Thermistor Motor Protection Relay monitors motor winding temperature in real-time using PTC/NTC thermistors, triggering protection (alarm or power cutoff) against overheating. Horsepower and kilowatts the standard unit of measure for electric motors. Ratings of AC and DC motors can range from as little as a micro. Electric motors are the indispensable feature and core of commercial and industrial operations. From driving pumps, compressors, fans, and conveyors, to offering day-to-day operations, they ensure machines operate in good condition. However, like any other machine, they too are prone to failures. Motor Protective Relay applications can be grouped by purpose into the following categories.