Siemens Burner Servomotor SQN90.240b2793

Product Details

Energy Combustion, Ahmedabad importer and suppliers of Siemens make burner servomotor and other accessories for industrial applications.The Siemens SQN90 is a series of compact, reversible electromotoric actuators used for the control of air and gas dampers on small to medium-sized burners. They are often used in conjunction with burner controllers like the LMO, LME, or LGB. 1. Primary SQN90 Models The specific model suffix determines the direction of rotation, torque, and running time. Model Rotation (viewed from shaft) Running Time (90°) Torque SQN90.204A27 Clockwise (CW) $12\text{ seconds}$ $2.4\text{ Nm}$ SQN91.204A27 Counter-clockwise (CCW) $12\text{ seconds}$ $2.4\text{ Nm}$ SQN90.564A27 Clockwise (CW) $24\text{ seconds}$ $3.0\text{ Nm}$ SQN90.240B27 Clockwise (CW) $4\text{ seconds}$ $0.8\text{ Nm}$ 2. Technical Specifications Mains Voltage: $230\text{V AC}$ ($+10\% / -15\%$) or $115\text{V AC}$ variants. Frequency: $50\dots 60\text{ Hz}$. Power Consumption: Approx. $8\text{ VA}$. Angular Adjustment: Max $160\text{°}$ (standard factory set to $90\text{°}$). Protection Class: IP40 (when mounted correctly). Operating Temp: $-20\text{°C}$ to $+60\text{°C}$. Mounting Position: Optional (can be mounted horizontally or vertically). Shaft Type: $8\text{ mm}$ square shaft or "D" shaped shaft (depending on the version). 3. Internal Components & Adjustments The SQN90 contains a set of adjustable cams that control the travel limits and auxiliary switches: End Switches: Two switches (red and blue cams) define the Maximum Open and Minimum/Closed positions. Auxiliary Switches: Up to three additional switches (black or grey cams) can be used to signal the burner controller when the damper has reached a specific intermediate position (e.g., "Ignition Position"). Manual Release: Most models feature a push-button or lever to disengage the gears, allowing the shaft to be turned by hand for setup and commissioning. 4. Key Features Reversible Motor: Unlike some older actuators, the SQN90 can move in both directions, allowing for precise modulating control when paired with a PID controller. Internal Potentiometer (Optional): Some versions can be fitted with a $1000\ \Omega$ or $5000\ \Omega$ potentiometer to provide feedback on the actual position to a remote display or PLC. 5. Wiring Overview The actuator typically connects via a plug-in screw terminal block. Terminals 1 & 2: Usually the "Open" and "Close" control signals from the burner controller. Auxiliary Terminals: Used to "prove" to the burner controller that the air damper is fully open during the pre-purge phase. Note: When replacing an SQN90, always check the direction of rotation (SQN90 = Clockwise, SQN91 = Counter-clockwise) as installing the wrong one can cause the burner to fail its pre-ignition safety checks.