AVO CB-845X User manual

Part _ S/O 81892
Rev. 0
INSTRUCTION MANUAL
For
CIRCUIT BREAKER
TEST SET
MODEL CB-845X
It is essential that this instruction book be read thoroughly before putting the

Part _ S/O 81892
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equipment in service.
IMPORTANT
The information and data contained within this instruction manual are proprietary with AVO
MULTI-AMP Corporation. The equipment described herein may be protected by one or more
U.S. letters patent. AVO MULTI-AMP specifically reserves to itself all rights to such
proprietary information as well as all rights under any such patent, none of which is waived by
the submission of this instruction manual to anyone.
The recipient, if a Government agency, acknowledges that this instruction book and the
equipment described were procured with "Limited Rights" to technical data as described in
ASPR 9-203 (b).

Part _ S/O 81892
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Copyright AVO MULTI-AMP Corporation, 1993
TABLE OF CONTENTS
I. General Information Page
A. General Description 1
B. Common Test Applications 1
C. Specifications 1
D. Description of Features 3
E. Operational Safety 6
F. Input Circuit 6
G. Selection of Input Leads 7
H. Output Circuit 8
I. Selection of Output Leads 8
J. Overload Capacity 9
II. Test Procedures
A. Time Delay Test - Motor Overload Relays 10
B. Instantaneous Test - Motor Overload Relays 11
C. Time Delay Test - Molded Case Circuit Breakers 13
D. Instantaneous Test - Molded Case Circuit Breakers 14
E. Trip Test - Ground Fault Interrupters 15
III. Maintenance Procedures
A. Maintenance of Molded Case Circuit Breakers 17
B. Maintenance of Motor Overload Relays 18
IV. Model CB-845X Maintenance
A. General Maintenance Procedures 21

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B. SRO Instructions 22
C. CB-845X Parts List 23
D. Warranty Statement 25

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GENERAL DESCRIPTION
The Multi-Amp Model CB-845X Circuit Breaker Test Set is a self-contained unit which
provides a continuously adjustable high current output and incorporates a digital
ammeter, digital timer and control circuitry. The test set consists of two units housed in
interlocking, stackable, rugged, metal enclosures. Each unit has convenient carrying
handles for easy portability.
COMMON TEST APPLICATIONS
Multi-Amp Model CB-845X is specially designed to provide high current at sufficiently
high voltage for testing ground grids or high impedance circuit breakers.
The Model CB-845X is suitable for a wide variety of testing requirements including
molded case circuit breakers, thermal, magnetic or solid-state motor overload relays
and other overcurrent protective devices. Additional applications include ratioing
recurrent transformers and testing ground fault trip devices.
SPECIFICATIONS
Input (switch-selected): 208 and 240 volts, sin
g
le-phase, 60 hz. + 5%
Output Ran
g
e: The output is continuousl
y
ad
j
ustable throu
g
h 7
ranges to meet a wide variety of test circuit
impedances.
0-5.5 volts at 1000 amperes
0-11 volts at 500 amperes
0-22 volts at 250 amperes
0-44 volts at 125 amperes
0-88 volts at 62 amperes
0-176 volts at 31 amperes
0-350 volts at 15 amperes
Ammeter: A solid-state di
g
ital instrument with a 0.3" (7.62
mm) LED 3 1/2 digit display.
Ran
g
es (switch selected): 0-19.99/199.9/1999 amperes/10.00 kiloamperes
Accurac
y
(overall ammeter
system):
+ 1% of readin
g
+ 1 di
g
it for 0-199.9/1999 amperes-
/10.00 kiloamperes ranges.
+1% of range + 1 digit for 0-19.99 amperes range
Modes (switch-selected):
Memor
y
: Read-and-hold memor
y
feature retains current

