Siemens Burner Servomotor SQN70.424A20

Product Details

The Siemens SQN70 (and its counterpart SQN71) is a range of electromotoric actuators designed to drive gas or air dampers on small to medium-sized burners.1 They are often referred to as "high-torque" compact actuators compared to the SQN30 series and are typically used with burner controllers like the LME, LMO, or LGB.   1. SQN70 vs. SQN71: Direction of Rotation SQN70: Rotates Clockwise (CW) when looking at the drive shaft. SQN71: Rotates Counter-clockwise (CCW) when looking at the drive shaft. 2. All Models & Running Times The model number determines the internal circuit (Version A, B, C, or D), the running time, and the torque. Model Series Running Time (90∘ at 50Hz) Starting Torque Holding Torque SQN7x.2 $4$ seconds $1.5$ Nm $0.5$ Nm SQN7x.4 $12$ seconds $2.5$ Nm $1.3$ Nm SQN7x.6 $30$ seconds $2.5$ Nm $1.3$ Nm Versions/Circuits Version A: For 2-stage control (High/Low) with no internal electronic ratio control. Version B: Primarily for use with controllers like the LME22. Version C: Designed for modulating control via a 3-position signal (Open/Stop/Close). Version D: Typically used with the LFL series or for specific industrial sequences. 3. Technical Specifications Feature Specification Mains Voltage $220\dots240\text{V AC}$ (Suffix A2) or $100\dots110\text{V AC}$ (Suffix A1) Frequency $50 - 60\text{ Hz}$ Power Consumption $6$ VA Angle of Rotation Max $160^\circ$ (Adjustable) Protection Class IP40 Operating Temp $-20\text{°C}$ to $+60\text{°C}$ Drive Shaft $10$ mm square or "D" shaft options 4. Internal Components The SQN70 series features a reversible synchronous motor and a gear train that can be manually disengaged for adjustment.2   The Cam Logic Inside the housing are several color-coded cams that trigger microswitches to define the operational limits: Red Cam: Maximum position (High-fire). Blue Cam: Minimum position (Closed or Low-fire). Orange/Black Cams: Auxiliary switches for "Ignition load" or "Release of fuel." 5. Key Features Maintenance-Free: The gear train is permanently lubricated. Manual Release: A push-button or lever on the housing allows the gears to be decoupled. This is vital for checking the mechanical linkage for binding without the motor running. Potentiometer Option: Some SQN70 models can be retrofitted with a $1,000\ \Omega$ potentiometer for position feedback to a PLC or display unit. 6. Maintenance and Selection Tip Direction: (70 vs 71). Running Time: (e.g., $2$s vs $30$s). If you install a slower actuator, the burner controller might go into lockout during the pre-purge transition.