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Powerpact and Masterpact circuit breakers with advanced Micrologic trip units
Electrical distribution systems
ZSI is an interlocking system used to enhance the selective coordination level of electrical distribution systems. It allows an upstream breaker to trip instantaneously on a fault in its zone while maintaining coordination with downstream breakers.
The attached data bulletin will answer most questions related to the use of Zone Selective Interlocking on Schneider Electric circuit breakers.