Micom P721, Technical Manual

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Commissioning and Maintenance P72x/EN CM/C21
MiCOM P721/P723 Page 25/28
5.1.3 Hardware and software faults
Messages:
"DEFAULT SETTING": Indication that the relay is running the default setting
"SETTING ERROR": Failure in the setting
" CALIBRATION ERROR.": Calibration zone failure
"CT ERROR": Analogue channel failure
Cause:
Hardware or software failure
Action:
Restart the protection software (refer § 5.3).
If the software fault still remains after restart, withdraw the active part and return the module
to the factory for repair.
5.2 Method of repair
5.2.1 Replacing the active part
BEFORE CARRYING OUT ANY WORK ON THE EQUIPMENT, THE
USER SHOULD BE FAMILIAR WITH THE CONTENTS OF THE SAFETY
GUIDE SFTY/4LM/E11 OR LATER ISSUE, OR THE SAFETY AND
TECHNICAL DATA SECTIONS OF THE TECHNICAL MANUAL AND
ALSO THE RATINGS ON THE EQUIPMENT RATING LABEL.
The case and the rear terminals blocks have been designed to facilitate removal of the
MiCOM P72x relay should replacement or repair become necessary without disconnect the
scheme wiring.
NOTE: The MiCOM range of relays have integral current transformer shorting
switches which will close when the active part is removed from the
case.
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.
To reinstall the repaired or replacement relay follow the above instructions in reverse,
ensuring that no modification has been made to the scheme wiring.
On completion of any operations which require the relay to be removed from its case, verify
that the four fixing screws are fitted at the corners of the front panel under the flaps. These
screws secure the chassis (removable part) to the relay case, ensuring good seating and
contact.
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 longer powered.
WARNING: NEVER OPEN THE SECONDARY CIRCUIT OF A CURRENT
TRANSFORMER SINCE THE HIGH VOLTAGE PRODUCED MAY BE
LETHAL AND COULD DAMAGE THE INSULATION.
Remove all wiring (communication, logic inputs, outputs, auxiliary voltage, current inputs).
Disconnect the relay earth connection from the rear of the relay.