Siemens UL 489 Operating Instructions Manual page 190

Terminal assignment
Terminal Connection
Only for Tie Breakers;
TIE BRKR
Allows complete ZSI functionality in systems with tie breakers
ZSI IN ZSI modules of downstream circuit breakers
ZSI OUT ZSI modules of upstream circuit breakers
MV OUT Signal to the medium-voltage level
Observe the specified polarity when connecting: plus to plus and minus to minus.
The maximum wire length of the ZSI wiring is 400 m for a wire diameter of AWG 18 (2-wire conductor).
For ZSI connections between only WL circuit breakers, wire lengths of up to 1000 m are permissible if the conductor diameter is increased
to AWG 13.
The ZSI connections must consist of twisted pair cables or shielded cables.
The ZSI module allows connection of up to:
- 8 circuit breakers at the ZSI IN input and
- 20 circuit breakers at the ZSI OUT output
Note: Prior to testing the circuit breaker via primary injection and while 24v dc is applied to the trip unit and ZSI module, turn the rotary
switch to OFF. If this is not done, the trip unit will "remember" being part of the ZSI system and will always trip according to its ZSI time
(80ms) during a short-time overcurrent test instead of in its set delay.
Be sure to turn ZSI back on prior to re-energizing the system.
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