MODEL: HC-50K/3

HIGH CURRENT TEST SET

OPERATING INSTRUCTIONS

ADWEL International Ltd.

60 Ironside Crescent, Unit 9
Toronto, ON M1X 1G4
Telephone: (416) 321-1988 Fax: (416) 321-1991
 INDEX
SECTION PAGE

1. GENERAL DESCRIPTION 1

2. MODE OF OPERATION AND DESIGN 2

3. TIMER OPERATION 6

4. TEST LEADS AND CONNECTIONS 7

5. OUTPUT LEADS AND CONNECTIONS 8

6. OPERATING INSTRUCTIONS 10

7. TAP SETTINGS 16

8. TEST PROCEDURES 17

8.2 OPERATING CHARACTERISTICS OF MOLDED

CASE CIRCUIT BREAKERS 26
8.3 OPERATING CHARACTERISTICS OF MOTOR
OVERLOAD RELAYS 27

9. MAINTENANCE MANUAL

10. APPENDIX - HC50CONT.SCH

- HC50POWR.SCH
1. GENERAL DESCRIPTION

The ELECTRICAL TESTING INSTRUMENTS', Model HC-50K/3 HIGH CURRENT

TEST SET is specifically designed to test and calibrate:
1. LOW VOLTAGE POWER CIRCUIT BREAKERS

2. MOLDED CASE CIRCUIT BREAKERS

3. MOTOR OVERLOAD RELAYS

The Test Set will simulate overload conditions and measure the
reaction time of the test specimen.
The Test Set is supplied in a three unit construction for ease
of manoeuvre-ability.

The Test Set consists of:

1) A CONTROL UNIT containing all control circuits and
switches, metering and timing instruments, input circuit
breaker, main contactor and a tapped auto-transformer.
2) A HIGH CURRENT SUPPLY containing a large step-down
output transformer isolated from the line and the
current measuring transformer.

3) A FINE ADJUST section contains a continuously variable

auto-transformer, a high current step-down transformer
and a line voltage meter.

The tapped auto-transformer in the control section with its 5

course and 5 fine taps is used as the main coarse control and
feeds power from the line to the High Current Supply Transformer
and to the fine control section. Current fed to the load,
therefore, depends not only on the load impedance, as
represented by the device under test and the means of
connection, but also on the fine and coarse tap setting on the
auto-transformer and the position of the fine control.
Because this High Current Test Set may be considered a current
source, the lowest voltage that will supply the desired test
current should be used.

Load current will thus be varied stepwise by the choice of

transformer taps and continuously by the variable auto-
transformer.

OPERATING INSTRUCTIONS 1 MODEL: HC-50K/3

2. MODE OF OPERATION AND DESIGN

A power source of 208 to 240 or 440 or 600 volts, 60 Hz., single

phase is required to provide operating power to this unit. The
Test Set is protected by a thermal-magnetic breaker in the
primary (CB-1). This breaker also serves as the main ON-OFF
switch.

CR-1 Is the main contactor. It provides power to the High

Current supply via contacts "A" and "B" and self-holding
power via contact "C" in the MAINT. C.A. and MAIN. N.O.
modes.
TR-1 Provides line isolation for the timer power supply and all
control circuitry.

TR-2 Is a multi-tap auto-transformer variable in the primary to

accommodate a variety of input voltages and variable in the
secondary for current output control.

TR-3 Is a precision current metering transformer inserted in the

common output control lead.
TR-4 Is the High Current supply transformer, or the main current
source capable of supplying 50,000 amps.

TR-5 Is a precision multitap current metering transformer.

TR-6 Is 5:1 step-down transformer used in conjunction with VT-1
to provide 0-24 volts at a maximum current of 500 amperes
as fine control for the main output transformer.
The 0-120V out can also be used independently wherever 0-
120 is required @ 50 amperes.

VT-1 Provides continuously variable 0-120V at a max. current of

50 amperes.

TIMER:

The timer is a 6 digit high accuracy device. The elapsed time

is indicated in seconds and milliseconds. Start and stop
commands are given to the timer by a second set of contacts on
the START and STOP push button actuators. The timer can be
reset by the RESET button actuator.

OPERATING INSTRUCTIONS 2 MODEL: HC-50K/3

 ON-OFF This is a high current circuit breaker which is the
main
POWER SWITCH input switch controlling all input power to the
unit. It is located on the left side of the
control unit.
POWER-ON (6) This light indicates that the main switch is
closed and that
LIGHT the unit is ready to be used.
TEST-ON (8) This light indicates that the test set is in
operation.
LIGHT The timer will be running and accumulating
elapsed time.
START (9) This switch will start timer operation and
current flow
PUSHBUTTON when depressed. (see timer operation selector).
STOP (11) This switch will stop test current flow and timer
operation
PUSHBUTTON when depressed.
CONTACTS (13) These binding posts are connected to the contact
circuit
BINDING POSTS of the device under test to stop the timer and
de-energize current flow.

RESET-LIGHT (10) This switch resets the Test Set for the
next test and the
PUSHBUTTON digital timer to 000.000. The RESET light
indicates that the
Test Set was operated and requires to be reset.
INPUT This panel allows selection of input voltages. It is
located
SELECTOR on the left side, INSIDE the Main Control Unit.

