Siemens SENTRON 3VA1 Manual page 502

Accessories
4.10 EFB300 external function box
Connection
Use of the ZSI function is conditional upon the connection of a dedicated EFB300 external
function box to each 3VA2 molded case circuit breaker. The EFB300 allows molded case
circuit breakers to communicate with one another, a capability which is a basic requirement
for the ZSI function.
To permit utilization of the ZSI function, EFB300 external function boxes must be
interconnected as illustrated below:
See also
Zone selective interlocking (ZSI) (Page 82)
500
3VA molded case circuit breakers with IEC certificate
Manual, 03/2019, A5E03603177010-03