Description
2.5 Protection functions
3VA molded case circuit breakers with UL and IEC certification
76
Manual, 01/2019, L1V30435333-01
2.5.9
Zone-selective interlocking ZSI
The microprocessor-controlled, zone-selective interlocking function has been developed in
order to control the total breaking time in low-voltage networks with multiple molded case
circuit breakers connected in series.
Regardless of the number of series-connected molded case circuit breakers, all short circuits
in the network greater than I
st
but less than I
i
will have a delay of no more than 50 ms.
Note
Backward compatibility
The ZSI function of 3VA UL molded case circuit breakers is compatible with the ZSI
functions of Siemens 3VL molded case circuit breakers and 3WL air circuit breakers.