AMMETER (1) The 6 range ammeter is a precision moving vane

instrument true RMS responding and indicating.
It is switched into the secondary of the
precision multi-tap current transformer by switch
S-3.

VOLTMETER (2) The two range Voltmeter is used across the high
current output terminals. This instrument
provides useful information about the impedance-
match of the Test Set to the device under test.
A high voltage indication will make the operator
aware of bad connections or excessive lead length
to the device under test.

TIMER (3) The precision digital timer indicates elapsed

time from 1 millisecond to 999.999 seconds.

CONTROL (7) The control circuit breaker protects the control

and function
CIRCUIT circuit.
BREAKER

OPERATING INSTRUCTIONS 3 MODEL: HC-50K/3

 PANEL CONTROLS AND OPERATING FUNCTIONS
(as shown in Figure 1)

1. 6 Range Ammeter

2. 2 Range Voltmeter

3. DIGITAL TIMER

4. Voltmeter Range Switch

5. Ammeter Range Switch

6. POWER-ON Light

7. Control Circuit Breaker

8. TEST-ON Light

9. TEST-START Actuator

10. RESET - Light and Actuator

11. STOP - Actuator

12. FUNCTION SWITCH

13. Binding Posts for Breaker Contacts

OPERATING INSTRUCTIONS 4 MODEL: HC-50K/3

OPERATING INSTRUCTIONS 5 MODEL: HC-50K/3
3. TIMER OPERATION SELECTOR

A three position FUNCTION switch (12) selects the timer

operating mode.
There are three (3) types of operating modes. Selection of
timer operation depends upon the device to be tested and the
relationship of its contacts which are connected to the control
circuit of the Test Set.
MAINT. C.A. When the device to be tested has no contacts
other than
Current Actuated those involved in the passing of test
current, (such as single pole circuit breakers),
this type of operation is used.
In this position, the timer will run from the
initiation of the test until current flow from
the output of the test unit is interrupted by the
device under test.
In the maintained current-actuated mode, contacts 1 and 2 and 3
and 4 of S-1 are closed. The coil of CR-1 is energized as the
START button is pressed. If current is flowing in the output
(min. 20% of F.S. on the ammeter), RY-1 will pull in and hold
CR-1 via its own contact "C" until the output current is
interrupted causing the opening of SSR or the STOP button is
depressed. The timer will indicate the time elapsed.

MAINT. N.C. In this position, when the START button is

pressed, the control circuit is sealed-in to
MAINTAIN the flow of test current.
The normally-closed contacts of the device to be
tested (such as an OVERCURRENT relay) will be
connected to the binding posts marked CONTACTS.

In the maintained-normally closed mode, contacts 4 and 3 and 7

and 8 of S-1 are closed. The coil of CR-1 is energized as the
START button is pressed. CR-1 will pull in and hold via its own
contact "C" and the set of normally-closed contacts on the
CONTACTS terminals until the contacts are opened or the STOP
button is depressed. The timer will indicate the time elapsed.

MOM. In this position there is no seal-in and the test

output is produced only as long as the START
button is held. Contacts 5 and 6 on S-1 are
closed. This position is used for setting test
currents prior to the actual test runs.

OPERATING INSTRUCTIONS 6 MODEL: HC-50K/3

4. TEST LEADS AND CONNECTIONS

GENERAL DISCUSSION

The proper selection of input and output leads is vital to the

most efficient use of High Current test sets. The input leads
must be large enough to maintain the rated input voltage at the
input terminals of the unit under test conditions. The output
leads must be designed to carry the output current from the Test
Set to the device under test with the smallest possible voltage
drop.

The factors in the selection and design of input and output

leads differ, although the desired end-result is the same. The
input leads are always much longer than the output leads, but
the current is smaller and resistance (R) of the wire is the
principal consideration. The output leads must handle thousands
of amperes and the inductive reactance (XL) as well as the
resistance (R) must be considered.

TEST LEADS SUPPLIED WITH E.T.I. EQUIPMENT

INPUT LEADS The Model HC-50K/3 is supplied with a set of 20
foot input leads size 1/0.
The leads are terminated in heavy duty high
current connectors at the Test Set end. The
plugs will accept a range of wire more than
adequate for the duty required should it be
required to replace or extend the existing leads.

INPUT VOLTAGE The E.T.I. High Current Test Set is furnished for
operation at a specified input voltage at the
input terminals of the Test Set. This input must
be maintained under test conditions. The Test
Set will operate satisfactorily at 90-110% of
rated input voltage. The output voltage will
change proportionally to the change of the input
voltage.

OUTPUT For maximum output of the test unit, be sure that

adequate
CURRENT line voltage is available at the input terminals
of the Test Set under test conditions. In any
installations, it is necessary to use long input
leads to obtain power for the Test Set. The
leads should be heavy enough to prevent the input
voltage from decreasing more than 10% from the
nominal input value for which the Test Set is
designed. The current drawn from the power line
may be as much as 300% of the nameplate rating of
the Test Set when testing in the overload range.

OPERATING INSTRUCTIONS 7 MODEL: HC-50K/3

5. OUTPUT LEADS AND CONNECTIONS

The ideal situation is to use a test unit equipped with stabs to

accept the disconnect studs of draw-out breakers. When this
type of equipment cannot be used or the breaker is not of the
drawout type, there is no alternative but to provide leads from
the Test Set to the circuit breaker. The leads should be as
short as possible. When carrying currents of 5000 amperes or
more, each inch of additional lead can mean an appreciable
voltage drop which results in less current passing through the
breaker. The major drop comes from the inductive reactance of
the load circuit.

