Current Differential - GE L30 Instruction Manual

10 COMMISSIONING
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 and both relays track frequency. Wait
200 seconds and verify the following:

ACTUAL VALUES STATUS

ACTUAL VALUES METERING
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.
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 and 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
current below the breakpoint is given by the following formula, where P is the pickup setting and S
setting (in decimal format):
• 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
current below breakpoint is given by the following formula:
where TAP represents the CT Tap setting for the corresponding channel.
• Repeat the above test for different slope and pickup settings, if desired.
• During the tests, observe the current phasor at
This phasor should also be seen at
with a phasor of twice the magnitude at
• Repeat the above tests for Phases B and C.
• Restore the communication circuits to normal.
Download the UR Test software from the GE Grid Solutions website
port/ur/l90test.zip) or contact GE Grid Solutions for information about the UR current differential test program which
allows the user to simulate different operating conditions for verifying correct responses of the relays during com-
NOTE
missioning activities.
GE Multilin
 
CHANNEL TESTS PFLL STATUS:

TRACKING FREQUENCY
I 2 × ------------------ -
=
op
1 2S
2P
I ------------------------------------------------------------------------- -
=
op
2
( 1 TAP ) 2S
+ –
ACTUAL VALUES
ACTUAL VALUES
ACTUAL VALUES
L30 Line Current Differential System
"OK"
 actual frequency at both relays
TRACKING FREQUENCY:

10.1.3 CURRENT DIFFERENTIAL

2
P
2
–
1
2
2 2
( 1 TAP )
+
1
 
METERING
 
METERING 87L DIFF CURRENT
 
METERING 87L DIFF CURRENT
(http://www.gegridsolutions.com/products/sup-
10.1 TESTING
is the Slope 1
1
(EQ 10.1)
(EQ 10.2)

87L DIFF CURRENT LOCAL IA
 along
TERMINAL 1(2) IA
.

IA DIFF
10-3
.
10