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WEG Molded Case Circuit Breakers - User’s Manual
10
Adjustment
buttons
Figure 8:
trip unit magnetic trip adjustment buttons
3.5. INSPECTION AND FIELD TESTING
UBW250 molded case circuit breakers are designed to provide years of almost
maintenance-free operation.
The following procedure describes how to inspect and test a circuit breaker in
service.
3.6. INSPECTION
Circuit breakers in service should be inspected periodically. The inspection should
include the following checks (4-1 through 4-8):
WARNING
The voltages in energized equipment can cause death or severe personal
injury. Before inspecting the circuit breaker in an electrical system, make
sure there is no voltage present where work is to be performed. Special
attention should be paid to reverse feed applications to ensure no voltage
is present.
CAUTION
Make sure that cleaning agents or solvents used to clean the circuit breaker
are suitable for the job. Some commercial cleaning agents will damage the
nameplates or molded parts.
1. Remove dust, dirt, soot, grease, or moisture from the surface of the circuit
breaker using a lint-free dry cloth, brush, or vacuum cleaner. Do not blow
debris into circuit breaker. If contamination is found, look for the source and
eliminate the problem.
2. Switch circuit breaker to ON and OFF several times to be sure that the
mechanical linkages are free and do not bind. If mechanical linkages are not
free, replace circuit breaker.
3. With the circuit breaker in the ON position, press the PUSH TO-TRIP button
to mechanically trip the circuit breaker. Trip, reset, and switch circuit breaker
ON several times. If mechanism does not reset each time the circuit breaker is
tripped, replace the circuit breaker.
