3WL/3VL circuit breakers with communication capability - PROFIBUS
System Manual, 03/2011, A5E01051353-02
105
Zone Selective Interlocking
5
5.1
ZSI
5.1.1
Introduction
With circuit breakers on several grading levels, the aim is to assign these selectively to each
other so that in the event of an overcurrent only the circuit breaker immediately upstream
switches off the overcurrent.
5.1.2
Selectivity
A plant with several protective devices switched in series is selective only if the protective
device immediately in front of the fault location picks up in the event of an overcurrent and
switches off the overcurrent alone. Branches not affected continue to be supplied.