3
Operation
Theory
PCS-978 Transformer Relay
3-68
Date: 2013-01-16
proportionally. Otherwise, the reference shall be taken as 1, and others will be calculated
proportionally.
The currents used in the following analysis have been corrected, that means the currents for
following calculation are the products of the actual secondary current of each side multiplying its
own correction coefficient (
wph
K
).
3.5.3.4 Calculations of Differential and Restraint Current
The equation of calculating winding differential current is as follows.
5
5
_
2
05
5
5
5
5
4
4
_
2
04
4
4
4
4
3
3
_
2
03
3
3
3
3
2
2
_
2
02
2
2
2
2
1
1
_
2
01
1
1
1
1
0
/
/
/
/
/
CT
n
C
B
A
wph
CT
n
C
B
A
wph
CT
n
C
B
A
wph
CT
n
C
B
A
wph
CT
n
C
B
A
wph
wd
wdC
wdB
wdA
I
I
I
I
I
K
I
I
I
I
I
K
I
I
I
I
I
K
I
I
I
I
I
K
I
I
I
I
I
K
I
I
I
I
Equation 3.5-3
The above equation can be simplified to the following:
05
04
03
02
01
0
5
4
3
2
1
5
4
3
2
1
5
4
3
2
1
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
wd
C
C
C
C
C
wC
B
B
B
B
B
wdB
A
A
A
A
A
wdA
Equation 3.5-4
Where:
wdA
I
wdB
I
wdC
I
0
wd
I
are respectively three phase and residual winding differential currents.
n
Cn
Bn
An
I
I
I
I
0
,
,
,
are respectively secondary values of three phase currents and calculated neutral
current of branch m (m=1, 2, 3, 4 ,5).
n
Cn
Bn
An
I
I
I
I
0
,
,
,
are respectively secondary values of corrected three phase currents and calculated
residual current of branch m (m=1, 2, 3, 4 ,5
)
5
4
3
2
1
,
,
,
,
wph
wph
wph
wph
wph
K
K
K
K
K
are corrected coefficients of each side for magnitude compensation
respectively.
5
_
2
4
_
2
3
_
2
2
_
2
1
_
2
,
,
,
,
CT
n
CT
n
CT
n
CT
n
CT
n
I
I
I
I
I
are respectively rated secondary values of CTs of each
branch.
The equation of calculating restraint current 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 ...