LENGTH OF LEADS
It is worthwhile to sacrifice cross section of test leads for
the sake of reducing length. Every inch of lead that can be
eliminated provides worthwhile increases in available test
current. Heating is not a problem in testing, even though the
leads become hot. The use of 4/0 welding or motion picture
cable is convenient for constructing test leads. Each 4/0 lead
can be rated to carry 600 amperes for testing long-time tripping
and 1000 amperes for testing instantaneous pickup. Paralleling
of sufficient cables provides a convenient setup for higher test
currents. Each cable may be fitted with a compression lug on
each end and bolted or soldered to a copper plate suitable for
clamping or bolting to the output terminals of the Test Set and
the breaker. When currents in excess of 10,000 amperes are
desired, the length of the test leads from the set to the
breaker should be kept to 6 inches or less. When longer leads
are unavoidable, twisted cable may be used. The two cables
between the Test Set and the breaker should be twisted together,
or at least bundled with tape or cord to maintain the close
proximity which minimizes the inductive reactance.
TYPES OF LEADS AND CONNECTIONS

The design of the output leads should be such as to minimize the

voltage drop between the Test Set and the load as much as
possible. Several of the available types of leads are as
follows:

1. STABS - Connect the load directly to the output terminals of

the Test Set with stabs.

2. COAXIAL CABLE - This type of cable has the lowest possible

voltage drop but is neither practical nor available for
these large currents.
3. BUSBARS - Buses in close proximity have good characteristics
but are physically unwieldy.

4. FLEXIBLE CABLE - When cables are made of extra flexible

welding cable, the result is a semi-flexible cable whose
impedance is reasonably low.

OPERATING INSTRUCTIONS 8 MODEL: HC-50K/3

OPERATING INSTRUCTIONS 9 MODEL: HC-50K/3
6. OPERATING INSTRUCTIONS

The MODEL HC-50K/3 HIGH CURRENT TEST SET is completely self-

contained and does not require any installation.
6.1. HOOK-UP

A set of high current leads, interconnecting cables and heavy

duty line input cables are provided with the instrument.
6.1.1. Interconnect the control unit with the high current unit and the
fine control with the multi-conductor cord and the heavy cables
provided. (see Interconnecting Details, Fig. 2)

6.1.2. Select a proper source of single phase 208 to 240, or 480 or 600
volts, 60 Hz. with a capability of 200 amperes minimum. MAKE
SURE THE SUPPLY HAS A PROPER GROUND!
6.1.3. Connect the heavy current leads to the Test Set and the line.
6.1.4. Connect the device to be tested to the proper terminals on the
Test Set via high current leads or stabs.
6.2. SELECTION OF COARSE and fine output terminals. The Test Set has
5 coarse terminals in steps of about 120 volts and 5 fine
terminals in steps of about 24 volts.

The fine control has an output of 0-24 V. This enables

continuous variation of input voltage to the highcurrent supply-
transformer and consequently continuous adjustment of output -
test current.
The output current depends on the load impedance and on the
setting of the output voltage to the high current transformer.
Proper settings will have to be established by trial and error
in the beginning and by experience of previous test settings.
Some rough guidelines are given in the output current - input
voltage table in section 7.
The Test Set can be used without the fine control if precise
current adjustment is not required.

Consult the approximate settings and vary the taps as required

by using the Test Set intermittently only in the MOM. mode.
6.3. TESTING IN THE MAINT. - C.A. MODE

The maintained - current - actuated mode (MAINT. - C.A.) is used

when testing series elements.

OPERATING INSTRUCTIONS 10 MODEL: HC-50K/3

6.3.1. Make sure the Test Set has been properly hooked up as described
in section 6.1. and 6.2.

6.3.2. Set the FUNCTION switch to the MAINT. C.A. position.

6.3.3. Select the proper range on the AMMETER.

6.3.4. Select the proper range on the VOLTMETER.

6.3.5. Make sure the output control on the fine control variable
transformer is at "0".

6.3.6. Throw the main breaker ON-OFF switch to ON.

6.3.7. Push the RESET button below the digital timer and hold until its
light is off.

6.3.8. The POWER light should be ON and the digital timer should read
000.000.
6.3.9. Push the START button and advance the current output control
until the AMMETER indicates the desired test current. The Test
Set will shut off and the timer will indicate the elapsed time
when the device under test opens and interrupts the current
flow.

NOTE: The Test Set will not seal-in at current less than 20%,
of full scale reading of the meter.
6.3.10. Should the Test Set have shut off prematurely or too much
time was taken up by current adjustments, proceed as follows:
a) DO NOT move the current adjustment.
b) Push the RESET button and hold until the light is off to
reset the Test Set and reset the timer to 000.000.
c) Push the START button.
d) The test current may decrease during the test, because of
the resistance or impedance of the test circuit increasing
as it heats up.
Trim the current control slightly to maintain the test
current at the desired level.
e) Record the test result.

6.3.11. The test can be interrupted as any time by simply pressing

the STOP button.

OPERATING INSTRUCTIONS 11 MODEL: HC-50K/3

6.4. TESTING IN THE MAINT. N.C. MODE

The maintained-normally-closed contact mode is used when testing

devices on which the opening of a contact is to be timed.

