SELF-SOURCING, ISOLATED ZONE SELECTIVE INTERLOCKING SYSTEM FOR USE WITH ELECTRONIC TRIP CIRCUIT BREAKERS

摘要

A zone selective interlocking system for electronic trip circuit breakers includes a plurality of downstream terminals, each downstream terminal connecting with at least one of a plurality of downstream electronic trip circuit breakers having input terminals. A restraint input circuit module, including a voltage comparator, is connected to the input terminals of each of the downstream electronic trip circuit breakers and the input terminals are shorted together providing a self-restraint signal for each downstream electronic trip circuit breaker at the occurrence of a downstream fault condition. The system also includes a plurality of upstream terminals, each upstream terminal connecting with at least one of a plurality of upstream electronic trip circuit breakers havint input terminals. The restraint input circuit module is connected to the input terminals of each of the upstream electronic trip circuit breakers for receiving a signal indicative of the downstream fault condition and wherein the restraint input circuit module is self-sourcing. An output circuit module including an opto-isolator is connected to each of the upstream electronic trip circuit breakers and each of the downstream electronic trip circuit breakers for providing galvanic isolation between circuit breakers in a restrained mode and circuit breakers in an unrestrained mode.