Time Mark 253 Reverse Phase Relay 3 Phase Power Consists of a microcontroller Fault condition will de-energize the relay Does not require a neutral connection Detect phase loss on a loaded motor The Model 253 Reverse Phase Relay is a solid-state sensing device designed for installation in equipment using 3-phase power. This unit is used where it is desirable to have a contact closure indicating that the proper phase rotation sequence has been applied. The relay closes when the proper sequence (A B C) is applied, but will remain open if any two phases are reversed. If reverse phasing occurs during operation, the relay also de-energizes. The Model 253 has a special industrial grade relay designed for low power consumption. The A B C indicator will be illuminated when the proper phase rotation sequence is applied.