OPERATING INSTRUCTIONS 12 MODEL: HC-50K/3

6.4.1. Make sure the test sent has been properly hooked up as described
in section 6.1. and 6.2.

6.4.2. Set the FUNCTION switch to the MAINT. - N.C. position.

6.4.3. Connect the contacts to be monitored to the binding posts marked
CONTACTS.

6.4.4. Select the proper range on the AMMETER.

6.4.5. Select the proper range on the VOLTMETER.

6.4.6. Make sure the output control is at "0".

6.4.7. Throw the main breaker ON-OFF switch to ON.
6.4.8. Push the RESET button below the digital timer.

6.4.9. The POWER light should be ON and the digital timer should read
000.000.

6.4.10. Push the START pushbutton and advance the current output
control until the AMMETER indicates the desired test current.
The Test Set will shut off and the timer will indicate the
elapsed time as the "Normally - Closed" contact opens.

6.4.11. Should the Test Set have shut off prematurely or too much
time was taken up by current adjustment:
a) DO NOT move the current adjustment.
b) Push the RESET button and hold until its light is off to
reset the Test Set and reset the timer to 000.000.
c) Push the START button.
d) The test current may decrease during the test, because of
the resistance or impedance of the test circuit increasing
as it heats up. Trim the current control slightly to
maintain the test current at the desired level.
e) Record the test result.
6.4.12. The test can be interrupted at any time by simply pressing
the STOP button.

OPERATING INSTRUCTIONS 13 MODEL: HC-50K/3

6.5 TESTING IN THE MOMENTARY (MOM) MODE

The monetary mode is strictly used for set-up or short manual

testing. The Test Set will not seal in. Current will be
available only as long as the START button is held depressed.

OPERATING INSTRUCTIONS 14 MODEL: HC-50K/3

OPERATING INSTRUCTIONS 15 MODEL: HC-50K/3
7. TAP SETTINGS

The tapped auto-transformer provides 5 course (120V step) taps

and 5 fine
(24 V steps) taps. This makes it possible to select any output
voltage from 0V to 600V in 24 volt steps. (Even finer
adjustment is achieved by the "fine-control" section.)

An example: See Fig. 3 Coarse and fine taps

To select 24V - insert blue in OV yellow in 24V

To select 72V - insert blue in OV yellow in 72V

To select 168V - insert blue in 72V yellow in 240V
To select 360V - insert blue in 0V yellow in 360V

Due to the variation in impedance of the breakers under test, it

is impossible to define output voltages without trial.

Experience and a well kept log will help in future selections.

The following are some rough guidelines:

Output TAP Fine Control

Required Settings

0 - 1000A 24V "Bucking" blue leads

reversed
0 - 2500A 24V
NORMAL
0 - 4000A 48V
NORMAL
0 - 5000A 72V
NORMAL
0 - 10000A 120V or
higher NORMAL
0 - 25000A
240V or NORMAL
higher

Other combinations can be chosen, the above are guidelines only.

ALWAYS START AT A LOWER SETTING IF IN DOUBT.

OPERATING INSTRUCTIONS 16 MODEL: HC-50K/3

8. TEST PROCEDURES

8.1. LOW VOLTAGE POWER CIRCUIT BREAKERS

Discussion:
The practice of testing low voltage power circuit breakers
equipped with series-trip units is increasing. Because many
circuit breakers have failed to trip on faults, there is a
growing awareness that they require testing. These failures may
be caused by improper application, lack of maintenance, or
incorrect settings. Low voltage power circuit breakers require
more attention than occasional dressing of contacts and manual
tripping. While many defects such as loose connections and
faulty components are found by visual inspection and manual
handling of the breakers, a complete over-all test at high
currents is necessary to determine that the breaker is in
operable condition and will trip within the desired limits.
Characteristics - The low voltage power circuit breaker has wide
application and may be used to protect circuits up to 600 volts
A.C. or 250 volts D.C. When used as a direct acting circuit
breaker, a dashpot (oil or air) or a mechanical escapement
mechanism is generally utilized to provide time delay before
tripping.

These circuit breakers are available with several kinds of

closing and tripping devices as shown below:
1. Manual Closing - Breaker is mechanically closed by the
operator with a handle or lever. Often the mechanical
closing device employs a loaded spring to assure rapid
closing of the contacts.
2. Electrical Closing - Breaker employs a solenoid or small
motor together with mechanical linkage. This breaker may be
closed from a remote location.

3. Protective Relay Trip - A protective relay may be used to

initiate a trip through a solenoid trip coil and an external
source of power. With this type of trip, closer co-
ordination is possible.

4. Series Trip - The direct acting series trip device actually

carries the load current and normally employs the principle
of electro-magnetic attraction of the plunger or armature.
The magnetic attraction is opposed by the action of a
dashpot to get time delay operation or a spring to get
instantaneous operation. The tripping characteristics of
these devices is a relatively wide time band.

5. Direct Acting Trip from a Current Transformer - The

principle of operation is the same as the Series Trip except
that the trip coil receives its energy from the secondary of
a current transformer located in the power circuit.

