Accessories
4.10 EFB300 external function box
3VA molded case circuit breakers with IEC certificate
Manual, 03/2019, A5E03603177010-03
499
Default output assignments
The four outputs of the EFB300 are automatically assigned factory defaults in ETUs with
firmware version 4.2 and higher.
4.10.4
Zone selective interlocking (ZSI)
Description
Microprocessor-controlled, zone selective interlocking (ZSI) has been developed in order to
control the total breaking time in low-voltage networks with multiple molded case circuit
breakers connected in series.
Advantage of ZSI:
Regardless of the number of series-connected molded case circuit breakers, all short circuits
in the network can be cleared within a maximum time period of 50 ms. Short-circuit
clearance times should be minimized, particularly in the case of system short circuits of very
large magnitude.
Note
Backward compatibility
The ZSI function is backward-compatible with the ZSI function of the 3WL molded case
circuit breakers.
