26
FIG. 7.3.15.2, DEFLECTION GAUGE.
FIG. 7.3.15.1, CHECK MOVING CONTACT PINS.
FIG. 7.3.1 4.2 CHECKING CONTACT DIFFERENTIAL
1.
SLOW CLOSE HANDLE
2.
FEELER GAUGE
15. CHECK DEFLECTION.
BEFORE CHECKING THE CONTACT DEFLECTION, NOTE THAT
SHOULD ONE COME IN CONTACT WITH MANUAL TRIP BUTTON WHILE
THE BREAKER IS CLOSED, ACCIDENTAL TRIPPING COULD OCCUR. THIS
COULD BE INJURIOUS IF HANDLING THE MOVING CONTACTS. A GOOD
PRECAUTION AGAINST THIS IS TO INSERT A NUT AND BOLT IN THE
TRIP BUTTON.
WITH THE CONTACTS CLOSED, CHECK THE PIN THAT PASSES
THROUGH THE WAFER CONTACTS FOR FREEDOM. IF THE CONTACT
HAS ADEQUATE DEFLECTION, THE PIN SHOULD BE COMPLETELY FREE
TO MOVE. IN THE FRONT-REAR DIRECTION, THE PIN SHOULD MOVE
MORE THAN 1/32 INCH. IF THE PIN IS NOT FREE, OR IF THE CONTACT
AREA HAS SHOWN ANY SIGNS OF OVERHEATING, THE DEFLECTION
SHOULD BE CHECKED WITH A DEFLECTION GAUGE.
TO USE THE GAUGE, BEGIN WITH THE CONTACTS OPEN. PUSH
THE INDICATOR ON THE GAUGE TOWARD THE ZERO MARK AND
INSERT THE GAUGE INTO THE LEFT SIDE OF THE MOVING
CONTACT ASSEMBLY. THE TWO LOWER LOCATORS ON THE GAUGE
REST IN THE HOLE IN THE SIDE OF THE CONTACT FRAME
SIDEPLATE, THE UPPER ONE ON THE TOP OF THE SIDEPLATE. NOW
RELEASE THE INDICATOR AND OBSERVE THE READING. REPEAT
FOR EACH CONTACT ON THE BREAKER.
THEN, CLOSE THE BREAKER AND AGAIN TAKE READINGS ON
EACH CONTACT. SUBTRACT THE OPEN READING FROM THE CLOSED
READING TO GET THE DEFLECTION IN 1/64 INCH. THE CORRECT
READING FOR BREAKERS UP TO AND INCLUDING 2000A IS 3/64 TO 5/64,
FOR BREAKERS ABOVE 2000A, 2/64 TO 4/64". AS WITH THE
DIFFERENTIAL, READINGS ABOVE THESE RANGES ARE ACCEPTABLE
AS LONG AS THE TOGGLE PIN IS AGAINST THE STOPS WHEN THE
BREAKER IS CLOSED.
IF DEFLECTION IS BELOW THE RANGE SPECIFIED, IT MAY BE
INCREASED BY ADDING SHIMS TO THE CLOSING LINK. LOOSEN THE
TWO BOLTS, INSERT A SHIM AND RETIGHTEN THE BOLTS FIRMLY.
NOW, CHECK THAT THE TOGGLE PIN IS STILL AGAINST THE
STOPS IN THE CLOSED POSITION AND REDO THE DEFLECTION
READINGS IN THE CLOSED POSITION. REPEAT UNTIL ACCEPTABLE
DEFLECTION READINGS ARE OBTAINED ON ALL CONTACTS.
FIG. 7.3.1 5.3, DEFLECTION READING IN OPEN POSITION.
