Functions
2.3 Overcurrent protection (optional)
SIPROTEC, 7VK61, Manual
C53000-G1176-C159-3, Release date 05.2009
70
End fault protection
A further overcurrent stage is the stub protection. It can however also be used as a normal additional definite
time overcurrent stage, as it functions independent of the other stages.
A stub fault is a short-circuit located between the current transformer set and the line isolator. It is of particular
importance with the 1
1
/
2
circuit breaker arrangements.
Figure 2-14
Stub fault at an 1
1
/
2
circuit breaker arrangement
If a short circuit current
I
A
and/or
I
B
flows while the line isolator 1 is open, this implies that a fault in the stub
range between the current transformers
I
A
,
I
B
, and the line isolator exists. The circuit breakers CBA and CBC
that carry the short-circuit current can be tripped without delay. The two sets of current transformers are con-
nected in parallel such that the current sum
I
A
+
I
B
represents the current flowing towards the line isolator.
The stub protection is an overcurrent protection which is only in service when the state of the line isolator indi-
cates the open condition via a binary input
„>I-STUB ENABLE“
. The binary input must therefore be operated
via an auxiliary contact of the isolator. In the case of a closed line isolator, the stub protection is out of service.
For more information see the next logic diagram.
If the stub protection stage is to be used as a normal definite time overcurrent stage, the binary input
„>BLOCK
I-STUB“
, should be left without allocation or routing (matrix). The enable input
„>I-STUB ENABLE“
, however,
has to be constantly activated (either via a binary input or via integrated logic (CFC) functions which can be
configured by the user.
Summary of Contents for Siprotec 7VK61
Page 8: ...Preface SIPROTEC 7VK61 Manual C53000 G1176 C159 3 Release date 05 2009 8 ...
Page 14: ...Contents SIPROTEC 7VK61 Manual C53000 G1176 C159 3 Release date 05 2009 14 ...
Page 316: ...Literature SIPROTEC 7VK61 Manual C53000 G1176 C159 3 Release date 05 2009 316 ...
Page 328: ...Glossary SIPROTEC 7VK61 Manual C53000 G1176 C159 3 Release date 05 2009 328 ...