WEG Molded Case Circuit Breakers - User’s Manual
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WEG Molded Case Circuit Breakers - User’s Manual
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3.2. CIRCUIT BREAKER RESET
After a trip operation, the circuit breaker is reset by moving the circuit breaker
handle to the Reset (extreme OFF) position.
Notes: In the event of a thermal (overload) trip the circuit breaker cannot be reset immediately. In a breaker with a
thermal-magnetic type trip unit the thermal element needs to cool (up to approximately five minutes) before it
can be reset. No circuit breaker should be reclosed until the cause of trip is known and the situation rectified.
3.3. PUSH-TO-TRIP BUTTON
The PUSH-TO-TRIP button operates the circuit breaker tripping function and may
be used to periodically exercise the operating mechanism. In thermal-magnetic
trip units, the button is designed to be operated by a small screw driver.
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 screw driver. The buttons
have several settings as indicated on the nameplate with values in multiples of the
trip unit ampere rating (I
n
) as shown in Figure 7. To adjust the setting, rotate each
button clockwise until arrow on button points to desired setting.
Magnetic adjustment
buttons
Push-to-trip
7.5
7.5
7.5
5
5
5
10
10
10
Amps (ln.)
Cat. No.
ºC
Magnetic -
multiples of ln
Thermal-
magnetic
trip unit
Push-to-trip
button
Figure 7:
trip unit magnetic adjustment buttons
4. INSPECTION AND FIELD TESTING
UBW600 molded case circuit breakers are designed to provide years of almost
maintenance-free operation. The following procedure describes how to do a
limited amount of field inspection and testing of a circuit breaker.
4.1. INSPECTION
Circuit breakers in service should be inspected periodically. The inspection should
include the following checks 1 through 8.
