Alstom MiCOM P846, Technical Manual

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Commissioning P846/EN CM/D
MiCOM P846
(CM) 10-23
7. ON-LOAD CHECKS
The objectives of the on-load checks are to:
−
Confirm the external wiring to the current and voltage inputs is correct.
−
Check the polarity of the line current transformers at each end is consistent.
However, these checks can only be carried out if there are no restrictions preventing the
energization of the plant being protected and the other P846 relays in the group have been
commissioned.
Remove all test leads, temporary shorting leads, etc. and replace any external wiring that
has been removed to allow testing.
If it has been necessary to disconnect any of the external wiring from the relay in order to
perform any of the foregoing tests, it should be ensured that all connections are replaced in
accordance with the relevant external connection or scheme diagram.
7.1 Confirm current and voltage transformer wiring
7.1.1 Voltage connections
Using a multimeter measure the voltage transformer secondary voltages to ensure they are
correctly rated. Check that the system phase rotation is correct using a phase rotation
meter.
Compare the values of the secondary phase voltages with the relay’s measured values,
which can be found in the MEASUREMENTS 1 menu column.
Voltage
Cell in MEASUREMENTS 1
column (02)
Corresponding VT Ratio in ‘VT
and CT RATIO‘ column (0A) of
menu)
VAB
VBC
VCA
VAN
VBN
VCN
[0214: VAB Magnitude]
[0216: VBC Magnitude]
[0218: VCA Magnitude]
[021A: VAN Magnitude]
[021C: VBN Magnitude]
[021E: VCN Magnitude]
Error! Bookmark not
defined.Error! Bookmark not
defined.
[0A01 : Main VT Primary]
[0A02 : Main VT Secondary]
CM
Table 10: Measured voltages and VT ratio settings
If cell [0D02: MEASURE’T. SETUP, Local Values] is set to ‘Secondary’, the values displayed
on the relay LCD or a portable PC connected to the front EIA(RS)232 communication port
should be equal to the applied secondary voltage. The values should be within 1% of the
applied secondary voltages. However, an additional allowance must be made for the
accuracy of the test equipment being used.
If cell [0D02: MEASURE’T. SETUP, Local Values] is set to ‘Primary’, the values displayed
should be equal to the applied secondary voltage multiplied the corresponding voltage
transformer ratio set in the ‘CT & VT RATIOS’ menu column (see Table 10). Again the
values should be within 1% of the expected value, plus an additional allowance for the
accuracy of the test equipment being used.