3 phase supply control relay 

(Phase sequence relay) is designed to monitor 3 phase supplies and to protect motors and other loads against the faults listed below.

· Monitoring of rotational direction of phases

· Detection of complete failure of one or more of the phases

· Undervoltage detection (-10%)

· Overvoltage detection (+10%)

· Detection of phase asymmetry (imbalance) (±10%)

The relay operates if any of the conditions occours.

The relay releases if any of the conditions fails.

There is a Time Delay between the relay action and the condition occours (except rotational direction of phases error ) to avoid very short interruptions or other momentary failures.

A selector switch allows selection of an adjustable time delay from 0.1s to 10s.

When the supply returns towards its rated value, the relay is re-energised according to the hysteresis value (5%).

 Picture