ICM UMSR50 Universal Motor Starting Relay 50A A wire-for-wire replacement for all standard potential relays that operate a single-phase motor with a voltage range of 110-502 VAC. The new relay is ideal for applications such as A/C, commercial refrigeration, heat pumps or any single-phase motor application up to 10 HP. Unique to the UMSR is its patented differential voltage sensing technology that ensures the exact starting voltage for each motor, every time; there are no user adjustments to make at set-up, making installation easier and more accurate. Additionally, a single UMSR unit can be used in place of hundreds of competitive models, translating into a dramatic cost-savings through inventory reduction.