Method Of Repair; Replacing The Active Part; Replacing The Complete Relay; Changing The Battery (Micom P126 & P127 Only) - Areva MiCOM P125 Technical Manual

Commissioning and Maintenance
MiCOM P125/P126 & P127
5.2

Method of repair

5.2.1

Replacing the active part

The case and the rear terminals blocks have been designed to facilitate removal of the
MiCOM P12x relay should replacement or repair become necessary without disconnect the
scheme wiring.
NOTE :
Remove the upper and lower flap without exerting excessive force. Remove the external
screws. Under the upper flap, turn the extractor with a 3 mm screwdriver and extract the
active part of the relay by pulling from the upper and lower notches on the front panel of the
MiCOM relay.
The reinstall the repaired or replacement relay follow the above instruction in reverse,
ensuring that no modification has been done on the scheme wiring.
5.2.2

Replacing the complete relay

To remove the complete relay (active part and case) the entire wiring must be removed from
the rear connector.
Before working at the rear of the relay, isolate all current supplies to the MiCOM relay and
ensure that the relay is no more powered.
DANGER:
Remove all wiring (communication, logic inputs, outputs, auxiliary voltage, current inputs).
Disconnect the relay earth connection from the rear of the relay.
Remove the screws used to fasten the relay to the panel, rack, etc... .These are the screws
with the larger diameter heads that are accessible when the upper and lower flaps are open.
Withdraw the relay from the panel, rack, etc... carefully because it will be heavy due to the
internal transformers.
To reinstall the repaired or replacement relay follow the above instructions in reverse,
ensuring that each terminal block is relocated in the correct position and case earth,
communication are replaced.
Once reinstallation is complete the relay should be recommissioned using the instruction in
sections 1 to 4 inclusive of this chapter.
5.2.3 Changing the battery (MiCOM P126 & P127 only)
Each MiCOM P126 and P127 relay has a battery to maintain recording data and the correct
time when the auxiliary voltage fails. The data maintained include event, fault and
disturbance records and the thermal state at the time failure.
The battery is designed for a life of 10 years in standard atmospheric conditions.
"RAM ERROR" message could be the result of a battery failure.
To replace the battery follow the following instructions :
•
Open the lower flap on the front of the relay
•
Gently extract the battery from its socket. If necessary, use a small screwdriver.
•
Ensure that metal terminals in the battery socket are free from corrosion, grease and
dust.
•
The replacement battery should be removed from its packaging and placed into the
battery holder, ensure that the polarity markings on the battery agree with those
adjacent to the socket.
NOTE :
The MiCOM relays have integral current transformer shorting switches
which will close when the active part is removed from the case.
NEVER OPEN CIRCUIT THE SECONDARY CIRCUIT OF A CURRENT
TRANSFORMER SINCE THE HIGH VOLTAGE PRODUCED MAY BE
LETHAL AND COULD DAMAGE INSULATION.
Only use a type 1/2AA lithium battery with a nominal voltage of 3.6 V.
P12y/EN CM/C22
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