Sensor Retrofitting of Motors For Protection Against Overtemperature

Low-cost fast-response thermal sensors are making it possible to add overtemperature protection to industrial motors on a retrofit basis. Easily applied by regular maintenance personnel, this protection system offers industrial plants, large and small, the opportunity for longer, trouble-free motor life, The application of sensors to existing induction motors to prevent thermal damage resulting from abnormal running overload or locked rotor conditions is also described here. Basic considerations for proper application are discussed, including motor winding configurations, insulation classes, and other design characteristics. Motor rewind shops provide a basic area of application where the sensors can be integrally installed in the stator winding at the time of repair. Examples and experiences are discussed where applications have been made.