Technical Guide P92x/EN CM/E11
Commissioning Guide
MiCOM P921-P922-P923 Page 27/28
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8.4 Changing the battery
Each relay has a battery to maintain records (P922-P923) and the correct time in case
the auxiliary supply fails. The data maintained in a P922-P923 relay thus includes
event, fault and disturbance records at the time of failure.
This battery will periodically need changing, although an alarm will be given as part
of the relay's periodic self-monitoring in the event of a low battery condition.
8.4.1 Instructions for replacing the battery
Open the bottom cover on the front of the relay.
Gently extract the battery from its socket. If necessary, use a small screwdriver to prize
the battery free.
Ensure that the 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, taking care to ensure that the polarity markings on the battery agree
with those adjacent to the socket.
NOTE: Only use a type ½AA lithium battery with a nominal voltage of
3.7V.
ENSURE THAT THE BATTERY IS SECURELY HELD IN ITS SOCKET AND THAT THE
BATTERY TERMINALS ARE MAKING GOOD CONTACT WITH THE METAL TERMINALS
OF THE SOCKET.
Close the bottom cover on the front of the relay.
8.4.2 Post modification tests
To ensure that the replacement battery will maintain the date and time if the auxiliary
supply fails, change the date and time on the relay, then disconnect and reconnect
the auxiliary supply. The date and time should be maintained.
8.4.3 Battery disposal
The battery that has been removed should be disposed of in accordance with the
disposal procedure for Lithium batteries in the country in which the relay is installed.
8.5 Cleaning
Before cleaning the equipment ensure that all inputs (auxiliary supply, current,
voltage) are isolated to prevent any risk of electric shock.
The equipment may be cleaned using a clean, damp cloth. Do not use detergents,
solvents or abrasive cleaners as they may damage the relay's surface and leave a
conductive residue.
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