Purpose
Three phase monitor CZF-312 serve to protect the  three-phase electric motors supplied from three-phase mains, against phase collapse in at least one phase or against phase-to-phase voltage asymmetry, threatening to damage the motor.

Functioning
Phase collapse in at least one phase or voltage unbalance  between phases above set value causes switching-OFF the motor. The  motor switching-OFF occurs with 0,3 sec delay, which prevents any accidental motor disconnecting at temporary voltage drop. The re-connection will occur automatically at voltage increase of 5V above activation voltage (i.e. of value of voltage hysteresis). At occurrence of these disturbances, it is not possible to set a motor in motion.