3
Operation
Theory
PCS-978 Transformer Relay
3-106
Date: 2013-01-16
I
is the deviation value of phase-to-phase current.
th
I
is the fixed threshold of 0.2 In and does not need to be set on site.
Fault detector of negative-sequence current
Criteria of this fault detector:
2
I
0.2In
Equation 3.11-2
Where:
2
I
is the negative-sequence current of some side.
In is the secondary rated current of CT.
3.11.3.3 Phase-to-Phase Impedance Protection
Following figure shows operating characteristic of phase-to-phase impedance relay with relay
characteristic angle (RCA) [21.RCA] (i.e.
m
shown in the following figure, also called reach
angle). In this figure, Zn is the reverse impedance setting [x.21.ZP1(2).Z_Fwd] (pointing to
system direction) and Zp is the forward impedance setting [x.21.ZP1(2).Z_Rev] (pointing to
transformer direction).
p
Z
jx
R
m
n
Z
Figure 3.11-1 Operating characteristic of phase-to-phase impedance relay
The operation criterion of phase-to-phase impedance relay is as follows.
270
)
(
)
(
90
n
P
Z
I
U
Z
I
U
Arg
Equation 3.11-3
NOTE!
If VT circuit abnormal message [x.Alm_VTS] is issued or VT is out of service,
impedance protection will be blocked.
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 ...