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readin
g
after one complete c
y
cle.
Normal: Continuall
y
updates ammeter readin
g
as current
changes.
Timer: A solid-state cr
y
stal controlled di
g
ital timer with
0.3" (7.62 mm) LED 5 digit display.
Seconds Mode:
Ranges: 0-99.999 seconds
0-999.99 seconds
Accurac
y
: + .005% of readin
g
+ 1 di
g
it
C
y
cles Mode:
Ran
g
e: 0-99999 c
y
cles
Accurac
y
: + .005% of readin
g
+ 1 c
y
cle
Output Capacit
y
: Where the output volta
g
e is sufficient to "push"
higher than rated current through the impedance of
the load circuit, the test set may be overload for
short durations as shown below.
PERCENT
RATED CURRENT
MAXIMUM
TIME ON
MINIMUM
TIME OFF
100% 30 minutes 30 minutes
200% 75 seconds
6 minutes
300% 25 seconds
4 minutes
Protectio
n
: Overload and short circuit protection is
incorporated.
Housin
g
: Hi
g
h stren
g
th, metal enclosures with eas
y
-to-carr
y
handles.
Dimensions:

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Control Unit - Hei
g
ht: 11 1/4 inches
Width: 21 inches
Depth: 17 1/2 inches
Output Unit - Hei
g
ht: 11 1/4 inches
Width: 21 inches
Depth: 19 1/2 inches

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Wei
g
ht:
Control Unit: 89 1/4 pounds
Output Unit: 205 pounds
Complete Unit: 294 pounds
Test Leads: Two No.22 timer leads each 5 feet (1.5 m) lon
g
.
These leads are used to connect the binding posts on
the CB-845X labeled CONTACTS to the contacts of
the device under test which will open or close when
the device operates. Two No. 4 high current leads,
each 5 feet (1.5 m) long and two No. 4/0 high
current leads, each 4 feet (1.2 m) long.
Interconnect Cable: Standard cable supplied to interconnect the control
and output units is 4 feet (1.2 m) long. An optional
cable 10 feet (3m) in length is also available.
DESCRIPTION OF FEATURES
NOTE: For greatest accuracy, allow 15 minutes for instrumentation warm-up.
POWER ON/OFF
SWITCH:
Molded case circuit breaker resets after an overload
when placed in the OFF position. Displays will light
up when the switch is turned on.
INPUT VOLTAGE
SELECTOR SWITCH:
Selects volta
g
e settin
g
to match volta
g
e source.
WARNING: SELECT PROPER VOLTAGE BEFORE TURNING POWER SWITCH
ON.
MAIN FUSE: Protects power output circuit of unit a
g
ainst
overloads.
CONTROL FUSE: Protects instrumentation and control circuitr
y
against overloads.
NOTE: Replace fuses with the same size and type as those supplied with test set.

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OUTPUT CONTROL: Variable autotransformer provides continuous no
n
-
stepped output from a variety of current terminals.
Output system is controlled by a combination of
timer STOP MODE and OUTPUT MODE Switch
positions.
AMMETER: LED displa
y
shows the numeral one in the left-most
digit when the meter is over-ranged.
RANGE SWITCH: Decimal of displa
y
shifts one di
g
it to the ri
g
ht for
each increase in range selection. Decimal moves to
two digits from right on highest range.
DISPLAY MODES: Switch selectable for NORMAL or MEMORY.
MEMORY: Retains hi
g
hest readin
g
attained durin
g
current
output operation above 8% of full scale of range
selected. Reading is retained until the unit is
reintiated or RANGE Switch position is changed.
NORMAL: Updates readin
g
s continuall
y
as lon
g
as output is
energized. Reading is lost when output is de-
energized.
TIMER: Automaticall
y
resets each time the unit is initiated.
DISPLAY MODES: Switch selectable for c
y
cles or seconds.
CYCLES: Reads in whole c
y
cles.
SECONDS: Two switch selectable scales of either two or three
decimal places.
NOTE: Changing display mode or scale during operation will produce erroneous
readings.
STOP MODES: Switch selected for external contact position or
current actuate.
NORM. OPEN: With CONTACTS bindin
g
posts connected to
normally open external contacts, output will remain
energized and timer will continue to run until
contacts close.

