Siemens SIPROTEC 4 7VK61 Manual page 72

Functions
2.3 Overcurrent protection (optional)
[endfehler-eineinhalb-ls-wlk-0702, 1, en_GB]
Figure 2-18
If a short circuit current Ι
range between the current transformers Ι
that carry the short-circuit current can be tripped without delay. The two sets of current transformers are
connected in parallel such that the current sum Ι
The stub protection is an overcurrent protection which is only in service when the state of the line isolator
indicates the open condition via a binary input
ated 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
I-STUB should be left without allocation or routing (matrix). However the release input >I-STUB ENABLE
must be continually activated (either via a binary input or via the user definable logic functions CFC).
72
Stub fault at an 1 1 / circuit breaker arrangement
2
and/or Ι flows while the line isolator 1 is open, this implies that a fault in the stub
A B
, Ι
A
and the line isolator exists. The circuit breakers CBA and CBC
B
+ Ι represents the current flowing towards the line isolator.
A B
>I-STUB ENABLE . The binary input must therefore be oper-
SIPROTEC 4, 7VK61, Manual
C53000-G1176-C159-5, Edition 05.2018
>BLOCK