting up the HV experiment

This experiment assumes that power is supplied to the control desk and the door contact has been
connected. High voltage AC is generated in the laboratory using the 220V/100kV test
transformer (HV9105). This is fed and controlled from the control desk. In this setup, the
alternating high voltage is rectified with two HV 9111 rectifiers, placed in series. The HV 9112
capacitor then smoothed the rectified DC voltage. For voltage measurement, one instrument for
measuring the primary voltage of the transformer, one AC peak voltmeter HV 9150 and a DC
voltmeter HV9151 are provided at each desk. Connect the appropriate coaxial cable from the
measuring capacitor HV 9141 to the HV 9150 input and the measuring resistor HV 9113 to the
HV 9151 input, situated on the rear panel of the control desk. On top of the smoothing capacitor,
an electrode is placed to provide a good contact surface for the HV 9114 grounding switch. The
HV 9114 grounding switch is then connected to the control desk.

Fig. 11.2 Two different type of circuits for DC Voltages

1) Line Post Composite/Ceramic insulator
2) Suspension glass Disc

Experiment and procedure

Preparation of the test object
The test object shall be carefully cleaned before testing for the first time, so that all traces of dirt
and grease are removed. Water, preferably heated to 50 °C with the addition of trisodium
phosphate or another detergent, shall be used, after which the insulator is to be thoroughly rinsed
with tap water. The insulating surfaces can be considered sufficiently clean and free of grease or
other contaminating material if large continuous wet areas are observed during wetting. After
cleaning, the insulating parts of the test object shall not be touched by hand.
Preparation of the test object for artificial solid layer contamination test
After cleaning the test object as described previously a contamination layer is applied to the
insulator surface using a slurry consisting of water, an inert material such as kaolin, and an
appropriate amount of sodium chloride (NaCl).
The slurry composition consists of:
(a). 40 g kaolin
(b). 1000 g tap water
(c). 35 g NaCl of commercial purity
The slurry described above shall be applied by spraying it or flowing it onto the dry insulator, to
obtain a reasonably uniform layer. Alternatively, the insulator may be dipped in the slurry,
provided its size permits this operation. Another technique is to apply the contamination by a
small paint brush.
Procedure
The first time the test will be carried out in good conditions where the insulators will be clean
and dry. The test procedure will then be repeated but this time with contaminated insulators, so
that test results can be compared.
The voltage shall be applied to the test object starting at a value sufficiently low to prevent any
effect of over voltages due to switching transients. It should be raised sufficiently slowly to
permit accurate reading of the measuring instrument, but not so slowly as to cause unnecessarily
prolonged stress on the test object at the test voltage. These requirements are met in general if the
rate of rise above 75% of the estimated final test voltage is about 2% of the test voltage per
second. The voltage shall be applied and raised until a disruptive discharge occurs on the test
object. The value of the test voltage reached just prior to the disruptive discharge shall be
recorded.
Table 11.1 Insulator voltage ratings
Glass Glass disc Two Ceramic Line Composite Line
disc One disc discs Post Post

Rated system 12 24 24 24
voltage
Dry flashover 80 160 80 110
voltage
Wet flashover 50 90 60 95
voltage
Positive impulse 125 235 130 150
flashover
Negative impulse 130 245 155 170
flashover
Low frequency 130
Puncture voltage

Results
Insulator type Flashover voltage Flashover voltage Decrease
Dry/Clean (kV) Contaminated (KV) (%)
Glass disc (one disc)
Ceramic Line post
Composite Line post

OBSERVATION:
 Assessment Rubric for Lab 11
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-3 Express knowledge and analysis of Disruptive discharge voltages

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total
CLO-4 Write lab notes, effective communication and the design & analysis of the given
problem to perform in the laboratory environment as individual & team.

