9-2
T60 Transformer Protection System
GE Multilin
9.1 DIFFERENTIAL CHARACTERISTIC TEST
9 COMMISSIONING
9
c) SLOPE 1 / BREAKPOINT 1
The point of Slope 1 and Breakpoint 1 is tested as follows. Refer to the Differential Restraint Characteristic diagram below
for details.
1.
Inject current (
I
y
) into Winding 2 Phase A as follows:
(EQ 9.2)
2.
At Breakpoint 1, the injected current
I
XOP
1
is determined by:
(EQ 9.3)
and the differential current should be equal to:
(EQ 9.4)
3.
Preset the
I
x
current to
. Switch on the test set. The relay should restraint, as the differential to restraint
ratio will become less than the Slope 1 setting. Switch off the current.
4.
Preset the
I
x
current to
. Switch on the test set. The relay should operate. Switch off the current.
To test any other point from the Slope 1 section of the curve, inject a per-unit restraint current smaller than the Breakpoint 1
current and repeat the steps above by substituting the Breakpoint 1 value with the new per-unit restraint current value into
the equations above.
d) SLOPE 2 / BREAKPOINT 2
The point of Slope 2 and Breakpoint 2 is tested as follows. Refer to the diagram below for details.
1.
Preset the
I
y
current to a magnitude that results in the restraint current being equal to Breakpoint 2. Use the following
calculation to define the magnitude of the injected current:
(EQ 9.5)
2.
At the above current (restraint), the
I
XOP2
current required to operate the element is calculated as:
(EQ 9.6)
3.
Preset the
I
x
current to
and switch on the test set. The relay should restrain, as the differential to restraint
ratio will become less than the
Slope 2 setting. Switch off the current.
4.
Preset the
I
x
current to
. Switch on the test set and verify relay operation. Switch off the current.
To test any point from the Slope 2 portion of the characteristic, inject a per-unit restraint current greater than the Breakpoint
2 current as restraint and repeat the steps above by substituting the Breakpoint 2 value in the equations above with the new
per-unit restraint current value.
The above two tests can be repeated for Phases B and C.
Figure 9–1: DIFFERENTIAL RESTRAINT CHARACTERISTIC
I
YB
1
Breakpoint 1
CT
M[2]
-----------
×
=
I
XOP
1
Breakpoint 1
1 Slope 1
–
(
)
CT
M[1]
-----------
×
×
=
I
d
Slope 1 (in %) Breakpoint 1 (in pu)
×
=
1.05
I
XOP
1
×
0.95
I
XOP
1
×
I
YB
2
Breakpoint 2
CT
M[2]
-----------
×
=
I
XOP
2
Breakpoint 2
1 Slope 2
–
(
)
CT
M[1]
-----------
×
×
=
1.05
I
XOP
1
×
0.95
I
XOP
1
×
I
d
(pu)
I
r
(pu)
PKP
B
1
S
2
S
1
B
2
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 ...