Siemens Burner Servomotor SQN30.251A2700

Product Details

The Siemens SQN30 series (and its counterpart, the SQN31) consists of small electromotoric actuators designed to drive gas or air dampers on small to medium-sized burners.1 They are highly reliable and are typically controlled by burner management systems like the LGB, LME, or LMO. 1. Model Differentiation The primary difference between the two main series is the direction of rotation: SQN30: Clockwise (CW) rotation (when looking at the shaft). SQN31: Counter-clockwise (CCW) rotation (when looking at the shaft). Model Running Time (for 90∘) Torque (Starting) Torque (Holding) SQN30.111 $4.5$ seconds $1.0$ Nm $0.8$ Nm SQN30.121 $4.5$ seconds $1.5$ Nm $0.8$ Nm SQN30.401 $30$ seconds $3.0$ Nm $1.2$ Nm SQN30.151 $12$ seconds $3.0$ Nm $1.2$ Nm 2. Technical Specifications Parameter Specification Mains Voltage 220V- 240 AC (or 110\text{V}$ variant) Frequency $50 - 60\text{ Hz}$ Power Consumption Approx. $6.5$ VA Duty Cycle $60\%$ (intermittent operation) Angular Adjustment Max 160^ Protection Class IP40 (when mounted correctly) Operating Temperature $-20\text{°C}$ to $+60\text{°C}$ Mounting Position Optional (Any orientation) Weight Approx. 0.5 kg 3. Internal Features & Components The SQN30 is a "Smart" mechanical actuator  containing a reversible synchronous motor and a specialized gear train. Adjustable Cams: It contains multiple cams (usually color-coded) that trigger microswitches to define: High-Fire (Max) Position: Usually a Red cam. Low-Fire (Min) Position: Usually a Blue cam. Ignition/Auxiliary Positions: Usually Orange or Black cams. Manual Disengagement: A small lever or push-button allows the gear train to be decoupled so the shaft can be turned by hand during commissioning. Shaft Options: Typically features a 10 mm diameter shaft with a flat side ("D-shape") or a square shaft depending on the specific burner assembly requirement. 4. Control Wiring The SQN30 series supports various control methods depending on the terminal configuration (versions A, B, or C): 2-Stage Control: Moves between a pre-set Minimum and Maximum position based on a single-pole switch . Modulating Control: When used with a PID controller (like the Siemens RWF series), the actuator can be stopped at any intermediate position to precisely match the heat demand. 5. Maintenance and Replacement   Lubrication: The gear train is permanently lubricated and does not require maintenance. Replacement Warning: When replacing an SQN30, ensure the running time  4.5s vs 30s) matches exactly. If the running time is too slow, the burner controller may time out and go into "Air Pressure Failure" or "Sequence Error."