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NORM. CLOSED: With CONTACTS bindin
g
posts connected to
normally closed external contacts, output will
remain energized and timer will continue to run
until contacts open.
CURRENT: Timer will initiate onl
y
when output circuit is
completed and threshold current of approximately
8% of full scale of ammeter range selected is
exceeded. Timer will continue to run until output
circuit opens, drops below threshold level, or is de-
energized.
NOTE: Current must be maintained above threshold level or timer error will
result.
CONTACT BINDING
POSTS:
Circuit controls output and timer in the normall
y
open/closed stop modes when connected to external
contacts.
WARNING: DO NOT CONNECT CONTACTS BINDING POSTS TO AN
ENERGIZED CIRCUIT.
OUTPUT MODE SWITCH: Initiates output circuit in con
j
unction with
appropriate timer STOP MODE position.
OFF: Unit remains powered up but the output is de-
energized and the timer will not run.
MOMENTARY: Momentar
y
"ON" position with sprin
g
return to
center OFF. Output will remain energized as long
as the switch is held in MOM. position and is de-
energized when released. Timer starts and stops in
the same manner.. Used for "jogging" output the
circuit.
MAINTAIN: Switch ener
g
ized output circuit when moved to
MAIN. position. Output will remain energized until
appropriate STOP MODE function occurs, switch is
moved to OFF or current drops below threshold
requirement of control circuitry.
OUTPUT INDICATING
LAMP:
Li
g
hts up whenever output circuit is ener
g
ized.

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OPERATIONAL SAFETY
Every consideration has been given to the design and construction of the Model CB-
845X Test Set to make it a safe piece of test equipment as well as one that is accurate,
reliable, and easy to use.
It must be remembered that the unit is capable of producing high voltage and current
levels that can be deadly if personnel came in contact weigh them.
When stacking units, make sure feet of the top unit are firmly seated in the depressions
in the top of the bottom unit. If the output unit is elevated to get it closer to the device
under test, be sure it is secured on a sturdy platform.
For maximum safety of unit operation, the power cord should be connected to a
properly grounded power supply receptacle.
Always de-energize the test set before handling any of the output terminals, moving
test leads or changing connections on the test set or device under test.
Never connect the unit outputs or test circuits to a device to be tested that is energized.
Protect the unit from rain, water, oil, or any substance that could cause an electrical
hazard or damage the unit. Do not set the unit in water or use it in wet areas.
The CB-845X should be properly operated and serviced by qualified individuals who
have familiarized themselves with the unit and thoroughly read the instruction manual
provided with it.
If questions arise concerning care, operation, or application of the unit that are not
explained in the instruction manual, contact a Multi-Amp Corporation representative.
INPUT CIRCUIT
INPUT VOLTAGE:
The Multi-Amp CB-845X Circuit Breaker Test Set is designed to operate on a single
phase 208 or 240 volt input. The selector switch on the front of the unit is used to select
the input voltage tap that matches either 208 or 240 volt power supply available.
INPUT CONNECTIONS:
Due to the wide variation in individual user requirements with regard to wire sizes,
terminations and length of leads, all units are supplied with input socket and matching
plug only. The plug will accept a wide range of wire sizes more than adequate for the
duty required. The power source must have sufficient capacity, and the input leads
must be large enough to maintain RATED input voltage at the INPUT terminals of the

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test set. Although the test sets are designed to operate satisfactorily at 95-105% of rated
voltage, any drop in voltage below RATED at the input terminals will result in a
proportional decrease in the maximum available output.

