CHAPTER 8: COMMISSIONING
DIFFERENTIAL CHARACTERISTIC TEST EXAMPLES
T35 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
8-7
8
2.
Read the following differential and restraint current values from the T35 actual values menu.
The Percent Differential element does not operate even though I
d
is larger than the Minimum Pickup, because I
d
is not
large enough to make the I
d
/I
r
ratio larger than the Slope 1 setting of 15%. The actual ratio is 11.3%.
3.
Adjust the I
1
current as follows (thereby increasing I
d
) and verify that the element operates.
4.
Read the following differential and restraint current values in the T35 actual values menu.
5.
The actual I
d
/I
r
ratio is now 17%. Verify that the element operates correctly.
8.2.2.5 Intermediate curve between Breakpoint 1 and Breakpoint 2
This procedure tests the intermediate section of the differential characteristic curve that lies between the Breakpoint 1 and
Breakpoint 2 points (points B
1
and B
2
on the Differential Restraint Characteristic diagram).
1.
Inject currents so that the magnitude of I
r
is between the restraint magnitudes defined by Breakpoint 1 and
Breakpoint 2; that is:
I
r
(at Breakpoint 1) > I
r
< I
r
(at Breakpoint 2)
Eq. 8-10
For this example, 2 pu < I
r
< 8 pu. Remember that the maximum current is the restraint current I
r
= 3.5 pu.
2.
Read the following differential and restraint current values from the T35 actual values menu.
The I
d
/I
r
ratio is 36.77% and the Differential element does not operate because the actual I
d
= 1.287 pu is still too low
at I
r
= 3.5 pu.
Phase
Differential current (I
d
)
Phase
Restraint current (I
r
)
A
0
∠
0°
A
0
∠
0°
B
0.113 pu
∠
0°
B
1 pu
∠
–180°
C
0.113 pu
∠
0°
C
1 pu
∠
0°
Winding 1
Winding 2
Phase
Single current (I
1
)
Phase
Single current (I
2
)
A
0 A
∠
0°
A
0 A
∠
0°
B
0.45 A
∠
0°
B
1 A
∠
–180°
C
0.45 A
∠
–180°
C
1 A
∠
0°
Phase
Differential Current (I
d
)
Phase
Restraint current (I
r
)
A
0
∠
0°
A
0
∠
0°
B
0.170 pu
∠
0°
B
1 pu
∠
–180°
C
0.170 pu
∠
0°
C
1 pu
∠
0°
Winding 1
Winding 2
Phase
Single current (I
1
)
Phase
Single current (I
2
)
A
0 A
∠
0°
A
0 A
∠
0°
B
1.2 A
∠
0°
B
3.5 A
∠
–180°
C
1.2 A
∠
–180°
C
3.5 A
∠
0°
Phase
Differential current (I
d
)
Phase
Restraint current (I
r
)
A
0
∠
0°
A
0
∠
0°
B
1.287 pu
∠
–180°
B
3.5 pu
∠
–180°
C
1.287 pu
∠
0°
C
3.5 pu
∠
0°
Содержание T35
Страница 9: ...TABLE OF CONTENTS T35 TRANSFORMER PROTECTION SYSTEM INSTRUCTION MANUAL ix ABBREVIATIONS INDEX ...
Страница 10: ...x T35 TRANSFORMER PROTECTION SYSTEM INSTRUCTION MANUAL TABLE OF CONTENTS ...
Страница 14: ...1 4 T35 TRANSFORMER PROTECTION SYSTEM INSTRUCTION MANUAL FOR FURTHER ASSISTANCE CHAPTER 1 INTRODUCTION 1 ...
Страница 202: ...4 88 T35 TRANSFORMER PROTECTION SYSTEM INSTRUCTION MANUAL FLEXLOGIC DESIGN USING ENGINEER CHAPTER 4 INTERFACES 4 ...
Страница 472: ...5 270 T35 TRANSFORMER PROTECTION SYSTEM INSTRUCTION MANUAL TESTING CHAPTER 5 SETTINGS 5 ...
Страница 500: ...6 28 T35 TRANSFORMER PROTECTION SYSTEM INSTRUCTION MANUAL PRODUCT INFORMATION CHAPTER 6 ACTUAL VALUES 6 ...
Страница 514: ...7 14 T35 TRANSFORMER PROTECTION SYSTEM INSTRUCTION MANUAL TARGETS MENU CHAPTER 7 COMMANDS AND TARGETS 7 ...
Страница 580: ...A 16 T35 TRANSFORMER PROTECTION SYSTEM INSTRUCTION MANUAL FLEXANALOG ITEMS APPENDIX A FLEXANALOG OPERANDS A ...
Страница 588: ...C 6 T35 TRANSFORMER PROTECTION SYSTEM INSTRUCTION MANUAL COMMAND LINE INTERFACE APPENDIX C COMMAND LINE INTERFACE C ...
Страница 596: ...iv T35 TRANSFORMER PROTECTION SYSTEM INSTRUCTION MANUAL ABBREVIATIONS ...