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3
Operation
Theory
PCS-978 Transformer Relay
3-14
Date: 2013-01-16
3.2.3.9 Operation Characteristic of Biased and Instant Differential Protections
The characteristic of internal faults is a straight line with the slope 2 (63.4°) in the operation
diagram (dash-dotted line K=2)
Restraint current
KP1
KP2
0.8
Ir (pu)
0
[87T.I_Biased]
Id (pu)
1.2
Differential
current
[87
T.S
lop
e2
]
[87T.I_Instant]
Tr
ip
pi
ng
a
re
a
of
se
ns
iti
ve
b
ia
se
d
D
iff
.
Tr
ip
pi
ng
a
re
a
of
co
nv
en
tio
na
l b
ia
se
d
D
iff
.
Tripping area of
instantaneous Diff.
K
=
2
[8
7.
S
lo
pe
3]
K=
0.
6
A
B
C
[87T
.Slop
e1]
D
E
F
Figure 3.2-4 Operation characteristic curve of biased and instant differential protections for transformer
In above figure:
KP1, KP2 are respectively X-axis values of knee point 1 and knee point 2, i.e. [87T.I_Knee1] and
[87T.I_Knee2].
A is the point shows normal operation of transformer.
B is the point shows CT saturation.
C, D, E, and F are points show internal faults or external fault of transformer.
1) Sensitive biased differential protection element will send tripping signal monitored by CT
saturation, overexcitation, inrush current and CT circuit failure (optional). It can ensure
sensitivity of protection and avoid the unwanted operation when CT is saturated during an
external fault. Its operation area is the tint shadow area in the figure above.
When a slight intern fault occurs, differential current rises not greatly and the operating point
moves from A to D into the tripping area of sensitive biased differential protection.
Содержание PCS-978
Страница 1: ...PCS 978 Transformer Relay Instruction Manual NR Electric Co Ltd ...
Страница 2: ......
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 ...
Страница 264: ...4 Supervision PCS 978 Transformer Relay 4 14 Date 2013 01 16 ...
Страница 266: ...5 Management PCS 978 Transformer Relay 5 b Date 2013 01 16 ...
Страница 272: ...5 Management PCS 978 Transformer Relay 5 6 Date 2013 01 16 ...
Страница 334: ...6 Hardware Description PCS 978 Transformer Relay 6 60 Date 2013 01 16 ...
Страница 370: ...8 Human Machine Interface PCS 978 Transformer Relay 8 d Date 2013 01 16 ...
Страница 404: ...8 Human Machine Interface PCS 978 Transformer Relay 8 34 Date 2013 01 16 ...
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 ...
Страница 456: ...11 Installation PCS 978 Transformer Relay 11 8 Date 2012 10 09 ...
Страница 458: ...12 Commissioning PCS 978 Transformer Relay 12 b Date 2012 12 07 ...
Страница 468: ...12 Commissioning PCS 978 Transformer Relay 12 10 Date 2012 12 07 ...
Страница 470: ...13 Maintenance PCS 978 Transformer Relay 13 b Date 2012 10 09 ...
Страница 474: ...13 Maintenance PCS 978 Transformer Relay 13 4 Date 2012 10 09 ...
Страница 476: ...14 Decommissioning and Disposal PCS 978 Transformer Relay 14 b Date 2012 10 09 ...
Страница 478: ...14 Decommissioning and Disposal PCS 978 Transformer Relay 14 2 Date 2012 10 09 ...
Страница 480: ...15 Manual Version History PCS 978 Transformer Relay 15 2 Date 2013 01 16 ...