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NOTE: To achieve published output currents, the rated input voltage must be
maintained at the test set terminals during the test.
GROUNDING:
A grounding terminal is provided in the input plug to match that provided in the input
socket. A properly connected ground wire contained in the input cable selected should
be connected to a properly grounded power supply receptacle.
SAFETY GROUND:
If an extra measure of safety is desired, a ground wire can be connected externally of
the input power cord and connector. The size of this conductor should not be less than
1/2 the cross section of the current carrying input leads (three wire sizes less) and in no
event smaller than #10. This wire should be securely connected to the enclosure of the
test set (preferably the control section) and to an approved ground.
SELECTION OF INPUT LEADS
INPUT LEADS:
When utilizing maximum output from the test set, the input line currents may be as
high as 400% of nameplate rating. The following table has been prepared to aid in
selecting the proper wire size for the input leads. To use the table, follow the four steps
that follow:
1. Determine the rated input current from the nameplate on the test set. Be
sure to choose the correct current for the input voltage being used.
2. Multiply this value by four.
3. Determine the length of the input lead required. This is in circuit-feet,
therefore, it is the one-way distance from the test set to the power source.
4. Select the proper wire size from the table using factors 2 and 3 above.
Example: Step 1 - 30 amperes (from input circuit breaker rating)
Step 2 - 4 x 30 = 120 amperes
Step 3 - 80 ft. (distance from test set control section to input
power source)
Step 4 - # 6 wire (from chart)

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SELECTOR CHART FOR INPUT LEADS
LENGTH OF INPUT LEADS
DISTANCE FROM TEST SET TO POWER SOURCE
FEET
FOUR (4X) TIMES
RATED INPUT CURRENT 20 40 60 80 100 120 140
50 8 8 8 8 8 8 8
75 8 8 8 8 8 8 6
100 8 8 8 8 6 6 4
125 8 8 8 6 6 4 4
150 8 8 8 6 4 4 2
175 8 8 6 4 4 2 2
200 8 8 6 4 4 2 2
225 8 8 6 4 2 2 1
250 8 6 4 4 2 2 1
275 8 6 4 2 2 1 1/0
300 8 6 4 2 2 1 1/0
325 8 6 4 2 1 1 2/0
350 8 4 2 2 1 1/0 2/0
375 8 4 2 2 1/0 2/0 2/0
400 8 4 2 1 1/0 2/0
425 8 4 2 1 1/0 2/0
450 8 4 2 1 2/0
475 6 4 2 1/0 2/0
500 6 4 2 1/0 2/0
525 6 2 1 1/0 2/0
550 6 2 1 1/0
575 6 2 1 2/0
600 6 2 1 2/0
The wire sizes in this chart will result in voltage drops of ten volts or less.
OUTPUT CIRCUIT
Seven high current output terminals are provided on the Model CB-845X output unit to
supply a continuously adjustable output current for a wide variety of test circuit current
requirements.
The output circuit is not grounded and is not polarity sensitive so the current output
terminals can be used interchangeably without regard to polarity.
The maximum current available will depend on the current requirements and
impedance of the device to be tested as well as the current leads selected to perform the
test, the power input cable and the capacity of the power source available at the test site.
IT SHOULD BE NOTED THAT THERE IS NO RELATIONSHIP BETWEEN THE

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AMMETER RANGES AND THE RATING OF THE OUTPUT TERMINAL. All
ammeter ranges can be used in conjunction with the output terminals for any output
current level that does not exceed the ammeter range selected.
SELECTION OF OUTPUT LEADS
OUTPUT CONNECTIONS:
Model CB-845X is equipped with output connection bars for attachment of the high
current test leads provided or any others suitable for the test application.
The following information on the selection of output leads will provide the user with a
guide for choosing the proper test leads for his application.
Due to the voltage drop from the inductive reactance of the test circuit, a significant loss
of current will result for each inch of test lead. Therefore, when choosing test leads, the
length and size of leads chosen will determine the maximum available test current. 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 increase in available test
current. Heating is not a significant problem in testing, even though the leads become
hot. Paralleling of sufficient cables provides higher test currents. Each cable can be
fitted with a compression lug on each end, then bolted to the output terminals or stab
board of the test set.
When testing ground grids, the two cables between the test set and the ground grid
should be twisted together or bundled with tape or cord to maintain the close proximity
which minimizes inductive reactance.
OVERLOAD CAPACITY
Model CB-845X is rated at 5.5 kVA output and has two output terminals capable of
supplying rated current. The current rating of these output terminals may be exceeded
for short durations provided the voltage is sufficient to "push" the desired current
through the device under test and the connecting test leads. The figures below
represent the overload capacity at a given output current at 77 degrees (25 C) versus
time ON and time OFF
PERCENT
RATED CURRENT
MAXIMUM
TIME ON
MINIMUM
TIME OFF
100 % 30 minutes
30 minutes
200 % 75 seconds 6 minutes
300 % 25 seconds 4 minutes

