Clock Synchronization Tests - GE L90 Instruction Manual

TESTING
Expected result — In a few seconds "Yes" changes to "Local Loopback Test PASSED" and then to "No", signifying the
test was successfully completed and the communication modules operated properly.
11. If Channel 2 is used, make the following setting change and repeat Step 10 for Channel 2 as performed for channel 1:
TESTING  CHANNEL TESTS  LOCAL LOOPBACK TEST  LOCAL LOOPBACK CHANNEL NUMBER
12. Verify and record that the Local Loopback Test was performed properly with the following status check:
ACTUAL VALUES  STATUS  CHANNEL TESTS  CHANNEL 1(2) LOCAL LOOPBACK STATUS
13. Make the following setting change in one of the relays:
TESTING  CHANNEL TESTS  REMOTE LOOPBACK TEST  REMOTE LOOPBACK CHANNEL NUMBER
14. Initiate the Remote Loopback Channel Tests by making the following setting change:
TESTING  CHANNEL TESTS  REMOTE LOOPBACK  REMOTE LOOPBACK FUNCTION
Expected result — The "Running Remote Loopback Test" message appears; within 60 to 100 seconds, the "Remote
Loopback Test PASSED" message appears for a few seconds and then changes to "No", signifying that the test
successfully completed and communications with the relay were successfully established. The "Remote Loopback
Test FAILED" message indicates that either the communication link quality does not meet requirements (BER less than
10–4) or the channel is not established – check the communications link connections.
15. If Channel 2 is used, make the following setting change and repeat Step 14 for Channel 2 as performed for Channel 1:
TESTING  CHANNEL TESTS  REMOTE LOOPBACK TEST  REMOTE LOOPBACK CHANNEL NUMBER
16. Verify and record the Remote Loopback Test was performed properly with the following status check:
ACTUAL VALUES  STATUS  CHANNEL TESTS  CHANNEL 1(2) REMOTE LOOPBACK STATUS
17. Verify and record that Remote Loopback Test fails during communications failures as follows: start test as per Steps
13 to 14 and in two to five seconds disconnect the fiber Rx cable on the corresponding channel.
Expected result — The "Running Remote Loopback Test" message appears. When the channel is momentarily cut off,
the "Remote Loopback Test FAILED" message displays. The status check reads as follows:
CHANNEL TESTS  CHANNEL 1(2) LOCAL LOOPBACK STATUS
18. Re-connect the fiber Rx cable. Repeat Steps 13 to 14 and verify that Remote Loopback Test performs properly again.
19. Verify and record that Remote Loopback Test fails if communications are not connected properly by disconnecting the
fiber Rx cable and repeating Steps 13 to 14.
Expected result — The
message is constantly on the display.
20. Repeat Steps 13 to 14 and verify that Remote Loopback Test is correct.
21. Make the following setting change in both relays:
During channel tests, verify in the
display that the values are very low or even 0. If values are comparatively high, check the settings of
communications equipment (if applicable).

9.1.2 Clock synchronization tests

The 87L clock synchronization is based upon a peer-to-peer architecture in which all relays are Masters. The relays are
synchronized in a distributed fashion. The clocks are phase-synchronized to each other and frequency-synchronized to the
power-system frequency. The performance requirement for the clock synchronization is a maximum error of ±130 μs.
All tests are verified by using PFLL status displays. All PFLL status displays must be either OK or Fail.
9
1. Ensure that Steps 1 through 7 inclusive of the previous section are completed.
2. Verify and record that both relays have established communications with the following checks after 60 to 120
seconds:
ACTUAL VALUES  STATUS  CHANNEL TESTS  CHANNEL 1(2) STATUS
ACTUAL VALUES  STATUS  CHANNEL TESTS  REMOTE LOOPBACK STATUS
ACTUAL VALUES  STATUS  CHANNEL TESTS  PFLL STATUS
9-2
ACTUAL VALUES  STATUS  CHANNEL TESTS  CHANNEL 1(2) REMOTE LOOPBACK TEST
TESTING  TEST MODE
ACTUAL VALUES  STATUS  CHANNEL TESTS  CHANNEL 1(2) LOST PACKETS
: "Yes"
: "Fail"
: "Disabled"
: "OK"
: "n/a"
: "OK"
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 9: COMMISSIONING
: "2"
: "OK"
: "1"
: "2"
: "OK"
ACTUAL VALUES  STATUS 
: "Fail"