One of the most common faults faced in industrial plants / HVAC installations, is overheating [PFR-03 Phase Failure and Sequence Monitoring Relay]  and possible damage of three phase motors due to phase failure. The typical "thermo-magnetic relay", which is a common method of motor protection, is generally too slow to provide adequate protection due to electromechanical make-up and the usual use of high current settings to assure normal operation without false tripping.Phase Failure: When the monitored 3 phase supply voltage is valid, the PFR-03 output relay is ON. Should any of the 3 phases fail, the output relay switches OFF immediately.

Phase Sequence: When the phase sequence is correct (R, S, T in clockwise direction) The PFR-03 output relay is ON, should the phases not be in the above sequence, the output relay will be switched OFF immediately.

Voltage Imbalance: Should the voltage of each phase not be the same then the PFR-03 output relay will switch OFF within 0.2 seconds.