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)
Data and Professional Accurately Accurate Data are not
observations, looking and representation of representation of shown Or are
calculations and accurate the data in tables the data in written inaccurate. No or
analysis representation of and/or graphs. form, but no very poor
the data in tables Tables are tables are calculations are
and/or graphs. labelled and titled. presented. The done. The graphs
Tables are The calculations calculations are are not made. The
labelled and titled. are done with a done with a few relationship
The calculations few mistakes mistakes. between the
are done properly, and/or following Improper or no variables is not
following the the standard rules use of scientific discussed.
standard rules of of error notations, prefixes
error measurements and and units.
measurements and significant Analysis is made
significant figures. Scientific very poorly. The
figures. notations & relationship
Scientific prefixes are used between the
notations & and units are variables is
prefixes are used properly discussed but no
and units are mentioned. patterns, trends or
properly Analysis is made predictions are
mentioned. accurately. The made based on the
Analysis are made relationship data.
neatly and between the
accurately. The variables is
relationship discussed and
between the trends/patterns
variables is logically
discussed and analyzed.
trends/patterns
logically
analyzed.
 Total

COLLEGE OF ENGINEERING & TECHNOLOGY

UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 12 Manual
Lighting Impulse Disruptive Discharge Test.

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed

Marks obtained
 Instructor Signature

CLO-3 Express knowledge and analysis of Disruptive

discahrge voltages

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.

SAFETY PRECAUTIONS!!!
It is important and essential that all participants familiarize themselves and strictly follow all
safety precautions described in the safety Regulations for High Voltage Experiments section
before commencing experiments.
Objective
Overvoltage caused by lightning must be considered when designing high voltage transmission
lines. When any over voltage appears in the electrical power system, then there may be a chance
of failure of its insulation system. This test will provide an insight different insulator is able to
withstand overvoltage caused by the 1.2/50 lightning impulse wave.
Reference
Terco HV9103 Control Desk Manual
Terco HV 9152 Digital Impulse Voltmeter Manual

Equipment to be used

COMPONENT
TERCO TYPE No. QUANTITY
DESCRIPTION
Control Desk HV9103 1
AC Peak Voltmeter HV9150 1
DC Voltmeter HV9151 1
Impulse Voltmeter HV9152 1
Trigger Device HV9131 1
HV Test Trans former HV9105 1
Charging Resistor HV9121 1
Measuring Capacitor HV9141 1
Silicon Rectifier HV9111 1
Impulse Capacitor HV9112 1
Measuring Resistor HV9113 1
Wave Tail Resistor HV9123 1
Wave Front Resistor HV9122 1
Load Capacitor HV9120 1
Sphere Gap HV9125 1
 Low Voltage Divider HV9130 1
Electronic Trigger Sphere HV9132 1
Driver for Sphere Gap HV9126 1
Top Electrode HV9138 1
Earthing Switch HV9114 1
Insulating rod HV9124 1
Connecting Rod HV9108 1
Floor Pedestal HV9110 1
HV Connection HV9110 1
HV Insulator HV9106 1

Test Setup

Fig. 12.1 Principle Circuit Diagram

Test Setup
 Fig. 12.2 Test Setup

Introduction
Setting up the HV Experiment
This experiment assumes that power is supplied to the control desk and the door contact has been
connected. High voltage AC is generated in the laboratory using the 220V/100kV test
transformer (HV9105). This is fed and controlled from the Control Desk. In this setup, the
alternating high voltage is rectified with two HV 91 11 rectifiers, placed in series. The HV 9112
capacitor then smoothes the rectified DC voltage. For voltage measurement, one instrument for
measuring the primary voltage of the transformer, one AC peak voltmeter HV9141 to the
HV9150 input, measuring resister HV 9113 to the HV 9151 input and HV9130 low voltage
divider placed on the load capacitor HV9120to the HV9152. All measuring instrument inputs are
situated on the rear panel of the control desk. Connect the HV9131 optical trigger cable between
the HV9132 trigger sphere and the HV9131trigger device also situated on the rear panel of the
control desk. One top of the smoothing capacitor, an electrode is placed to provide a good
contact surface for the HV9114 grounding switch. The HV 9114 grounding switch is then
connected to the control desk. Connect the HV9126 drive signal cable to the HV 9125 input at
the rear of the control desk.
Generation of Impulse Voltages
The identifying time characteristics of impulse voltages are given in Fig. 2.3. In this experiment
lightning impulse voltages with a front time T 1=1.2 μs and a time to half value T2=50μsare used.
The 1.2/50 μs is defined as standard in IEC 60060-1. The Triggering device HV9131 connected
as in Fig. 2.2 to the electronic trigger sphere HV 9132 via fibre-optic cable allows precise
triggering of the impulse generator at an accurately preset charging voltage.

