# Current Differential - GE UR Series Instruction Manual

Line differential relay.

10 COMMISSIONING
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 will not affect PFLL when only one relay has a current input. Wait 200 sec. and verify the following:
ACTUAL VALUES / STATUS / CHANNEL TESTS / PFLL STATUS:
ACTUAL VALUES / METERING / TRACKING FREQUENCY:
For 3-terminal configuration, the above-indicated tests should be carried out accordingly.
NOTE
The 87L element has adaptive restraint and dual slope characteristics. The pickup slope settings and the breakpoint set-
tings determine the element characteristics. The relay displays both local and remote current magnitudes and angles and
the differential current which helps with start-up activities.
When a differential condition is detected, the output operands from the element will be asserted along with energization of
faceplate event indicators.
TEST PROCEDURE:
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:
•Ensure that all 87L setting are properly entered into the relay.
•Connect a test set to the relay to inject current into phase A.
•Slowly increase the current until the relay operates, and note the pickup value. The theoretical value of operating cur-
rent below the breakpoint is given by the following formula, where P is the pickup setting and S
ting (in decimal format):
P
×
I
=
2
-------------------
op
1 2 S
•Repeat the above test for different slope and pickup settings, if desired.
•Repeat the above tests for phases B and C.
4.
Minimum pickup test with local current and simulated remote current (pure internal fault simulation):
•Disconnect the local relay from the communications channel.
•Loop back the transmit signal to the receive input on the back of the relay.
•Wait until the CHANNEL and PFLL status displays indicate OK.
•Slowly increase the current until the relay operates and note the pickup value. The theoretical value of operating cur-
rent below breakpoint is given by the following formula:
2
P
I
=
----------------------- -
op
(
2 1 S
•Repeat the above test for different slope and pickup settings, if desired.
•During the tests observe that the current phasor at
phasor should also be displayed at
twice the magnitude should be displayed at
•Repeat the above tests for phases B and C.
•Restore the communication circuits to normal.
GE Power Management
"50 Hz" or "60 Hz" (nominal)
2
2
1
2
)
1
ACTUAL VALUES / METERING / 87L DIFF CURRENT / LOCAL IA
ACTUAL VALUES / METERING / 87L DIFF CURRENT / TERMINAL 1(2) IA
ACTUAL VALUES / METERING / 87L DIFF CURRENT / IA DIFF
L90 Line Differential Relay
10.9 L90 COMMISSIONING TESTS
"OK"
"n/a"
"OK"
"OK"

## 10.9.3 CURRENT DIFFERENTIAL

is the slope 1 set-
1
. This
. A phasor of
.
10
10-45