The DHC motor protection relay is a temperature monitoring relay for electro motors. It evaluates the resistance values of the PTC resistor integrated in the motor coil. A zero-voltage safe electronic restart interlock ensures that the relay will remain locked upon activation even in the event of power failure, i.e. an uncontrolled restart will be avoided.

The advantages are a high degree of safety because of the restart interlock and closed circuit principle. Multiple sensor resistances can be connected to a relay. When the normal temperature is reached, the motor is started via a built-in acknowledgement button.