20
Instruction Book
IB182923EN September 2018 www.eaton.com
AMH-4.76-VR
+
VR-Series
+
Replacement Circuit Breaker
SECTION 5: INSPECTION & INSTALLATION
m
WARNING
BEFORE PLACING THE CIRCUIT BREAKER IN SERVICE, CAREFULLY FOLLOW
THE INSTALLATION PROCEDURE BELOW AND THE SAFE PRACTICES SET
FORTH IN SECTION 2. NOT FOLLOWING THE PROCEDURE MAY RESULT IN
INCORRECT CIRCUIT BREAKER OPERATION LEADING TO DEATH, BODILY
INJURY, AND PROPERTY DAMAGE.
When the circuit breaker is first commissioned into service and each
time the circuit breaker is returned to service, it should be carefully
examined and checked to make sure it is operating correctly.
5.1 EXAMINATION FOR DAMAGE
Examine the cirucit breaker for loose or obviously damaged parts.
Never attempt to install nor operate a damaged circuit breaker.
5.1.1 NAMEPLATE VERIFICATION
Verify the information on the new VR- nameplate matches
the information on the purchase order. If any discrepancies exist,
notify Eaton’s Electrical Engineering Services & Systems for
resolution prior to proceeding.
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WARNING
ALWAYS DE-ENERGIZE/ISOLATE THE POWER SOURCE FEEDING THE
POWER CIRCUIT BREAKERS/SWITCHGEAR AND LOCK-OUT/TAG-OUT THE
POWER SOURCE PRIOR TO INSERTION OR REMOVAL OF ANY POWER
CIRCUIT BREAKER. NEVER ATTEMPT TO MAINTAIN OR MODIFY A CIRCUIT
BREAKER WHILE INSERTED IN A SWITCHGEAR CELL STRUCTURE. ALWAYS
REMOVE THE POWER CIRCUIT BREAKER AND MOVE IT TO A SUITABLE
AREA FOR MAINTENANCE OR REPAIR.
FOLLOW ALL LOCKOUT AND TAG-OUT REQUIREMENTS OF THE NATIONAL
ELECTRIC CODE, OSHA AND ANY OTHER APPLICABLE LOCAL CODES,
REGULATIONS AND PROCEDURES.
5.2 SURE CLOSE MECHANISM ADJUSTMENT
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WARNING
FOR ALL TYPE CIRCUIT BREAKER HOUSINGS EQUIPPED WITH MECHANISM
OPERATED CELL (MOC) SWITCHES, THE STEPS OUTLINED IN THIS SECTION
MUST BE PERFORMED BEFORE INSTALLING A REPLACEMENT VR-
CIRCUIT BREAKER. FAILURE TO COMPLY COULD CAUSE SEVERE PERSONAL
INJURY, DEATH, EQUIPMENT DAMAGE AND/OR IMPROPER OPERATION
All type AMH-4.76-VR+ breakers utilize the AMH-4.76-VR+
SURE
CLOSE
mechanism to control kinetic energy transfer and closely
mimic the dynamics and velocities of older circuit breakers. It is
imperative that this mechanism be adjusted to compensate for the
force of the MOC switch mounted in the cell.
The circuit breaker has been factory adjusted to operate one
mechanism operated cell (MOC) switch in the cell. This means that
for applications with either no MOC switch or one MOC switch, no
field adjustments are required.
Finally, the
SURE CLOSE
mechanism provides an effective way to
evaluate the condition of the MOC in the cell. If the
SURE CLOSE
drive spring is properly adjusted, but the MOC does not fully open
or close, it is time to maintain the MOC in the cell. Maintenance
usually means cleaning and lubricating the MOC mechanism.
If the MOC has seen a large number of cycles, however, worn
components may have to be replaced.
To insure the proper operation of the
SURE CLOSE
mechanism, the
MOC assembly should be cleaned and inspected for worn parts and
then lubricated. A spring force gauge should be used to measure the
forces needed to move the switch to the fully closed position prior
to inserting the circuit breaker. The differential force of the assembly
and the circuit breaker should be a minimum of 10 lbs. with the
circuit breaker having the higher recorded force. Should the forces
be less than that, proceed with the following steps to increase the
circuit breaker force:
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WARNING
MEASUREMENTS AND ADJUSTMENTS SHOULD NEVER BE ATTEMPTED
IN AN ENERGIZED STRUCTURE. IF THE STRUCTURE CAN NOT BE
DE-ENERGIZED, THEN PROPER PERSONAL PROTECTIVE EQUIPMENT
PER NFPA 70E MUST BE WORN AT ALL TIMES WHILE GATHERING MOC
SWITCH DATA, ADJUSTING OR SERVICING THE MOC SWITCH. FAILURE TO
COMPLY WITH THIS WARNING COULD CAUSE SEVERE PERSONAL INJURY,
DEATH, EQUIPMENT DAMAGE AND/OR IMPROPER OPERATION.
To adjust the
SURE CLOSE
drive spring for a specific number of
MOC switches, proceed with the following steps:
Sttp 1e:
Locate the MOC drive spring (Figure 3.3). It is located in the
left lower portion of the circuit breaker as viewed from the rear of
the circuit breaker.
Sttp 2e:
From the factory, the drive spring comes set with adequate
force to operate one MOC switch, however, more force can be
generated. Refer to Figure 5.1 to see how that adjustment would
look. Notice that there is a nut and a jam nut on the threaded rod
to make the adjustment easy.
Sttp 3e:
Using a spring gauge, measure the force required to
operate the MOC to the fully closed position in the cell at the
interface with the circuit breaker.
Sttp 4e:
With the breaker out of the cell, close the circuit breaker
and measure the output of the MOC drive with a spring gauge.
Open the circuit breaker. The MOC drive force should exceed the
MOC cell force required by 10 - 15lbs. If not, an adjustment is
required.
Sttp 5e:
Loosen the jam nut on the
SURE CLOSE
spring and
compress the spring an additional .25 inches. Close the circuit
breaker.
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WARNING
WITH THE CIRCUIT BREAKER IN THE OPEN POSITION, THE SPRING
COMPRESSION SHOULD NEVER BE SET TO A DIMENSION LESS THAN 3
INCHES AS MEASURED IN FIGURE 5.1.
Sttp 6e:
Remeasure the MOC output spring force in the closed
position. Repeat until the MOC forces are adequate.
Sttp 7e:
Insert into the cell.
Sttp 8e:
Operate the circuit breaker to verify the new setting.
Sttp 9e:
Repeat steps 3 - 7 until acceptable operation is achieved.
Sttp 10e:
Anytime an adjustment is made, make sure the new
Figurt 5.1.
SURE CLOSE
Spring Comprtssion Sttting