The ABB Uninterruptible Power Supply (UPS) provides a dependable backup power to the protective relay(s) in the event the primary power source is lost. The UPS was specifically designed for use with the ABB Distribution Unit (DPU) and the ABB Integrated Microprocessor Protective Relay System (IMPRS) relays. It converts the voltage to DC control voltage and continues to provide that voltage for a period of time after the AC is lost.