This protector is designed to protect 3-phase refrigeration and air conditioning compressor motors from excessive winding temperature; however, applications may be made to any WYE wound 3-phase motors where environmental conditions require a hermetic seal. The low profile permits the device to be installed directly on motor windings for closely coupled temperature monitoring, thus enhancing over-temperature protection against loss of refrigeration charge, low voltage locked rotor, and single-phasing (loss of phase). The 37HM is designed to reduce installation costs by replacing pilot control systems with a simple, economical, compact device.