Frequently asked questions
What is zone selective interlocking (ZSI)?
FA93330
23 May 2022
Issue:What is ZSI?
Product Line:
Molded Case Circuit Breakers
Resolution:
Zone selective interlocking (ZSI): a communication capability between electronic trip systems and ground fault relays that permits a short circuit or ground fault to be isolated and cleared by the nearest upstream device with no intentional time delay.