Siemens Building Technology GMA121.1U Actuator

The Siemens GMA121.1U is a heavy-duty spring return damper actuator engineered for high-demand HVACR applications requiring reliable fail-safe operation. Operating on 24VAC/DC, this direct-coupled actuator delivers a robust 62 lb-in torque (7 Nm), making it an ideal choice for managing return air, mixed air, and exhaust dampers in both constant and variable air volume systems. Built with a rugged, die-cast aluminum NEMA 1 housing, this unit ensures longevity in commercial environments where performance is non-negotiable. The two-position (on/off) control logic is powered by a brushless DC motor with stall protection, preventing motor burnout during locked-rotor conditions. A 90-second run time provides precise air regulation, while the mechanical spring return executes a fail-safe closure in under 15 seconds upon power loss. For rapid field installation, the Siemens GMA121.1U features a unique self-centering shaft coupling and a 3-foot pre-wired appliance cable, reducing labor time for contractors and ensuring HVAC damper control accuracy.

• Fail-Safe Reliability: Mechanical spring return ensures the damper reaches a secure position during power interruptions.
• High Torque Performance: Delivers 62 lb-in of torque, sufficient for large-scale commercial HVAC dampers.
• Brushless DC Technology: Includes electronic stall protection to increase the service life of the motor.
• Simple Commissioning: Self-centering shaft coupling fits various shaft sizes and eliminates the need for complex mounting brackets.
• Manual Override: Integrated manual positioning allows for easy system testing and maintenance.

What is the fail-safe direction of the GMA121.1U?
The spring return direction is bi-directional; the orientation of the actuator on the damper shaft determines whether it fails open or fails closed.

Can this actuator be used with 120V power sources?
No, this specific model requires 24V AC/DC. Using a higher voltage will damage the internal electronics. For 120V applications, the GMA221.1U should be used.

Does this model include auxiliary switches?
The standard GMA121.1U does not include built-in auxiliary switches. If position feedback is required, an external switch kit or a model ending in '.1W' or '.1E' must be sourced.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.