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3
Operation
Theory
PCS-978 Transformer Relay
3-76
Date: 2013-01-16
AC1
AC2
Zs1
Zs2
Shunt reactor 1
Shunt reactor 2
Zr2
Z
L
F1
F2
R
e
la
y
2
Zr1
R
e
la
y
1
Figure 3.6-1 Wiring diagram of shunt reactors in power system
Where:
AC1, AC2 : equivalent voltage source.
Zs1, Zs2: equivalent system impedance.
Zr1, Zr2 : impedance of shunt reactor.
Z
L
: line impedance.
F1: fault point 1
F2: fault point 2
1) Case 1: External single-phase earth fault of line (close-up external earth fault at F1)
The fault point is zero sequence source, the equivalent zero-sequence network is shown below.
Zr2
U0
Fault PS
Zs
′
I0
Figure 3.6-2 Equivalent zero-sequence network for case 1
Where
:
Zs
'
: equivalent system impedance, Zs
'
=(Zr1//Zs1+ ZL)//Zs2
U0: relay detected zero sequence voltage
I0: relay detected zero sequence current
FaultPS: fault power source
It is an external earth fault, so viewing from reactor relay location, zero-sequence current flows to
reactor from reactor grounding point and via transmission line back to the ground at the earth fault
point. Therefore, the equation between U0 and I0 at the relay location is:
U0=I0xZr2
Vector relation between U0 and I0 is:
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 ...