GE Multilin
T60 Transformer Protection System
9-13
9 COMMISSIONING
9.3 INRUSH INHIBIT TEST
9
9.3INRUSH INHIBIT TEST
9.3.1 INRUSH INHIBIT TEST PROCEDURE
The Inrush Inhibit Test requires a secondary injection test capable of producing a current with an adjustable second
harmonic component. Use the appropriate commissioning tables at the end of this chapter to record values.
This procedure is based upon the example provided in the Differential Characteristic Test Example section. The trans-
former parameters are as follows:
Transformer: Y/y0°, 230/69 kV, CT1 (300:1), CT2 (1000:1)
2nd Harmonic Setting = 20%
1.
Connect the relay test set to inject current into the Winding 1 Phase A CT input.
2.
Inject currents into the relay as shown in the table below until the biased differential element picks up.
3.
Confirm that only the percent differential element has operated.
4.
Increase the harmonic content until the element drops out. Record this value as the
Inrush Inhibit Level Pickup
.
5.
Gradually decrease the harmonic content level until the element picks up. Record this value as the
Inrush Inhibit
Level Dropout
.
6.
Switch off the current.
7.
Repeat steps 1 through 6 for phases B and C.
8.
Repeat steps 1 through 7 for Winding 2 (and Windings 3 and 4 if necessary).
The second harmonic inhibit feature can be verified by setting the
INRUSH INHIBIT MODE
setting as follows:
For
INRUSH INHIBIT MODE
set to "2-out-of-3":
1.
Set the
INRUSH INHIBIT FUNCTION
to "Trad. 2nd" and the
INRUSH INHIBIT LEVEL
to "20%".
2.
Inject currents into one CT bank (one winding only) until the biased differential operates for all three phases.
3.
Apply a second harmonic to Phase A higher than the set threshold and monitor operation of Phases A, B, and C. The
element should stay operated on all three phases.
4.
Apply a second harmonic to Phase B with a level less than the set threshold.
5.
Increase the second harmonic level in Phase B. When it passes the set threshold, all three phases of differential pro-
tection should drop out.
For
INRUSH INHIBIT MODE
set to "Average":
1.
Set the
INRUSH INHIBIT FUNCTION
to "Trad. 2nd" and the
INRUSH INHIBIT LEVEL
to "20%".
2.
Inject currents into one CT bank (one winding only) until the biased differential operates for all three phases.
3.
Apply a second harmonic to Phase A with a level greater than the set threshold and monitor the operation of the Per-
cent Differential element. The element should drop out when the injected second harmonic level becomes three times
larger than the set threshold.
Table 9–1: INRUSH INHIBIT TEST SUMMARY
PHASE
INJECTED
DISPLAYED
STATUS
W1
CURRENT
W1 2ND
HARMONIC
W2
CURRENT
W2 2ND
HARMONIC
I
d
2ND
HARMONIC
I
r
A
1 A
∠
0°
18.01%
0 A
∠
0°
0
0.997 pu
18%
0.997 pu
Operate
1 A
∠
0°
19.97%
0 A
∠
0°
0
0.997 pu
20%
0.997 pu
Block
B
4 A
∠
0°
16.72%
2 A
∠
–180°
15%
2 pu
18%
4 pu
Operate
4 A
∠
0°
17.60%
2 A
∠
–180°
15%
2 pu
20%
4 pu
Block
C
2 A
∠
0°
15%
4 A
∠
–180°
16.3%
2 pu
18%
4 pu
Operate
2 A
∠
0°
15%
4 A
∠
–180°
17.3%
2 pu
20%
4 pu
Block
NOTE
Summary of Contents for T60
Page 6: ...vi T60 Transformer Protection System GE Multilin TABLE OF CONTENTS ...
Page 14: ...xiv T60 Transformer Protection System GE Multilin TABLE OF CONTENTS ...
Page 34: ...1 20 T60 Transformer Protection System GE Multilin 1 5 USING THE RELAY 1 GETTING STARTED 1 ...
Page 490: ...5 344 T60 Transformer Protection System GE Multilin 5 10 TESTING 5 SETTINGS 5 ...
Page 522: ...6 32 T60 Transformer Protection System GE Multilin 6 5 PRODUCT INFORMATION 6 ACTUAL VALUES 6 ...
Page 536: ...7 14 T60 Transformer Protection System GE Multilin 7 1 COMMANDS 7 COMMANDS AND TARGETS 7 ...
Page 568: ...10 12 T60 Transformer Protection System GE Multilin 10 6 DISPOSAL 10 MAINTENANCE 10 ...
Page 596: ...A 28 T60 Transformer Protection System GE Multilin A 1 PARAMETER LISTS APPENDIX A A ...
Page 716: ...B 120 T60 Transformer Protection System GE Multilin B 4 MEMORY MAPPING APPENDIX B B ...
Page 762: ...E 10 T60 Transformer Protection System GE Multilin E 1 IEC 60870 5 104 PROTOCOL APPENDIX E E ...
Page 774: ...F 12 T60 Transformer Protection System GE Multilin F 2 DNP POINT LISTS APPENDIX F F ...