20
Instruction Book
IB182023EN March 2016 www.eaton.com
AMH-4.76-VR
Replacement Circuit Breaker
WARNING
KEEP HANDS OFF THE TOP EDGE OF THE FRONT BARRIER WHEN PUSHING
A BREAKER INTO A CELL. FAILURE TO DO SO COULD RESULT IN BODILY
INJURY, IF FINGERS BECOME WEDGED BETWEEN THE BREAKER AND
THE CELL. USE THE HANDLES PROVIDED ON THE FRONT OF THE BREAKER
FACEPLATE, OR USE BOTH FULLY OPENED HANDS FLAT ON THE FRONT OF
THE FACEPLATE.
These checks can be performed with the breaker in its withdrawn
or disconnect position and connecting the breaker to a test cabinet
or to the switchgear cell’s secondary receptacle using the special
extension cable designed for this purpose and described in Section
3.
Perform electrical operations checks. Close and trip the circuit
breaker electrically several times to verify that the operation is
reliable and consistent. Check that the operation of the spring
charging motor is reasonably prompt and that the motor makes no
unusual noise.
WARNING
DO NOT PERFORM ELECTRICAL OPERATION CHECKS WITH THE BREAKER
IN THE “CONNECT” POSITION BECAUSE OF THE POSSIBILITY OF
CONNECTING DE-ENERGIZED LOAD CIRCUITS TO THE ELECTRICAL POWER
SOURCE, RESULTING IN DEATH, PERSONNEL INJURY OR EQUIPMENT
Sttp 11e:
After an adjustment is made, make sure that all nuts are
secured in place, prior to returning to service.
5.3 MANUAL OPERATION CHECK
Manual operational checks must be performed before the breaker
is connected to an energized circuit. Tests must be performed with
the breaker withdrawn from the cell or in the disconnect position.
While the breaker is withdrawn or in the disconnect position, place
the maintenance tool into the manual charge socket opening and
charge the closing springs with about 36 up and down strokes of
the handle. When charging is complete, the closing crank goes over
center with an audible “click” and the springs Charged / Discharged
Indicator shows “Charged”. Remove the maintenance tool.
NOTICE
IF THE SPRINGS ARE TO BE CHARGED ON A CLOSED BREAKER, NO
CLICK IS HEARD AT THE END OF CHARGING OPERATION. DISCONTINUE
CHARGING AND REMOVE THE MAINTENANCE TOOL AS SOON AS
“CHARGED” FLAG IS FULLY VISIBLE. CONTINUE ATTEMPTS TO FURTHER
CHARGE MAY RESULT IN DAMAGE TO THE MECHANISM.
WARNING
ALWAYS REMOVE THE MAINTENANCE TOOL AFTER CHARGING THE
SPRING. FAILURE TO REMOVE THE MAINTENANCE TOOL FROM THE
BREAKER COULD CAUSE INJURY TO PERSONNEL AND/OR EQUIPMENT
DAMAGE IF THE BREAKER WAS TO CLOSE.
Close and trip the breaker by pushing the close lever then the trip
lever (Figure 3.3).
5.4 VACUUM INTERRUPTER INTEGRITY
Using a dry lint-free cloth or a paper towel, clean all the insulating
surfaces of the pole units. Conduct a vacuum interrupter integrity
check as described in Section 6.
5.5 LOW FREQUENCY WITHSTAND TEST (INSULATION
CHECK)
Check breaker primary and secondary insulation per Section 6.
5.6 CONTACT EROSION AND WIPE
Manually charge the closing springs and close the breaker. Check
contact erosion and wipe as described in Section 6.
5.7 PRIMARY CIRCUIT RESISTANCE
Check the primary circuit resistance as described in Section 6. The
resistance should not exceed the values specified. Record the values
obtained for future reference.
5.8 ELECTRICAL OPERATIONS CHECK
After going through the above steps, the breaker is now ready to be
operated electrically. It is preferred that this check be made with the
breaker in the Test position in the breaker compartment.
Since the Type AMH-4.76-VR Circuit Breaker is for use in existing
AMH Metal-Clad Switchgear, installation procedures are similar. If it
is necessary to reference anything in the breaker compartment, refer
to the original instruction books supplied with the assembly.
WARNING
EXAMINE THE INSIDE OF THE CELL BEFORE INSERTING THE BREAKER
FOR EXCESSIVE DIRT OR ANYTHING THAT MIGHT INTERFERE WITH THE
BREAKER TRAVEL.
Figurt 5.2. AMH-VR in tht Disconntct Position