OPERATING INSTRUCTIONS 17 MODEL: HC-50K/3

 6. Static Trip Types - Several manufacturers offer low voltage
power circuit breakers with solid state sensors providing
the same function as the simple series trip devices but
having greater sensitivity and repeatability.
NOTE: When testing static trip breakers which are fitted
with ground sensing circuitry, the ground trip function must
be blocked in order to test phase pick-up and timing.
Consult manufacturer's instruction book.

PRINCIPLE OF OPERATION - Series Trip - Direct acting low voltage

power circuit breakers are tripped by the movement of an
armature which strikes the trip bar of the breaker. The trip
bar operates a latch which releases stored energy attracted to a
pole piece through the magnetic field set up by current flow
through a coil. The current which flows through the coil is
either the primary load current or the output of a current
transformer (usually 5 amperes). The armature is restrained
mechanically to achieve the desired pickup and tripping time.
Tripping time is a function of quantity of current through the
breaker.
Manufacturers of low voltage power circuit breakers indicate
that approximately 90% of all breakers contain a dual-element
trip unit which provides long-time delay and instantaneous trip
characteristics. Selection of the proper trip unit depends upon
the nature of the circuit to be protected, the degree of
sensitivity desired, and other protective devices with which the
trip unit must co-ordinate.

The long-time delay is usually accomplished by means of a

dashpot in which a piston with a restrictive orifice is pulled
(or pushed) through a cylinder containing fluid. The piston
speed is a function of the magnetic force imparted to the
armature, the size of the orifice and viscosity of the fluid.
Time delays of 10 to 60 seconds at 300% of pickup are common in
this type of trip.
The short-time delay mechanism may be either an escapement or a
dashpot. Tripping time from 2 to 30 cycles may be realized at
500 to 1000 per cent of trip coil rating.

The instantaneous trip is generally calibrated by a spring on a

lead screw. The instantaneous trip overrides the dashpot and
operates against a calibrated spring. An instantaneous trip is
built with no intentional time delay.
Setting of Series Trips - Trip units are tested and calibrated
at the factory by the manufacturer. Calibration plates are
affixed on which are stamped the calibration points. The plate
may be marked in either percentage of coil rating or amperes.
The calibration points vary with manufacturers and application.
The NEMA standard calibration on the long-time trip is 80, 100,
120, 140, and 160 per cent of coil rating. Thus, a 600-ampere
coil may be field adjusted between 480 and 960 amperes pick-up
current. However, this coil cannot be used for continuous loads
in excess of 600 amperes.

OPERATING INSTRUCTIONS 18 MODEL: HC-50K/3

 On most breakers, the short-time and instantaneous pickup values
are adjustable. It should be kept in mind that the short-time
and instantaneous elements are always multiples of the 100%
setting (coil rating). In setting these pickup values, care
should be exercised to make sure that the adjustment pointer is
set on the proper calibration mark and not necessarily opposite
the printed numerals.

In addition to these adjustments, some manufacturers provide an

adjustment of the time band in which the entire band may be
shifted. It is important that the proper interpretation of the
manufacturer's time current curves be made.

Common Causes of Malfunction - Malfunction of the low voltage

power circuit breaker may be the result of any of the following:
1. Improper main contact pressure resulting in local
overheating and burning of contact surfaces. In extreme
cases, contacts may actually be welded together through this
local overheating. Deterioration of insulation may result.

2. Improper fit of breaker primary fingers on the bus stabs.

Once again, local overheating would result and ruin tension
in the primary finger springs.
3. Cracked or dirty arc chutes could cause a phase-to-phase or
phase-to-ground flashover when the breaker is operated under
load.
4. Stiff or frozen mechanical joints in either the breaker
mechanism or trip device mechanism may cause delayed
operation or no operation.
5. Vibration may cause a shifting of the trip bar so that the
armature of the overload device fails to strike "home".
Thus, the latch would not be released to trip the breaker on
overload.

6. Worn parts or loss of oil in the overload device dashpot.

7. Contaminated oil in the overload device dashpot freezing the
armature action, resulting in failure of the breaker to
trip.

8. Improper calibration or setting of the overload trip device.

Of all possible faults, it is considered that improper delay

in opening automatically under overload conditions is the
most dangerous. Normal operational procedures and careful
maintenance inspections will reveal most of the other
conditions that are likely to remove protection from the
circuit. Unless overload tests are run, there is no way
that a circuit breaker having improper delay will become
apparent until it is actually needed for circuit protection
- and then it is too late.

OPERATING INSTRUCTIONS 19 MODEL: HC-50K/3

 PLANNED MAINTENANCE PROGRAM

General Considerations

A. PLAN
Set up a circuit breaker test program to fit your system's
needs.

B. TRAIN
The program should include instruction to personnel in the
basic purposes and principles of circuit breaker operation
as well as the "how" of circuit breaker testing with modern
equipment. (see enclosed pamphlet). Ferguson-Brosz is
available for this training.
C. SCHEDULE
The test program should be set up on a regular schedule.
Test periods will vary with individual needs.
Scheduling is most important because it is necessary to de-
energize a circuit before maintenance can be performed on
the breaker. If the breaker to be maintained is of the
draw-out type and a spare breaker of the same frame size and
rating is available, this period of shutdown may be short
(just long enough to clean the cubicle and switch the
breakers). On the other hand, if the breaker is permanently
mounted, sufficient time must be allowed to unbolt the
breaker from the bus.
D. READ AND UNDERSTAND MANUFACTURER'S INSTRUCTION LITERATURE
The first step in setting up a test program is to determine
the results to be sought. In order to accomplish this, a
thorough knowledge of the device to be tested is necessary.
The manufacturer's literature should be consulted for
familiarization with the device and the performance expected
of it.
E. SAFETY MEASURES
Test personnel should be familiar with the "shock hazard".
Electrical Testing Instruments Ltd., equipment is as nearly
shock-free as possible. In addition to the normal hazards
associated with working around electrical circuits, many low
voltage power circuit breakers contain stored energy devices
and care must be exercised to avoid mashed fingers.
F. NEATNESS
Careless setups can waste valuable time and often result in
erroneous data.

