Alstom MiCOM P846, Technical Manual

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Commissioning P846/EN CM/D
MiCOM P846
(CM) 10-9
5. PRODUCT CHECKS
These product checks cover all aspects of the relay which should be checked to ensure that
it has not been physically damaged prior to commissioning, is functioning correctly and all
input quantity measurements are within the stated tolerances.
If the application-specific settings have been applied to the relay prior to commissioning, it is
advisable to make a copy of the settings so as to allow their restoration later. This could be
done by:
•
Obtaining a setting file on a diskette from the customer (this requires a portable PC with
appropriate setting software for transferring the settings from the PC to the relay)
•
Extracting the settings from the relay itself (this again requires a portable PC with
appropriate setting software)
•
Manually creating a setting record. This could be done using a copy of the setting
record located at the end of this chapter to record the settings as the relay’s menu is
sequentially stepped through via the front panel user interface
If password protection is enabled and the customer has changed password 2 that prevents
unauthorized changes to some of the settings, either the revised password 2 should be
provided, or the customer should restore the original password prior to commencement of
testing.
Note: In the event that the password has been lost, a recovery password
can be obtained from Alstom Grid by quoting the serial number of the
relay. The recovery password is unique to that relay and is unlikely to
work on any other relay.
5.1 With the relay de-energized
The following group of tests should be carried out without the auxiliary supply being applied
to the relay and with the trip circuit isolated.
The current and voltage transformer connections must be isolated from the relay for these
checks. If a P991 test block is provided, the required isolation can easily be achieved by
inserting test plug type P992 that effectively open-circuits all wiring routed through the test
block.
CM
Before inserting the test plug, reference should be made to the scheme (wiring) diagram to
ensure that this will not potentially cause damage or a safety hazard. For example, the test
block may be associated with protection current transformer circuits. It is essential that the
sockets in the test plug, which correspond to the current transformer secondary windings,
are linked before the test plug is inserted into the test block.
DANGER: Never open circuit the secondary circuit of a current transformer since
the high voltage produced may be lethal and could damage insulation.
If a test block is not provided, the voltage transformer supply to the relay should be isolated
by means of the panel links or connecting blocks. The line current transformers should be
short-circuited and disconnected from the relay terminals. Where means of isolating the
auxiliary supply and trip circuit (e.g. isolation links, fuses, MCB, etc.) are provided, these
should be used. If this is not possible, the wiring to these circuits will have to be
disconnected and the exposed ends suitably terminated to prevent them from being a safety
hazard.
5.1.1 Visual inspection
The rating information given under the top access cover on the front of the relay
should be checked. Check that the relay being tested is correct for the protected
line/circuit. Ensure that the circuit reference and system details are entered onto the
setting record sheet. Double-check the CT secondary current rating, and be sure to
record the actual CT tap which is in use.