Current Differential - GE L30 Instruction Manual

CHAPTER 9: COMMISSIONING
3. Disconnect the fiber Channel 1(2) Tx cable for less than 66 ms (not possible with direct fiber module).
Expected result
ACTUAL VALUES  STATUS  CHANNEL TESTS  CHANNEL 1(2) STATUS
ACTUAL VALUES  STATUS  CHANNEL TESTS  REMOTE LOOPBACK STATUS
ACTUAL VALUES  STATUS  CHANNEL TESTS  PFLL STATUS
If fault conditions are applied to the relay during these tests, it trips with a specified 87L operation time.
4. Disconnect the fiber Channel 1(2) Tx cable for more than 66 ms but less than 5 seconds.
Expected result
ACTUAL VALUES  STATUS  CHANNEL TESTS  CHANNEL 1(2) STATUS
ACTUAL VALUES  STATUS  CHANNEL TESTS  REMOTE LOOPBACK STATUS
ACTUAL VALUES  STATUS  CHANNEL TESTS  PFLL STATUS
If fault conditions are applied to the relay (after the channel is brought back) during these tests, it trips with a specified
87L operation time plus 50 to 80 ms required for establishing PFLL after such interruption.
5. Disconnect the fiber Channel 1(2) Tx cable for more than five seconds.
Expected result
ACTUAL VALUES  STATUS  CHANNEL TESTS  CHANNEL 1(2) STATUS
ACTUAL VALUES  STATUS  CHANNEL TESTS  REMOTE LOOPBACK STATUS
ACTUAL VALUES  STATUS  CHANNEL TESTS  PFLL STATUS
6. Reconnect the fiber Channel 1(2) Tx cable and in six to eight seconds confirm that the relays have re-established
communications again with the following status checks:
ACTUAL VALUES  STATUS  CHANNEL TESTS  CHANNEL 1(2) STATUS
ACTUAL VALUES  STATUS  CHANNEL TESTS  REMOTE LOOPBACK STATUS
ACTUAL VALUES  STATUS  CHANNEL TESTS  PFLL STATUS
7. Apply a current of 0.5 pu at a frequency 1 to 3% higher or lower than nominal only to local relay phase A to verify that
frequency tracking does not affect PFLL when only one relay has a current input and both relays track frequency. Wait
200 seconds and verify the following:
ACTUAL VALUES  STATUS  CHANNEL TESTS  PFLL STATUS
ACTUAL VALUES  METERING  TRACKING FREQUENCY  TRACKING FREQUENCY
For three-terminal configuration, carry out the test accordingly.

9.1.3 Current differential

The 87L element has adaptive restraint and dual slope characteristics. The pickup slope settings and the breakpoint
settings determine the element characteristics. The relay displays both local and remote current magnitudes and angles
and the differential current that helps with start-up activities. When a differential condition is detected, the output
operands from the element are asserted along with energization of faceplate event indicators.
1. Ensure that relay will not issue any undesired signals to other equipment.
2. Ensure that relays are connected to the proper communication media, communications tests have been performed
and the CHANNEL and PFLL STATUS displays indicate OK.
3. Minimum pickup test with local current only:
3.1. Ensure that all 87L setting are properly entered into the relay and connect a test set to the relay to inject
current into Phase A.
L30 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
: "OK"
: "n/a"
: "OK"
: "OK"
: "n/a"
: "OK"
: "OK"
: "n/a"
: "Fail"
: "OK"
: "n/a"
: "OK"
: "OK"
: actual frequency at both relays
TESTING
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