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WEG Molded Case Circuit Breakers - User’s Manual
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3.3. PUSH-TO-TRIP BUTTON
The PUSH-TO-TRIP button checks the circuit breaker tripping function and is
used to periodically exercise the operating mechanism in thermal-magnetic trip
units. The button is designed to be operated by a small screwdriver.
3.4. THERMAL-MAGNETIC TRIP UNIT ADJUSTMENT
The magnetic element of each pole of the trip unit can be adjusted by rotating the
adjustment buttons on the front face of the trip unit with a screwdriver. The buttons
have several settings as indicated on the nameplate with values in multiples of the
trip unit ampere rating (Ih) as shown in Figure 9. To adjust the setting, rotate
each button clockwise until arrow button points to desired setting.
Adjustment buttons
Figure 9:
trip unit magnetic adjustment buttons
4. INSPECTION AND FIELD TESTING
UBW400 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.
4.1. INSPECTION AND FIELD TESTING
Circuit breakers in service should be inspected periodically. The inspection should
include the following checks 1 through 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
Some commercial cleaning agents will damage the nameplates or molded
parts. Make sure that cleaning agents or solvents used to clean the circuit
breaker are suitable for the job.
