Siemens Actuator SQM40.235A20

The Siemens Actuator SQM40.235A20 is a rotary actuator designed for positioning air and gas dampers in burner systems. It operates on a 230 V supply and delivers a torque of 10 Nm. The actuator completes a 90° rotation in 30 seconds, making it suitable for continuous control applications in gas-fired equipment. This device is part of the Siemens SQM40 series and is intended for use in modulating combustion processes.

When selecting a replacement actuator of this type, verify the supply voltage, torque rating, runtime for the required rotation angle, and the rotation angle itself. Ensure the mounting dimensions and shaft coupling match the existing installation. Check the control signal compatibility (e.g., three-point or continuous) with the burner management system. Confirm the rotation direction and any auxiliary switch configurations before installation.

Common failures in actuators of this kind include stripped gears due to mechanical overload, failed end switches that no longer signal limit positions, and seized output shafts after prolonged inactivity. Symptoms may include the damper not moving to the commanded position, erratic positioning, or the actuator running continuously without stopping. Check for unusual noises, overheating, or visible damage to the gear train and wiring.