Model 5CX-371 full proportional temperature controller features full isolation between and AC input power to the controller and the output stage. Transformer isolation between the AC input and control circuit permits operation of the control circuit from a low DC potential. This means that only low potential exists on the sensor connections and external potentiometer, when used.
The primary of the input transformer is designed for 120 VAC operation. Isolation of the output stage is achieved by using an optically coupled semiconductor device to drive the output triac. This optically coupled device provides electrical isolation between the control circuit and the output stage.