G. ELECTRIC POWER REQUIREMENTS

Make sure input facilities are available to match the
nameplate data on the test equipment and suitable outlets
for drop lights, power tools and other test equipment.

OPERATING INSTRUCTIONS 20 MODEL: HC-50K/3

 H. PROPER TOOLS
Be sure proper tools and any special wrenches or leads are
available at the job site.

I. SWITCHGEAR SPARE PARTS

An adequate supply of the proper dashpot oil and lubricants
should be on hand. Hardware, contacts and other replaceable
components should be available at the job site.

J. RECORD
Good records are very important. An individual test sheet
for each circuit breaker is recommended. This is the only
way to determine the economical frequency of planned
maintenance. A suggested record form is included in the
rear of this section.
TYPICAL MAINTENANCE PROGRAM

A typical maintenance program for testing of low voltage power

circuit breakers in the field is as follows:

1. Routine examination, cleaning and lubrication of mechanical

parts.
2. Inspection, dressing and/or replacement and alignment of
main and arcing contacts.

3. Examination of the setting of the trip units.

4. Electrical testing to determine if the tripping times fall
within acceptable limits.

Visual and Mechanical Inspection

A planned maintenance visual and mechanical inspection of a low
voltage power circuit breaker includes the following:
1. Trip breaker and "rack-out". With the breaker in the
"racked-out" position, make sure that the breaker contacts
cannot be closed. This is a safety feature and assures that
the breaker cannot be restored to the operating position
with the main contacts closed.

2. Completely remove breaker from cubicle.

3. Using extreme care, clean the cubicle of dust, dirt, loose
hardware etc. Remember that the bus (line) side stabs in
the cubicle may still be "hot". In a tie breaker, both sets
of stabs in the cubicle may still be "hot".

OPERATING INSTRUCTIONS 21 MODEL: HC-50K/3

 4. Lubricate the tracks, jack screws or other mechanism present
in the cubicle for racking the breaker. See manufacturer's
recommendations for type of lubricant.

5. Cover the opening to the cubicle if spare breaker is not

available.

6. Clean the breaker.

7. Examine the primary fingers on the breaker for evidence of

overheating or embrittlement cracks. Check springs for
tension. Clean and service finger contact surfaces are
required.
8. Remove arc chutes, examine for cracks, dirt, splashed
copper, broken or cracked snuffers. Clean.

9. Examine both main and arcing contacts of the breaker. If

worn or badly pitted, dress as required (see manufacturer's
instructions). Adjust racking device so that contacts may
be manually closed. KEEP FINGERS AND OTHER PARTS OF THE
BODY AWAY FROM THE CONTACTS.
Manually close contacts and observe that all three phases
make at the same time; also, that the arcing contacts (if
fitted) make first on closing and break last on opening.
Make suitable adjustment.

10. With the breaker contacts open, insert a piece of paper

backed with carbon paper between the fixed and moving
contacts; close breaker, then manually trip breaker. Remove
paper and examine the "contact print" to make sure both
moving and fixed contacts are mating properly. Check proper
operation of counter and/or flag.
11. Tighten all screwed and bolted connections except pivot
joints.
12. Make sure that the armatures from all trip devices strike
the trip bar to trip the breaker.
13. Manually operate the armature of undervoltage and shunt
armatures and make sure they strike the trip bar and trip
the breaker.
14. Lubricate mechanical joints and the racking device. Follow
manufacturer's recommendations on choice of lubricant. Keep
lubricants away from electrical contact surfaces.

15. Examine all overload trip devices to verify that they are
all the same type, have the same rating, and have proper
setting.

OPERATING INSTRUCTIONS 22 MODEL: HC-50K/3

 ELECTRICAL TESTING - DISCUSSION

Because 90% of all low voltage power circuit breakers

manufactured contain the long-time delay and instantaneous trip
characteristics combination, a discussion of a typical test
program covers these units.

Most of these breakers are equipped with one series overcurrent

trip device per phase. The operation of any one of these
devices will trip the breaker.
In testing a low voltage power circuit breaker equipped with
series OVERCURRENT trip devices, several points must be
remembered.
A. The values of test current are high and the voltage low.
Therefore, it is advisable to use the shortest connections
with the largest possible cross sections between the test
unit and breaker. In some cases, pieces of busbar are used
for these connections. (see section "Output Leads and
Connections"). The larger Electrical Testing Instruments'
circuit breaker test units are provided with adjustable
stabs which fit most modern low voltage power circuit
breakers.
B. The connection to the primary fingers of the breaker must be
tight.

