53
Section 7: Inspection and maintenance
Series NRX with PXR - type RF low voltage power (air) circuit breakers instruction manual
MN013002ENH03 September 2016 www.eaton.com
Section 7: Inspection and maintenance
General
WARNING
Failure to inspect, clean, and maintain circuit breakers
can reduce equipment life or cause the equipment to
not operate properly under fault conditions. This could
result in equipment damage, bodily injury, or even
death.
WARNING
The circuit breaker mechanism contains stored mechani-
cal energy and moving parts and should be operated
with the front cover and arc chutes in place. Parts may
move forcefully and without warning. If the front cover
or arc chutes have been removed, limit contact to the
handle and buttons. Failure to do so may result in seri-
ous bodily injury.
CAUTION
Inspection and maintenance procedures should be carried
out only by personnel familiar with the hazards associated
with working on power circuit breakers. Additionally, they
should become familiar with the specifics associated with
series NRX circuit breakers as presented in this manual.
Because of the variability of application conditions and the
great dependence placed upon these circuit breakers for
protection and the assurance of service continuity, inspec-
tion and maintenance activities should take place on a regu-
larly scheduled basis. Since maintenance of these circuit
breakers consists mainly of keeping them clean, the fre-
quency of scheduled inspection and maintenance depends
to some degree on the cleanliness and humidity of the
surroundings. It is recommended that maintenance record
sheets be completed for the equipment.
General recommendations
Circuit breaker cleaning activities should be a part of an
overall activity that includes the assembly in which the
circuit breaker is installed. Loose dust and dirt can be
removed from external surfaces using an industrial quality
vacuum cleaner and/or lint-free cloth. Unless otherwise
indicated, never use high pressure blowing air, since dirt or
foreign objects can be driven into areas, such as the breaker
mechanism, where additional friction sources could create
problems. Never use a wire brush to clean any part of the
circuit breaker.
When to inspect
Industry standards for this type of equipment recommend
a general inspection and lubrication after the number of
operations listed in Table 6. This should also be conducted
at the end of the first six months of service, if the number
of operations has not been reached.
Table 6. Inspection frequency.
Breaker frame size
Interval (cycles)
1
800 A and below
1750
Between 800 and 4000 A
500
1
Cycle = 1 open/close operation.
After the first inspection, inspect at least once a year. If
these recommended inspections show no maintenance
requirements, the period may be extended to a more eco-
nomical point. Conversely, if the recommended inspection
shows, for instance, a heavy accumulation of dirt or other
foreign matter or other electrical damage, the inspection
and maintenance interval should be decreased.
What to inspect
IMPORTANT
Before doing any work, make sure a drawout breaker is
levered out to the TEST, DISCONNECT, or WITHDRAWN
position. During the levering out and levering in of the cir-
cuit breaker, be aware of any signs that would indicate that
the levering process is not working properly. If working on
a fixed circuit breaker, bus systems should be de-energized
for convenience and safety. All circuit breakers should be
switched to the OFF position and the mechanism springs
discharged.
Once the circuit breaker has been cleaned as described pre-
viously under the topic entitled “General recommendations,”
visually inspect it for any signs of damage, missing or loose
parts, and unusual wear. Be especially alert for foreign mat-
ter that must be removed. On drawout circuit breakers,
inspect the primary disconnect finger clusters for signs of
wear and erosion (Figure 2). Make appropriate corrections
to anything found out of order.
Functional field testing
Eaton recommends that the following three functional
tests be performed on series NRX circuit breakers as part
of any maintenance procedure. Circuit breakers should be
removed from service and Eaton notified if the circuit break-
er fails to perform any of these tests successfully. Provide
the number of operations the breaker has performed to date
as well as the following nameplate information (Figure 61).
1.
G.O. #:
It:
Seq:
2.
Cust. P.O.:
3.
Date code
4.
Cat#:
!