Fig. 12.3 Characteristics parameter of lightening impulse voltage

Experiment and procedure

Preparation of the test object

The test object shall be carefully cleaned before testing for the first time, so that all traces of dirt
and grease are removed. Water, preferably heated to 50°C with the addition of trisodium
phosphate or another detergent, shall be used, after which the insulator is to be thoroughly rinsed
with tap water. The insulating surfaces can be considered sufficiently clean and free of grease or
other contaminating material if large continuous wet areas are observed during wetting.

Procedure

The first test will be carried out with a positive lightning impulse. The test procedure will then be
repeated but this time with the HV9111 rectifiers placed the opposite way so the insulators can
be exposed to a negative lightning impulse.
Three impulses of the specified shape and polarity shall be applied to the test object starting at
the rated lighting impulse withstand voltage level. The value of the test voltage reached at the
disruptive discharge shall be recorded.
Table 12.1 Insulator voltage ratings

Glass Glass Two Ceramic Line Composite Line

Disc discs Post Post
One disc
Rated system voltage 12 24 24 24
Dry flashover voltage 80 160 80 110
Welt flashover voltage 50 90 60 95
Pos impulse flashover 125 235 130 150
Neg impulse flashover 130 245 155 170
Low freq Puncture voltage 130 - - -

Results
Insulator type Impulse Flashover Impulse flashover Difference
Positive (kV) Negative (kV) (kV)
Glass disc (one disc)
Glass disc (two disc)
Ceramic Line post
Composite Line post

OBSERVATION:
 Assessment Rubric for Lab 12
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-3 Express knowledge and analysis of Disruptive discharge voltages

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total
CLO-4 Write lab notes, effective communication and the design & analysis of the given
problem to perform in the laboratory environment as individual & team.

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)
Data and Professional Accurately Accurate Data are not
observations, looking and representation of representation of shown Or are
calculations and accurate the data in tables the data in written inaccurate. No or
analysis representation of and/or graphs. form, but no very poor
the data in tables Tables are tables are calculations are
and/or graphs. labelled and titled. presented. The done. The graphs
Tables are The calculations calculations are are not made. The
labelled and titled. are done with a done with a few relationship
The calculations few mistakes mistakes. between the
are done properly, and/or following Improper or no variables is not
following the the standard rules use of scientific discussed.
standard rules of of error notations, prefixes
error measurements and and units.
measurements and significant Analysis is made
significant figures. Scientific very poorly. The
figures. notations & relationship
Scientific prefixes are used between the
notations & and units are variables is
prefixes are used properly discussed but no
and units are mentioned. patterns, trends or
properly Analysis is made predictions are
mentioned. accurately. The made based on the
Analysis are made relationship data.
neatly and between the
accurately. The variables is
relationship discussed and
between the trends/patterns
variables is logically
discussed and analyzed.
trends/patterns
logically
analyzed.
 Total

COLLEGE OF ENGINEERING & TECHNOLOGY

UNIVERSITY OF SARGODHA

EE 422: High Voltage Engineering

Lab 13 Manual
Insulation Test for Transformer Oil.

Instructors & Demonstrators: Engr. Muhammad Qamar ud Din, Muhammad Hamza

Student Name

Roll No.

Date Performed

Marks obtained
 Instructor Signature

CLO-3 Express knowledge and analysis of Disruptive

discahrge voltages

CLO-4 Write lab notes, effective communication and the

design & analysis of the given problem to perform in the
laboratory environment as individual & team.

SAFETY PRECAUTIONS!!!
it is important and essential that all participants familiarize themselves and strictly follow all
safety precautions described in ANNEXURE-A before commencing experiments
Objective
Insulation arrangement for high voltage usually contains liquid or solid insulating materials
whose breakdown strength is many times that of atmospheric air. For practical application of
these materials not only their physical properties but also their technological and constructional
features must be considered. The topics discussed in this experiment are:
Fiber-bridge breakdown
Equipment to be used

COMPONENT TERCO TYPE no. QUANTITY

DESCRIPTION
HV test transformer HV9105 1
Control Desk HV9103 1
Measuring Capacitor HV9141 1
AC peak voltmeter HV9150 1
Connecting rod HV9108 1
Connecting cup HV9109 1
Floor pedestal HV9110 1
Oil testing cup HV9137 1
Earthing rod HV9107 1
Measuring sphere gap HV9133 1
Spacer bar for HV9133 HV9118 1

