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3 Operation Theory
PCS-978 Transformer Relay
3-35
Date: 2013-01-16
instantaneous differential protection and DPFC biased differential protection. Biased differential
protection is two-slope differential protection with biased characteristic. Unrestrained differential
protection is to accelerate the operating speed for reactor’s severe internal faults without biased
characteristic and blocking elements. DPFC biased differential protection calculated by current
variation has high sensitivity to earth faults at ground end of reactor. Above three differential
protection elements work coordinately to form the high-speed current differential protection with
high sensitivity.
3.3.3.2 Fault Detector
Fault detector of biased differential current
The pickup of this fault detector will enable the biased differential protection, and its operation
equation is as follows.
d
I
[87R.I_Biased]
Equation 3.3-1
Where
:
d
I
is the differential current of any phase.
[87R.I_Biased] is the pickup current of biased differential protection.
Fault detector of instantaneous differential protection
The pickup of this fault detector will enable the unrestrained instantaneous differential protection,
and its operation equation is as follows.
d
I
0.9x[87R.I_Instant]
Equation 3.3-2
Where
:
d
I
is the differential current of any phase.
[87R.I_Instant] is the setting of the unrestrained instantaneous differential protection.
Fault detector of DPFC differential current
The pickup of this fault detector will enable the DPFC biased differential protection, and its
operation equation is as follows.
2
1
25
.
1
I
I
I
I
I
I
d
dth
dt
d
Equation 3.3-3
Where:
d t
I
is the floating threshold varied with the change of load current from time to time. The change
Содержание PCS-978
Страница 1: ...PCS 978 Transformer Relay Instruction Manual NR Electric Co Ltd ...
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Страница 6: ...Preface PCS 978 Transformer Relay IV Date 2013 01 16 ...
Страница 10: ...Preface PCS 978 Transformer Relay VIII Date 2013 01 16 ...
Страница 62: ...3 Operation Theory PCS 978 Transformer Relay 3 p Date 2013 01 16 ...
Страница 250: ...4 Supervision PCS 978 Transformer Relay 4 b Date 2013 01 16 ...
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Страница 266: ...5 Management PCS 978 Transformer Relay 5 b Date 2013 01 16 ...
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Страница 370: ...8 Human Machine Interface PCS 978 Transformer Relay 8 d Date 2013 01 16 ...
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Страница 406: ...9 Configurable Function PCS 978 Transformer Relay 9 b Date 2013 01 16 ...
Страница 446: ...10 Communication PCS 978 Transformer Relay 10 26 Date 2013 01 16 ...
Страница 448: ...11 Installation PCS 978 Transformer Relay 11 b Date 2012 10 09 ...
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