To use the ZSI function between 2 Compact NSX MCCBs; one in the upstream and the other in the downstream, one of them will have to be a Compact NSX400~630 to contain the terminals Z3, Z4 and Z5. These terminals are the ones to which the downstream MCCB should be connected to. Compact NSX100~250 MCCBs do not contain these terminals (Z3, Z4 and Z5) and thus won't be able to perform the ZSI function if placed in the upstream/downstream combinations. Please refer to the attached pages from the Micrologic trip unit user manual (refer to "Extract - Compact NSX - Micrologic 5 or 6 - User manual.pdf"). So to make use of the ZSI function between 2 Compact NSX MCCBs, please make that the upstream breaker is Compact NSX400~630.

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