The actuators with safety function are mainly used with VZ valves (AMV 13 SU) or with VS, VM or VB valves (AMV 13 SU, AMV 23 SU) or AVQM (AMV 23 SU). Safety version is activated automatically in case of power failure or if the power supply is switched off by the safety thermostat. The actuator automatically adapts its stroke to valve end positions which reduces commissioning time. Optional feedback potentiometer is available on special request.