44
Series NRX Low Voltage Power (Air)
Circuit Breakers User Manual
EATON CORPORATION www.eaton.com
Instructional Book MN01301003E
Effective July 2011
Section 6: Inspection and Maintenance
General
WARNING
FAILURE TO INSPECT, CLEAN, AND MAINTAIN CIRCUIT BREAKERS CAN
REDUCE EQUIPMENT LIFE OR CAUSE THE EQUIPMENT NOT TO OPERATE
PROPERLY UNDER FAULT CONDITIONS. THIS COULD RESULT IN EQUIPMENT
DAMAGE, BODILY INJURY, OR EVEN DEATH.
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, inspection and maintenance activities
should take place on a regularly scheduled basis. Since maintenance
of these circuit breakers consists mainly of keeping them clean, the
frequency 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
800A and below 1750
Between 800 and 4000A 500
1
Cycle = 1 no load 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 economical 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 CIRCUIT 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 previously
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 matter that must be removed. On drawout
circuit breakers, inspect the primary disconnect finger clusters for
signs of wear and erosion (Figure 3). 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 breaker 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 48).
1. G.O. #: It: Seq:
2. Cust. P.O.:
3. Date Code
4. Cat#:
To Next Page
Loading...
Need help?
General
