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6.7.3
Replacing Failed Relay Unit
If the failure is identified to be in the relay unit and the user has a spare relay unit, the user can
recover the protection by replacing the failed relay unit.
Repair at the site should be limited to relay unit replacement. Maintenance at the component level
is not recommended.
Check that the replacement relay unit has an identical Model Number and relay version (software
type form) as the removed relay.
The Model Number is indicated on the front of the relay. For the relay version, see Section 4.2.5.5.
Replacing the relay unit
CAUTION
After replacing the relay unit, check the settings.
The procedure of relay withdrawal and insertion is as follows:
• Switch off the DC power supply.
WARNING
• Disconnect the trip outputs, BI, BO, communication circuits, etc.
• Short-circuit all AC current inputs. Open all AC voltage inputs.
• Unscrew the relay front cover.
• Unscrew the binding screw on the panel.
• To remove the relay unit.
• Install the (spare) relay unit in the reverse procedure.
6.7.4
Resumption of Service
After replacing the failed relay unit or repairing failed external circuits, take the following
procedures to restore the relay to the service.
• Switch on the DC power supply and confirm that the "RUN" green LED is lit and the
"ALARM" red LED is not lit.
• Supply the AC inputs and reconnect the trip outputs, other circuits.
6.7.5
Storage
The spare relay should be stored in a dry and clean room. Based on IEC Standard 60255-6 the
storage temperature should be − 25 ° C to +70 ° C, but the temperature of 0 ° C to +40 ° C is
recommended for long-term storage.
Hazardous voltage may remain in the DC circuit just after switching off the
DC power supply. It takes about 30 seconds for the voltage to discharge.
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