Siemens SQM54.481A203 Servomotor Actuator

Overview
The Siemens SQM54.481A203 is a high-performance rotary actuator designed for controlling dampers, valves or other flow regulators in HVAC, burner and industrial combustion systems. It features a 90° rotary travel, 25 Nm torque, 8 integrated auxiliary switches, and a 10 mm + key shaft configuration. The unit is engineered for reliable service and precise positioning in demanding applications, meeting CE standards and suitable for AC 240 V operation.

Key Features

• 25 Nm nominal torque

• 90° rotation angle in approx. 30 seconds

• 8 auxiliary switches for advanced control and feedback

• Shaft diameter 10 mm with keyway for secure coupling

• AC 240 V version (specified for this particular model)

• CE-compliant design, suitable for use with burner, valve or damper applications

• Compact, rugged construction suitable for industrial or HVAC installation

• Suitable for modulating control, positioning dampers/valves in combustion or air/gas flows

Main Benefits

• Precise positioning of valves or dampers ensures accurate control of flow or combustion air

• Robust construction supports long service life in HVAC or burner environments

• Built-in auxiliary switches simplify integration into control systems (e.g., limit switches, signal feedback)

• Compact form factor allows for easier mounting in confined spaces

• Standard shaft and keyway facilitate direct mechanical connection and retrofit into existing installations

• Siemens reputation means high quality and availability of service documentation

Technical Highlights

• Nominal torque: 25 Nm

• Rotation angle: 90° (in approx. 30 seconds)

• Auxiliary switches: 8 mechanical switches for status/limit control

• Shaft: 10 mm diameter + keyway (model specific)

• Supply voltage: AC 240 V (specific to this model variant)

• Application: Positioning of dampers, valves or linkages in HVAC, burner control, air/gas flow regulation

Installation & Safety Notes

• Installation should be carried out by qualified personnel in accordance with local installation, wiring and safety regulations.

• Ensure the actuator shaft coupling aligns properly with the valve/damper drive shaft and keyway.

• Disconnect mains power before wiring or service.

• Check mechanical travel stops, auxiliary switch settings and control wiring prior to commissioning.

• Refer to Siemens datasheet for mounting orientation, torque limits, and service intervals.

Applications

• Burner damper control in oil/gas fired equipment

• Air or gas flow dampers in HVAC systems

• Valve actuation in process or industrial systems

• Retrofit of existing actuator installations requiring 25 Nm torque and 90° travel