3
Operation
Theory
PCS-978 Transformer Relay
3-136
Date: 2013-01-16
3.14.2 Function
Negative-sequence overcurrent protection has following functions:
Two-stage negative-sequence overcurrent protection with independent logic, current and
time delay settings.
Stage 1 is definite-time characteristic, stage 2 can be selected as definite-time or
inverse-time characteristic. The inverse-time characteristic is selectable, among IEC and
ANSI/IEEE standard inverse-time characteristics and a user-defined inverse-time curve.
3.14.3 Protection Principle
3.14.3.1 Operation Criterion
The operation criterion of stage 1 negative-sequence overcurrent protection is:
2
I
>[x.50/51Q1.I2_Set]
Equation 3.14-1
Where:
2
I
is negative-sequence current of x side..
[x.50/51Q1.3I0_Set] is the current setting of stage 1 of negative-sequence overcurrent protection
of x side.
If negative-sequence current is greater than the setting of the stage enabled negative-sequence
overcurrent protection, the stage protection will operate after time delay, and the stage protection
will drop off instantaneously after fault current disappears.
3.14.3.2 Time Curve
Negative-sequence overcurrent protection stage 1 is definite-time characteristic and can perform
instantaneous operation with the corresponding time delay setting at zero. Stage 2 can be
selected as definite-time or inverse-time characteristic, and inverse-time operating time curve is as
follows.
P
set
T
C
)
I
I
(
K
t(I)
1
Equation 3.14-2
Where:
set
I
is negative-sequence current setting [x.50/51Q2.I2_Set].
p
T
is time multiplier setting [x.50/51Q2.TMS].
K
, C are constants.
Summary of Contents for PCS-978
Page 1: ...PCS 978 Transformer Relay Instruction Manual NR Electric Co Ltd ...
Page 2: ......
Page 6: ...Preface PCS 978 Transformer Relay IV Date 2013 01 16 ...
Page 10: ...Preface PCS 978 Transformer Relay VIII Date 2013 01 16 ...
Page 62: ...3 Operation Theory PCS 978 Transformer Relay 3 p Date 2013 01 16 ...
Page 250: ...4 Supervision PCS 978 Transformer Relay 4 b Date 2013 01 16 ...
Page 264: ...4 Supervision PCS 978 Transformer Relay 4 14 Date 2013 01 16 ...
Page 266: ...5 Management PCS 978 Transformer Relay 5 b Date 2013 01 16 ...
Page 272: ...5 Management PCS 978 Transformer Relay 5 6 Date 2013 01 16 ...
Page 334: ...6 Hardware Description PCS 978 Transformer Relay 6 60 Date 2013 01 16 ...
Page 370: ...8 Human Machine Interface PCS 978 Transformer Relay 8 d Date 2013 01 16 ...
Page 404: ...8 Human Machine Interface PCS 978 Transformer Relay 8 34 Date 2013 01 16 ...
Page 406: ...9 Configurable Function PCS 978 Transformer Relay 9 b Date 2013 01 16 ...
Page 446: ...10 Communication PCS 978 Transformer Relay 10 26 Date 2013 01 16 ...
Page 448: ...11 Installation PCS 978 Transformer Relay 11 b Date 2012 10 09 ...
Page 456: ...11 Installation PCS 978 Transformer Relay 11 8 Date 2012 10 09 ...
Page 458: ...12 Commissioning PCS 978 Transformer Relay 12 b Date 2012 12 07 ...
Page 468: ...12 Commissioning PCS 978 Transformer Relay 12 10 Date 2012 12 07 ...
Page 470: ...13 Maintenance PCS 978 Transformer Relay 13 b Date 2012 10 09 ...
Page 474: ...13 Maintenance PCS 978 Transformer Relay 13 4 Date 2012 10 09 ...
Page 476: ...14 Decommissioning and Disposal PCS 978 Transformer Relay 14 b Date 2012 10 09 ...
Page 478: ...14 Decommissioning and Disposal PCS 978 Transformer Relay 14 2 Date 2012 10 09 ...
Page 480: ...15 Manual Version History PCS 978 Transformer Relay 15 2 Date 2013 01 16 ...