C. The breaker is tested one phase at a time.

D. Trip devices must be allowed to fully reset between tests.
INTERPRETATION OF TEST RESULTS - It has been pointed out that
the allowable tripping band of the long time delay is quite
wide. The same breaker tested in the same manner and with the
same test equipment may give varying results when tested at
different times because of the effect of temperature and
vibration. Therefore, it is generally considered impractical to
attempt to obtain a precise tripping time on a given test. For
example, on a long time delay test, where the allowable band is
10 to 32 seconds, much time can be wasted trying to adjust this
unit for exactly 18 seconds tripping time. The device should be
tested to assure that it performs the intended function for that
particular application, assuming that such performance is within
the manufacturer's statement of capability. The intended
function may allow considerable leeway in timing. A breaker may
trip in less than the time specified in the manufacturer's
specifications and still perform its function.
Original factory tolerance varies with manufacturers from 10% to
20%. Therefore a value within 10% to 20% on the instantaneous
or short-time pickup is satisfactory. It should be remembered
that the manufacturer's calibration point on the trip unit is
based on a current wave containing no D.C. offset. In many
applications, there may be considerable D.C. offset in fault
current. Therefore, time spent trying to get a precise
adjustment is unjustified.

OPERATING INSTRUCTIONS 23 MODEL: HC-50K/3

 RECOMMENDED TESTS

1. Timing - Long and/or short-time delay elements.

Suggested test point is 3% trip unit setting for long time

delay and 1.5X trip unit setting for short-time delay.

2. Pickup - Instantaneous Element.

Test for minimum pickup current. Do not time.

TESTING TIME DELAY

1. Refer to the manufacturer's literature for Time Current

Curves of the device to be tested.
2. Connect the High Current test set to a suitable source of
power as indicated on the nameplate, and ground. CHECK THE
INPUT VOLTAGE. BE SURE THE MAIN SWITCH IS OFF.
3. Connect the main test leads to the pole of the device to be
tested.
4. Connect "Relay Contacts" binding posts of the Test Set to
another pole of the circuit breaker under test.

5. Turn fine control to zero (extreme counter-clockwise stop).

6. Turn "Power On" switch ON. "Power On" light should glow.
7. Select proper ammeter range. Pre-set ammeter using Pointer
Pre-set to 1/8 inch down scale. (See "Current Metering
Circuit").
8. Close breaker under test.

9. With Timer Selector Switch is "MOM" position, jog unit with

the test pushbutton while slowly rotating Fine Control
clockwise to increase output until required current is
reached. If, at full rotation of the Fine Control the
desired current is not obtained, return Fine Control to zero
setting and select the next higher voltage tap. (See
"Output Tap Selection"). 6.2

10. Reset timer to zero. Switch "Timer Selector" switch to

"MAINT. N.C." position.

11. Allow time for thermal, hydraulic or other actuating devices

to reset.
12. Press initiating START pushbutton. (See Note).

OPERATING INSTRUCTIONS 24 MODEL: HC-50K/3

 13. Timer will stop and unit will de-energize when device under
test trips.

14. When test is completed, read timer. Time indicated on the

face of the timer is the total operating time.
15. Record results and check against manufacturer's
specifications.

16. Return Control to zero and tap to zero.

NOTE: Return ammeter pointer Pre-set to zero and check
ammeter while test is on for accurate reading. Minor
adjustment may be made with main Control during the running
of the test.
TESTING INSTANTANEOUS PICKUP

It has been explained previously that the instantaneous pickup

of the trip unit is set by varying the tension on a calibrated
spring with an adjustable screw. It should be noted that unless
the purchaser of a circuit breaker specifies otherwise, a
breaker will be shipped from the factory with the instantaneous
element set at maximum. Therefore, the need for the
instantaneous element setting at or near maximum should be
questioned.

Testing the instantaneous trip on larger circuit breakers set at

or near maximum calibration may demand purchase of a much larger
test set than would otherwise be necessary. In most cases, the
instantaneous unit has several calibration marks between 600%
and 1500% of the continuous rating of its coil. Testing at one
of the lower calibration marks is satisfactory. The lead screw
may be set to the lowest calibration point (600% on most units)
and tests made at that point to verify that the unit will pick
up. If the instantaneous unit picks up at the minimum
calibration point, it may be reasonably assumed that, when reset
to the desired calibration point, pickup will be within
manufacturer's tolerances. This has been verified by the
manufacturers and by field tests.
By definition, the instantaneous elements has no intentional
time delay. Therefore, no attempt should be made to time the
operation of this device in the field.

The pickup point of the instantaneous element is subject to

several variables; most manufacturers apply ± 20% tolerance.
When testing instantaneous pickup, it is necessary to first
determine the minimum setting on the Fine Control (variable
auto-transformer) at which the breaker consistently trips
instantaneously. It should be remembered that the test current
will flow for only a fraction of a second and, therefore, a
special technique is necessary to determine the value of this
current. The breaker should be tripped several times at the
previously determined setting of the Main Control and the
current read on the ammeter. The proper reading is at the point
where the ammeter needle just quivers against the pre-set arm.
The following procedures is suggested:

OPERATING INSTRUCTIONS 25 MODEL: HC-50K/3

 TEST PROCEDURE FOR INSTANTANEOUS PICKUP

1. Always refer to manufacturer's literature before testing.

2. Connect the High Current Test Set to a suitable source of

power as indicated on the name-plate, and ground. BE SURE
THE MAIN SWITCH IS OFF.

