The Siemens SQN72.4D5B20BT is an electromechanical damper actuator (servomotor) from the SQN72 series, designed for air damper and fuel valve control in industrial oil and gas burner systems. It provides 2.5 Nm nominal torque with 12-second running time for 90° rotation, counterclockwise direction, and 1.2 Nm holding torque. The synchronous motor operates at ~6 VA with up to 160° angular positioning. The SQN72 series is widely used with Siemens LMV burner management systems for precise combustion air/fuel ratio control. Typical applications include industrial boilers, process heaters, thermal oil heaters, and any application requiring reliable modulating damper or valve actuation in combustion systems.
**Q: What is the difference between SQN70, SQN71, and SQN72 series?**
A: SQN70 and SQN72 rotate counterclockwise; SQN71 rotates clockwise. SQN72 has additional features compared to SQN70.
**Q: Can the running time be adjusted?**
A: The running time is fixed by the model variant. The ".4" in the part number indicates 12s running time. Other variants offer 4s (.2) or 30s (.6).
**Q: Is this actuator compatible with non-Siemens burner controls?**
A: It is designed for Siemens LMV systems but may interface with other controllers using standard 0-10V or 4-20mA positioning signals depending on the specific variant configuration.
