SDF series of damper actuator is a kind of universal type and direct-coupled quarter turn electric actuators,specialized designed for the dampers inside the HVAC system .It can make direct installation to the circular shaft, square shaft or abnormal shaft ,common adjustment 90°,maximum to 96°,also with tight structure , angle of rotation use 3° as a increment , torque includes : 5 Nm、10 Nm、20 Nm、40 Nm,adapt to dampers with different areas.Under the controlling of electri signal from the control system (Open-close, 3-point, DC0(2)～10Vor 4～20mA),output the torque of 5～40Nm, it can make the controlled objects rotate 0～90°, and output feedback signal of the corresponding position according to the requirements ,which display the angle of rotation or directly control the working of another actuators, Nominal voltage AC/DC24V and AC100...240V optional .adapt to air damper controlling with CAV or VAV.