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TEST PROCEDURES FOR
MOTOR OVERLOAD RELAYS
TIME DELAY
1. Set-up CB-845X with:
a. Power ON/OFF Switch in OFF position (instrument displays off).
b. OUTPUT CONTROL Knob at minimum "0" position.
c. OUTPUT MODE Switch in center OFF position.
d. Proper INPUT VOLTAGE selected.
2. Connect one end of a high-current lead to one side of thermal element or current
coil in overload relay. Connect other end of this lead to the appropriate output
terminal of test set.
3. Connect one end of second high-current lead to other side of thermal element or
current coil in overload relay. Connect other end of this lead to the common
terminal (see SELECTION OF OUTPUT LEADS, page Error! Bookmark not
defined.).
4. Connect test set to suitable single-phase power supply.
5. Turn test set ON with POWER ON/OFF Switch (instrument displays should
light).
6. Use RANGE SWITCH to select ammeter range so test current will be near full
scale and no less than 10% of full scale.
7. Put ammeter DISPLAY MODE Switch in MEMORY position.
8. Connect a pair of light leads (timer leads) from Normally Closed Contacts or
Normally Open Contacts of overload relay to binding posts of test set labeled
CONTACTS.
9. Select appropriate timer STOP MODE.
10. Select desired timer display mode and range.
11. Rotate OUTPUT CONTROL knob clockwise and momentarily press OUTPUT
MODE Switch in MOM. and release. Observe current reading retained by
ammeter.
12. Continue to rotate OUTPUT CONTROL Knob clockwise while jogging
(repeatedly moving to MOM. position and releasing) OUTPUT MODE Switch
until desired test current is reached. Suggested test current is three times (3x) the

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rating of thermal relays or three times (3x) the pick-up current of magnetic
relays.
NOTE: If the relay utilizes a high impedance thermal element or operating coil
and the desired current cannot be reached with OUTPUT CONTROL
Knob at maximum clockwise rotation, return knob to zero and change
leads to shorter and/or larger cross sectional size. Repeat steps 11 an 12
(see SELECTION OF OUTPUT LEADS, page Error! Bookmark not
defined.).
NOTE: Before starting test, allow time for thermal element to cool; or in the case
of magnetic overload relays, for the piston to reset. Incorrect tripping time
may otherwise result.
13. Put ammeter DISPLAY MODE in NORMAL position.
14. Start test by moving OUTPUT MODE Switch to MAINT. position.
NOTE: Test current may decrease (fall off) during the test because the resistance
or impedance of the test circuit increases as it heats up. Rotate OUTPUT
CONTROL Knob clockwise to keep test current at desired value.
15. When overload relay trips, timer stops and output is de-energized. Timer
indicates total elapsed time of the test in seconds or cycles.
16. Turn test set OFF with POWER ON/OFF Switch.
IMPORTANT NOTE
In order to obtain accurate tripping times with some types of magnetic overload relays,
particularly those using viscosity oil, it may be necessary to "preheat" the relay by
running rated current through the relay for a few minutes.
INSTANTANEOUS ELEMENT
1. Set-up CB-845X with:
a. Power ON/OFF Switch in OFF position (instrument displays off).
b. OUTPUT CONTROL Knob at minimum "0" position.
c. OUTPUT MODE Switch in center OFF position.
d. Proper INPUT VOLTAGE selected.
2. Connect one end of a high-current lead to one side of instantaneous element in
overload relay. Connect other end of this lead to the appropriate output terminal
of test set.
3. Connect one end of second high-current lead to other side of instantaneous

