Methods of implementing selectivity using circuit breakers
3.5 Zone selective interlocking
Selectivity for 3VA molded case circuit breakers
Configuration Manual, 08/2016, A5E03603181010-01
31
Signal output
E Signal input
- - - Control wires
t
sd
Delay time setting for the short-circuit release
t
ZSI
Delay time (defined non-operation time) of all breakers that detect the short-circuit and/or
ground fault current and do not receive a "block" signal when ZSI is activated
Figure 3-9 Zone selective interlocking
The tripping delays that can be implemented with zone selective interlocking are normally
shorter than those achievable with time selectivity, even though selectivity still remains
operative.
The control wires for the electronic trip units are connected to a separate communication
module that is provided for each circuit breaker.
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