5-236
T60 Transformer Protection System
GE Multilin
5.6 GROUPED ELEMENTS
5 SETTINGS
5
c) NEUTRAL INSTANTANEOUS OVERCURRENT
(ANSI 50N, IEC PIOC)
PATH: SETTINGS
GROUPED ELEMENTS
SETTING GROUP 1(6)
NEUTRAL CURRENT
NEUTRAL IOC1(12)
The neutral instantaneous overcurrent element may be used as an instantaneous function with no intentional delay or as a
definite time function. The element essentially responds to the magnitude of a neutral current fundamental frequency pha-
sor calculated from the phase currents. A positive-sequence restraint is applied for better performance. A small portion
(6.25%) of the positive-sequence current magnitude is subtracted from the zero-sequence current magnitude when forming
the operating quantity of the element as follows:
(EQ 5.37)
The positive-sequence restraint allows for more sensitive settings by counterbalancing spurious zero-sequence currents
resulting from
•
System unbalances under heavy load conditions
•
Transformation errors of current transformers (CTs) during double-line and three-phase faults
•
Switch-off transients during double-line and three-phase faults
The positive-sequence restraint must be considered when testing for pickup accuracy and response time (multiple of
pickup). The operating quantity depends on how test currents are injected into the relay (single-phase injection):
(EQ 5.38)
NEUTRAL IOC1
NEUTRAL IOC1
FUNCTION: Disabled
Range: Disabled, Enabled
MESSAGE
NEUTRAL IOC1 SIGNAL
SOURCE: SRC 1
Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6
MESSAGE
NEUTRAL IOC1
PICKUP: 1.000
pu
Range: 0.000 to 30.000 pu in steps of 0.001
MESSAGE
NEUTRAL IOC1 PICKUP
DELAY: 0.00
s
Range: 0.00 to 600.00 s in steps of 0.01
MESSAGE
NEUTRAL IOC1 RESET
DELAY: 0.00
s
Range: 0.00 to 600.00 s in steps of 0.01
MESSAGE
NEUTRAL IOC1 BLOCK:
Off
Range: FlexLogic operand
MESSAGE
NEUTRAL IOC1
TARGET: Self-reset
Range: Self-reset, Latched, Disabled
MESSAGE
NEUTRAL IOC1
EVENTS: Disabled
Range: Disabled, Enabled
I
op
3
I_0
K
x
I_1
–
(
)
×
=
where
K
1 16
⁄
=
I
op
1
3
---
3
K
–
(
)
×
x
I
injected
=
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 ...