Siemens Compact servo drive SQN72.2A4B20

This compact electromechanical actuator (servomotor) from Siemens is designed for precise air damper control in small and medium power burners, and is specifically compatible with Baltur burners. It operates on a 220–230 V AC supply and has a protection rating of IP54. The actuator delivers a 90° opening time of 4 seconds and consumes 6 W. It features a plug-in electrical connection and pre-drilled mounting holes for straightforward installation. No maintenance or lubrication is required.

Actuators of this type are selected by matching torque, running time, control signal type (three-point, 0-10 V, or on/off), shaft or coupling pattern, angle of rotation, and the presence and configuration of integral auxiliary switches. Before ordering, measure the shaft diameter and length, as well as the mounting hole spacing, and verify the electrical connection configuration. During installation, ensure the power supply and control signal match the actuator's rating, and that the mechanical coupling aligns freely without binding.

Typical failures in actuators of this class include stripped gear trains, faulty end switches, and seizure of the valve stem after extended idle periods. Symptoms may include the damper not moving, moving erratically, or the actuator humming without rotation. Check for mechanical obstructions, manually test the actuator rotation after disengaging the gear, and verify the end switches for continuity.