Siemens Actuator SQN30.111A2700

This actuator is a replacement part for positioning air dampers or mixing valves in burner and boiler systems. It is designed for a supply voltage of 220–240 V AC at 50–60 Hz and provides a torque of 1 Nm. Its running time is 4.5 seconds, and it is equipped with two auxiliary switches. The housing length is 110 mm, and the rotation direction is counterclockwise.

Actuators of this type are selected according to required torque, running time, control signal format (three-point, 0-10 V DC, or on/off), the shaft or coupling pattern, the angle of rotation, and the presence of auxiliary limit switches. When replacing, check that the mechanical interface (shaft diameter, keyway, or square drive) is compatible with the damper or valve, and that the electrical ratings of the control signal and auxiliary contacts match the existing circuit.

Common failure modes for this type of actuator include stripped gear trains, worn or burnt auxiliary switches, and a seized valve stem after prolonged standstill. These faults are more likely after a summer shutdown. When they occur, the actuator may fail to position the damper or valve, or the auxiliary switches may not operate correctly. Check the actuator's response to the control signal and inspect the gear train and switches for wear.