The Phase Balance/Sequence Relay is sensitive to phase unbalance, phase reversal, and phase loss in three-phase power systems. It can be used to initiate an action should any one of the hazards mentioned above occur. For instance, the sensitivity to phase unbalance allows protection of a three-phase induction motor against excessive temperature rise due to unbalanced supply voltages. Unbalance setpoint and time delay adjustments as well as two sets of contacts are provided. The adjustable time delay is a useful feature which can prevent premature relay operation on short duration supply fluctuations.