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element in overload relay. Connect other end of this lead to the common
terminal (see SELECTION OF OUTPUT LEADS, page Error! Bookmark not
defined.).
4. Connect test set to suitable single-phase power supply.
5. Turn test set ON with POWER ON/OFF Switch (instrument displays should
light).
6. Use RANGE Switch to select ammeter range so test current will be near full scale
and no less than 10% of full scale.
7. Put ammeter DISPLAY MODE Switch in MEMORY position.
8. Connect a pair of light leads (timer leads) from Normally Closed Contacts or
Normally Open Contacts of overload relay to binding posts of test set labeled
CONTACTS.
9. Select appropriate timer STOP MODE.
10. Select desired timer display mode and range.
11. Rotate OUTPUT CONTROL Knob clockwise and momentarily press OUTPUT
MODE Switch in MOM. and release. Observe current reading retained by
ammeter.
NOTE: If the relay utilizes a high impedance thermal element or operating coil
and the desired current cannot be reached with OUTPUT CONTROL
Knob at maximum clockwise rotation, return knob to zero and change
current leads to shorter and/or larger cross sectional size. Repeat step 11.
12. Continue step 11 until overload relay trips. Observe current reading retained on
ammeter. Timer indicated elapsed time of test in cycles or seconds.
NOTE: To avoid tripping error caused by interference of time delay element,
allow thermal element to cool; or in the case of magnetic overload relays,
for the position to reset.
13. Repeat test, starting with OUTPUT CONTROL Knob at position just below trip
current of instantaneous element observed in step 12.
14. When overload relay trips, timer stops and output is de-energized. Current
reading is retained on ammeter. Timer indicates elapsed time in seconds or
cycles.
15. Turn test set OFF with POWER ON/OFF Switch.

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IMPORTANT NOTE
Refer to the manufacturer's instructions for instantaneous trip time. If increasing test
current does not decrease tripping time, current at which minimum tripping time was
first observed is the instantaneous trip current value.

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TEST PROCEDURES FOR
MOLDED CASE CIRCUIT BREAKERS
THERMAL ELEMENT
1. Set-up CB-845X with:
a. Power ON/OFF Switch in OFF position (instrument displays off).
b. OUTPUT CONTROL Knob at minimum "0" position.
c. OUTPUT MODE Switch in center OFF position.
d. Proper INPUT VOLTAGE selected.
2. Connect one end of a high-current lead to one pole of side of circuit breaker.
Connect other end of this lead to a high current output terminal of test set.
3. Connect one end of second high-current lead to other side of same pole of circuit
breaker. Connect other end of this lead to the common terminal (see
SELECTION OF OUTPUT LEADS, page Error! Bookmark not defined.).
4. Connect test set to suitable single-phase power supply.
5. Turn test set ON with POWER ON/OFF Switch (instrument displays should
light).
6. Use RANGE Switch to select ammeter range so test current will be near full scale
and no less than 10% of full scale.
7. Put ammeter DISPLAY MODE Switch in MEMORY position.
8. Place timer STOP MODE Switch in CURRENT position.
9. Select desired timer display mode and range.
10. Rotate OUTPUT CONTROL Knob clockwise and momentarily press OUTPUT
MODE Switch in MOM. and release. Observe current reading retained by
ammeter.
11. Continue to rotate OUTPUT CONTROL Knob clockwise while jogging
(repeatedly moving to MOM. position and releasing) OUTPUT MODE Switch
until desired test current is reached. Suggested test current is three times (3x) the
rating of the circuit breaker.
NOTE: If the relay utilizes a high impedance thermal element or operating coil
and the desired current cannot be reached with OUTPUT CONTROL
Knob at maximum clockwise rotation, return knob to zero and change
current leads to shorter and/or larger cross sectional size. Repeat steps 10