Technical Guide P92x/EN CM/E11
Commissioning Guide
MiCOM P921-P922-P923 Page 25/28
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8. PREVENTATIVE MAINTENANCE
8.1 Maintenance period
It is recommended that products supplied by AREVA receive periodic monitoring
after installation. As with all products some deterioration with time is inevitable. In
view of the critical nature of protective relays and their infrequent operation, it is
desirable to confirm that they are operating correctly at regular intervals.
AREVA protective relays are designed for a life in excess of 20 years.
The MiCOM P921-P922-P923 protection relays are self-checking. They thus require
less maintenance than models using earlier technologies. Most problems will result in
an alarm so that remedial action can be taken. However, some periodic tests should
be done to ensure that the relay is functioning correctly and the external wiring is
intact.
If a preventative maintenance policy exists within the customer’s organisation then the
recommended product checks should be included in the regular programme.
Maintenance periods will depend on many factors, such as:
· the operating environment
· accessibility of the site
· amount of available manpower
· importance of the installation in the power system
· consequences of failure
8.2 Maintenance checks
Although some functionality checks can be performed from a remote location by
utilising the communications ability of the relays, these are predominantly restricted to
checking that the relay is measuring the applied voltages accurately, and checking
the circuit breaker maintenance counters. Therefore it is recommended that
maintenance checks are performed locally (i.e. at the substation itself).
BEFORE CARRYING OUT ANY WORK ON THE EQUIPMENT, THE USER SHOULD BE
FAMILIAR WITH THE “SAFETY” SECTION IN THE “P92x/EN IN” CHAPTER OF THIS
MANUAL.
8.2.1 Alarms
The alarm status LED should first be checked to identify if any alarm conditions exist.
If so, press the read key 1 repeatedly to display the alarms individually. Clear the
alarms (key 0) to extinguish the LED.
8.2.2 Opto-isolated inputs
The opto-isolated inputs can be checked to ensure that the relay responds to their
energisation by repeating the commissioning test detailed in Section 4.2.4 of this
chapter.
8.2.3 Output relays
The output relays can be checked to ensure that they operate by repeating the
commissioning test detailed in Section 4.2.5 of this chapter.
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