2.11 Overcurrent protection
213
7SA522 Manual
C53000-G1176-C155-3
Figure 2-96 Logic diagram of stub fault protection
Instantaneous Trip-
ping before
Automatic Reclo-
sure
Automatic reclosure is applied in order to instantaneously remove the fault before au-
tomatic reclosure. A release signal from an external automatic reclosure device can
be injected via binary input ´!2&,QVW75,3µ. The internal automatic reclosure - if
available - is also effected by this command. Any stage of the overcurrent protection
can thus perform an instantaneous trip before reclosure via the parameter
7HOHS%,.
Switching onto a
Fault
To achieve fast tripping following manual closure of the circuit breaker onto a dead
fault, the internal line energization detection feature can be used. The overcurrent pro-
tection can then trip three-pole without delay or with a reduced delay. It can be deter-
mined via parameter setting for which stage(s) the rapid tripping following closure on
to a dead fault applies. (Refer also to the logic diagrams in 2-93, 2-94 and 2-96). This
function is independent of the high-current instantaneous tripping described in Sub-
section 2.12.
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