HT 22 is preferably used for simple regulation tasks or as an additional monitor. The regulator is equipped with a PD feedback and has an adjustable regulation amplification for the adaptation to different controlled systems. It has an electronic reference junction for thermoelements. The relay is equipped with a potential-free change-over contact. As the number of switchings is limited, the abrasion of the relay contacts is reduced. In case of an interrupted sensor line or if the sensor element is deficient, the device will immediately cut off. A control lamp indicates the failure. The large connection space is provided with self-locking terminals. According to VDE, a main switch must be superposed to the regulator.