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3
Operation
Theory
PCS-978 Transformer Relay
3-44
Date: 2013-01-16
3) Unrestrained instantaneous differential protection element will send tripping signal without any
blocking if differential current of any phase reaches its setting. Its operation area is over the
above two areas with the deepest dark shadow.
When a severe internal fault occurs, differential current rises sharply and the operating point
moves to F in the tripping area of instantaneous differential protection.
3.3.3.9 DPFC Biased Differential Protection Element
3.3.3.9.1 DPFC Concept
)
24
(
)
(
k
I
k
I
I
DPFC (Deviation of Power Frequency Component) is the power frequency component of fault
component, which is the differential value between the sampling value at this time point and that at
a cycle before.
)
(
k
I
is the sampling value at the time point.
)
24
(
k
I
is the sampling value at a cycle before, 24 is the sampling points in one cycle.
0
20
40
60
80
100
120
-200
-100
0
100
200
Original Current
0
20
40
60
80
100
120
-100
-50
0
50
100
DPFC current
Figure 3.3-5
Waveform of original current and DPFC current
From above figures, it is concluded that DPFC can reflect the sudden change of fault current at the
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 ...