Rockwell Automation 140U Q and M-Frame Circuit Breakers Installation of Q-Frame Circuit Breakers - Manual (Page 6)

Page 6
ues in multiples of the trip unit ampere rating (I,) as
shown in Fig. 4-2. To adjust the setting, rotate each but-
ton clockwise until arrow on button points to desired set-
ting. The molded case switch is set at the factory (at
and is not field adjustable.
Interchangeable Trip Units
For additional information on thermal-magnetic trip units,
refer to I.L.
(3-pole) and I.L. (4-pole). For
electronic electronic RMS trip units, refer to I.L.
5. INSPECTION AND FIELD TESTING
Q-Frame 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.
Inspection
Circuit breakers in service should be inspected periodi-
cally. The inspection should include the following checks
5-1 through 5-8.
WARNING
THE VOLTAGES IN ENERGIZED EQUIPMENT CAN
CAUSE SEVERE PERSONAL INJURY OR DEATH.
BEFORE INSPECTING THE CIRCUIT BREAKER IN AN
ELECTRICAL SYSTEM, MAKE SURE THE CIRCUIT
BREAKER
IS SWITCHED TO THE
AND THAT 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.
VENTS USED TO CLEAN THE CIRCUIT BREAKER
ARE SUITABLE FOR THE JOB.
MAKE SURE THAT CLEANING AGENTS OR SOL-
5-1. 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.
5-2. Switch circuit breaker to ON and OFF several times
to be sure that the mechanical linkages operate
freely and do not bind. If mechanical linkages do
not operate freely, replace circuit breaker.
Note: On molded case switches, there is no
TO-TRIP feature. Omit step 5-3 when installing a
molded case switch and proceed with step
5-3.
5-4.
5-5.
5-6.
5-7.
5-8.
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.
Check base, cover, operating handle, and handle
barrier for cracks, chipping, and discoloration. Cir-
cuit breakers should be replaced
if cracks or severe
discoloration is found.
Check wire connecting terminals and other type
bus bar connectors for looseness or signs of over-
heating. Overheating will show as discoloration,
melting, or blistering of conductor insulation, or as
pitting or melting of conductor surfaces due to arc-
ing. If there is no evidence of overheating or loose-
ness, do not disturb or tighten the connections. If
there is evidence of overheating, terminations
should be cleaned or replaced. Before
ing the circuit breaker, all terminations and cable
should be refurbished to the originally installed con-
dition.
Check circuit breaker mounting hardware, and
tighten if necessary.
Exposure to certain types of chemicals can cause
deterioration of electrical connections. Check area
where circuit breaker is installed for any safety haz-
ards, including personal safety and fire hazards and
take required precautionary actions.
The operation of circuit breakers with electronic
RMS trip units can be field tested periodically using
the Electronic test kit. Contact Allen-Bradley
for details.
Field Testing
Any field testing should be done in accordance with appli-
cable NEMA Standard.
40752-078(1) Effective 5/02