3. Connect the high current terminals to the circuit breaker

under test. (See "Selection of Output Taps" and "Input and
Output Leads").

4. Set Function Switch to MOM.

5. Connect "Relay Contacts" binding posts of Test Set to
another pole of the circuit under test.

6. Set Main Control counterclockwise to zero.

7. Set "Ammeter Range" Switch to appropriate range for current
to be measured.
8. Close circuit breaker under test.
9. Slowly rotate Fine Control clockwise while "jogging" the
START pushbutton until the circuit breaker under test trips
instantaneously. Observe taps and Fine Control reading at
this point.
NOTE: An instantaneous trip is one where the breaker under
test audibly appears to trip simultaneously with the
depressing of the initiate pushbutton of the Test Set.

8.2 OPERATIONAL CHARACTERISTICS OF TESTING MOLDED CASE CIRCUIT

BREAKERS

The test operator should be familiar with the operating

characteristics of the circuit breaker, the tolerances
applicable to the operating characteristics and the means for
adjusting the circuit breaker, if any. Reference to the
manufacturer's literature on the circuit breaker to be tested
should be made prior to testing.

The purpose of the test on circuit breakers is to ascertain the

actual reaction time delay, under overload conditions, in
comparison with the manufacturer's data on the time-current
curve. One test point is usually suggested to establish whether
the relay is operating correctly and within the parameters of
the time-current curve for the circuit breaker. The suggested
test current is three times (3X) the normal current rating of
the circuit breaker.

OPERATING INSTRUCTIONS 26 MODEL: HC-50K/3

 It is easier to make connections and perform the test on circuit
breakers if they are removed from the circuit. However, it is
not necessary to remove the circuit breaker, as long as the test
leads can be connected and the line side of the breaker is de-
energized. It should be further noted that any leads already
connected to the circuit breaker need not be removed when
conducting the test. The high current leads from the Test Set
to the circuit breaker under test, should be kept as short as
possible and should be twisted to minimize the losses caused by
inductive reactance.
Run the test and note the time required for the circuit breaker
to trip. If the tripping time exceeds the desired value, or if
the circuit breaker does not trip at all, the circuit breaker
may not be protecting the circuit properly. If the circuit
breaker operates too quickly, it may result in unnecessary
nuisance trips. It should be remembered that molded case
circuit breakers operate within a wide time band. Therefore,
precise results should not be sought and, if the circuit breaker
trips within the time band, it is considered satisfactory. A
tolerance of ± 115% is usually acceptable. Look for the circuit
breaker that has usually short-time delay, or takes an
abnormally long time to trip, or does not trip at all. In the
latter case, electrically operating and thereby exercising the
breaker, may correct the condition.

8.3 OPERATIONAL CHARACTERISTICS OF TESTING MOTOR OVERLOAD RELAYS

The test operator should be familiar with the operating

characteristics of the relay, the tolerances applicable to the
operating characteristics and the means of adjusting the relay,
if any. Reference to the manufacturer's literature on the
overload relay to be tested should be made prior to testing.
The purpose of the test on overload relays is to ascertain the
actual reaction time delay under overload conditions, in
comparison with the manufacturer's data on the time-current
curve. One test point is usually suggested to establish whether
the relay is operating correctly and within the parameters of
the time-current curve for the relay. The suggested test
current is three times (3X) the normal current rating of thermal
overload relays or three times (3X) the pickup current (setting)
of the magnetic overload relays.

It is easier to make connections and perform the test on the

relays if they are removed from the starter. However, it is not
necessary to remove the relay as long as the test leads can be
connected and the circuit de-energized. It should be further
noted that any leads already connected to the relay need not be
removed when conducting the tests. The high current leads from
the Test Set to the relay under tests. The high current leads
from the Test Set to the relay under test should be kept as
short as possible and should be twisted to minimize the losses
caused by inductive reactance.

OPERATING INSTRUCTIONS 27 MODEL: HC-50K/3

 Run the test and note the time required for the overload relay
to trip. If the tripping time exeeds the desired value, or if
the relay does not trip at all, the relay may not be protecting
the motor properly. If the relay operates too quickly, it may
result in unnecessary nuisance trips. It should be remembered
that these devices operate over a wide time band and precise
results should not be sought. A tolerance of ± 15% is usually
acceptable.

If a thermal overload relay is not operating properly, tripping

too soon or too late, remove the heater element. Note its type,
rating, etc., and compare with manufacturer's data for operating
characteristics of the motor. If correct for the application,
substitute a new heater of the same rating and retest. if
improper heater size is being used, either undersized or
oversized, replace with proper size heater and retest.

If a magnetic overload relay is not operating properly, refer to

the relay manufacturer's literature for instructions on making
adjustments to the time delay. If the relay is operating
improperly, it may also be desirable to verify the pickup point
(minimum operating point), of the relay. To perform this test
it is necessary to disengage the time delay feature of the
overload relay. Refer to manufacturer's literature for detailed
instructions.

It is important to remember that in order to obtain accurate

tripping times within same types of magnetic overload relays,
particularly those using high viscosity dashpot oil, it may be
necessary to "preheat" the relay by running rated current
through the relay for a few minutes.

OPERATING INSTRUCTIONS 28 MODEL: HC-50K/3