scheider electric MiCOM P746, Technical Manual

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Commissioning and Maintenance P746/EN CM/F21
MiCOM P746 (CM) 10-17
CM
6. SETTING CHECKS
The setting checks ensure that all of the application-specific relay settings (i.e. both the
relay’s function and programmable scheme logic settings), for the particular installation, have
been correctly applied to the relay.
Note 1: The trip circuits should remain isolated during these checks to prevent
accidental operation of the associated circuit breaker.
Note 2: For busbar protection stability reasons, whatever is the maintenance
mode selected, the Check Zone will never be disabled, thus, the time
to inject current shall be shorter than the ID>1 set timer to avoid
Circuitry Fault alarms.
6.1 Apply application-specific settings
There are two methods of applying the settings to the relay:
−
Transferring them from a pre-prepared setting file to the relay using a portable PC
running the appropriate software via the relay’s front EIA(RS)232 port, located under
the bottom access cover. This method is preferred for transferring function settings as
it is much faster and there is less margin for error. If the programmable scheme logic
other than the default settings with which the relay is supplied is to be used then this is
the only way of changing the settings.
If a setting file has been created for the particular application and provided on a digital
medium, this will further reduce the commissioning time and should always be the
case where application-specific programmable scheme logic is to be applied to the
relay.
−
Enter them manually via the relay’s operator interface. This method is not suitable for
changing the programmable scheme logic.
Note: It is essential that where the installation needs application-specific
Programmable Scheme Logic, that the appropriate .psl file is downloaded
(sent) to the relay, for each and every setting group that will be used. If the
user fails to download the required .psl file to any setting group that may be
brought into service, then factory default PSL will still be resident. This may
have severe operational and safety consequences.
6.2 Demonstrate Correct Relay Operation
The purpose of these tests is as follows:
−
To determine that the primary protection function of the relay, current differential, can
trip according to the correct application settings.
−
To verify correct setting of any phase overcurrent protection.
−
To verify correct assignment of the inputs, relays and trip contacts, by monitoring the
response to a selection of fault injections.
6.2.1 Current Differential Bias Characteristic
To avoid spurious operation of any Overcurrent, earth fault or breaker fail elements, these
should be disabled for the duration of the differential element tests. This is done in the relay’s
CONFIGURATION column. Ensure that cells, [Overcurrent Prot], [Earth Fault Prot] and [CB
Fail & I<] are all set to “Disabled”. Make a note of which elements need to be re-enabled
after testing.