Test setup
 Fig.13.1 Test setup for Fiber-Bridge Breakdown in insulating Oil
Introduction
Fiber-Bridge Breakdown in insulating oil
Every technical liquid insulating material contains macroscopic contaminants in this form of
fibrous element of cellulose, cottoned. Particular when these element have absorbed moisture
from the insulating liquid, force act upon them, moving to the region of higher field as strength
as well as aligning them in the direction of E. Charges of opposite polarity are induced at the end
of short fiber, which causes a torque and forces alignment of the fibrous element in the direction
of field lines. In this way, fiber-bridge comes into existence.
A conducting channel is created which can be heated due to resistance loss to such an extent that
moisture contained in the element evaporates. The breakdown which then sets in comparatively
low voltages can be described as local thermal breakdown at a defect
The mechanism is of such great technical significance that in the electrode arrangement for high
voltages pure oil sections have to be avoided. This is achieved by the introducing insulating
screens, perpendicular to the direction of field strength. In the extreme case consistent
application of this principle leads to oil-impregnated paper insulation which is the most
important and very high stress able dielectric for cable capacitors and transformer

Experiment and procedure

Fiber-Bridge Breakdown in insulating oil

In the setup used in the experiment the upper electrode is replaced by a sphere e.g. of 20 mm
diameter and the spacing is set to few cm. Some slightly moistened black threads of cotton 5mm
long are contained in the coil. A voltage is about 10kv applied between the sphere and plate
within few seconds result in the alignment of the threads in the direction of field a fibre-bridge is
established which can neither initiate nor accelerate a breakdown. The two photographs of the
model experiment shown in fig 13.2 indicate clearly the extent to which oil Gap in high-voltage
apparatus, which are not subdivided are exposed to risk by dissociation product and other solid
particles.

Fig. 13.2. Model experiment showing fiber-bridge formation in insulating oil

a) fibers before switching the voltage on
b) fiber-bridge 1 minute after switching the voltage on

OBSERVATION:
 Assessment Rubric for Lab 13
Method of Evaluation: Lab report.
Outcomes Assessed:
CLO-3 Express knowledge and analysis of Disruptive discharge voltages

Performance 5 Excellent 4 Good 3 Satisfactory 2-1 Needs Marks

Improvement
Participation Used time well in Used time pretty Did the lab but Participation was
lab and focused well. Stayed did not appear minimal OR
attention on the focused on the very interested. student was
experiment. experiment most Sometimes hostile about
Routinely of the time. provides useful participating.
provides useful Usually provides ideas when Rarely provides
ideas when useful ideas when participating in useful ideas when
participating in participating in the group and in participating in
the group and in the group and in classroom the group and in
classroom classroom discussion. A classroom
discussion. A discussions. A satisfactory group discussion. May
definite leader strong group member who does refuse to
who contributes a member who tries what is required. participate.
lot of effort. hard.
Connections Actively looks for Refine solutions Does not suggest Does not try to
and suggests suggested by or refine solve problems or
solutions to others. solutions, but is help others solve
problems. (Individual) willing to try out problems. Let’s
(Individual). Complete and solutions others do the
Complete and error free suggested by work. (Individual)
error free connections done. others. Many mistakes in
connections done No neatness in the (Individual) connections, no
neatly using circuit and / or Few mistakes in neatness in the
appropriate sized difficult to connections. But circuit and/or
wires, easy to comprehend for neatly done, easy difficult to
comprehend for the instructor. to comprehend for comprehend for
the instructor. (Group) the instructor. the instructor.
(Group). (Group) (Group)
Running the Student is well Student is Below average Poor level of
experiment prepared with the averagely theoretical theoretical
theoretical prepared with the knowledge. knowledge.
knowledge related theoretical (Individual) (Individual)
to the experiment. knowledge. Not following the Not able to run
(Individual) (Individual) instructions the experiment
Experiment is run Experiment is run mentioned on lab and/or incorrect
step by step and step by step and manual, but still readings.
flawlessly flawlessly manages to run
according to the according to the the experiment
procedure procedure anyway and/or
provided on the provided on the semi correct
lab manual. lab manual. readings set.
Correct reading Correct reading (Group)
set. (Group) set. (Group)

Total