Siemens Actuator Servomotor SQN7 Series

Siemens Actuator Servomotor SQN7 Series – Burner Air and Gas Damper Control

Siemens Actuator Servomotor SQN7 Series is an electromotoric actuator designed to drive and control the position of air dampers, gas dampers, and associated control devices in small- to medium-capacity oil and gas burner systems. It supports the adjustment of combustion air and fuel delivery according to the operating load of the burner.

The actuator uses a synchronous motor combined with a reduction gear train and cam switch mechanism to establish and control rotational positions. It provides a nominal torque of 1.5–2.5 Nm, a holding torque of 0.7–1.3 Nm, and a 90° running time of approximately 4–30 seconds, depending on the model. The SQN7 family consists of SQN70, SQN71, SQN74, and SQN75 series, with differences in rotation direction and mounting configuration.

Key Features of Siemens SQN7 Series

• Synchronous motor for positioning air and gas dampers.

• Nominal torque of 1.5–2.5 Nm and holding torque of 0.7–1.3 Nm.

• Approximately 4–30 seconds running time for 90° rotation at 50 Hz, depending on the model.

• Adjustable cam switches for setting end switch and auxiliary switch positions.

• Internal position indicator for monitoring actuator position.

• Maintenance-free reduction gear train with a disengagement mechanism for position adjustment.

• Impact-resistant and heat-resistant plastic housing.

• Supports 2-stage and modulating operation, depending on the actuator version and control circuit.

Technical Specifications

• Model: Siemens SQN70 / SQN71 / SQN74 / SQN75 Series

• Motor Type: Synchronous Motor

• Nominal Torque: 1.5–2.5 Nm

• Holding Torque: 0.7–1.3 Nm

• Running Time (90°): 4–30 seconds at 50 Hz, depending on model

• Supply Voltage: AC 230 V / AC 115 V, depending on model

• Frequency: 50–60 Hz

• Power Consumption: Maximum 6 VA

• Usable Positioning Angle: Maximum 160°

• Rotation Direction: SQN70 / SQN74 counterclockwise; SQN71 / SQN75 clockwise

• End Switches: 2

• Auxiliary Switches: Number varies by model

• Protection Rating: IP40 under specified installation conditions; IP20 for SQN74 / SQN75 when the lateral cable entry opening is used

• Operating Temperature: -20°C to +60°C

• Weight: Approximately 500 g

• Designed Lifetime: 250,000 burner startup cycles under manufacturer-specified operating conditions

Siemens SQN7 Series Models

• SQN70 Series: Counterclockwise rotation, approximately 4–30 seconds for 90° movement.

• SQN71 Series: Clockwise rotation, approximately 4–30 seconds for 90° movement.

• SQN74 Series: Counterclockwise rotation, approximately 4 seconds for 90° movement.

• SQN75 Series: Clockwise rotation, approximately 4–30 seconds for 90° movement.

Applications of Siemens SQN7 Actuator

Siemens SQN7 Series is suitable for controlling air and gas dampers in industrial boilers, industrial furnaces, hot water generators, and heating systems equipped with oil or gas burners.

Depending on the model and wiring configuration, it can operate with Siemens burner controls such as LAL, LFL, LME, LGB, LOA, LMO, LGK16, and LOK16, as well as RWF50 / RWF55 controllers. These configurations allow damper positioning in accordance with burner operating load.

Selection Recommendations

Before purchasing or replacing an actuator, verify the complete existing model number, torque requirements, rotation direction, running time, supply voltage, shaft dimensions, and control circuit. These checks help ensure that the Siemens SQN7 Actuator can be properly installed and operated with the existing burner system.

Siemens SQN7 Series is an electromotoric actuator for positioning air and gas dampers in burner systems. It features a synchronous motor, a maintenance-free gear train, and adjustable cam-operated end and auxiliary switches. With a nominal torque of 1.5–2.5 Nm and a 90° running time of approximately 4–30 seconds, the series includes SQN70, SQN71, SQN74, and SQN75 models to accommodate different rotation directions, supply voltages, and control requirements.