The Belimo NF24-SR US spring return actuator is designed for proportional modulation of dampers in HVAC systems. Actuator sizing should be done in accordance with the damper manufacturer’s specifications.

The NF24-SR US is mounted directly to a damper shaft up to 1.05” in diameter by means of its universal clamp. A crank arm and several mounting brackets are available for additional applications. The NF24-SR US operates in response to a 2-10 VDC, or with the addition of a 500 resistor, a 4-20 mA control input from an electronic controller or positioner. A feedback signal is provided for position indication or master-slave applications.

Features

The NF24SR US also provides true spring return operation for reliable fail-safe application and positive close-off on air tight dampers. The spring return system provides constant torque to the damper with, and without, power applied to the actuator. Ninety-five degrees of rotation with a graduated position indicator showing 0° to 95°.

A brushless DC motor is controlled by an ASIC and a microprocessor, which provides intelligence to the ASIC in order to provide a constant rotation rate and to know the actuator’s exact fail-safe position. The ASIC monitors and controls the brushless DC motor’s rotation and provides a digital rotation sensing function to prevent damage to the actuator in a stall condition. The actuator may be stalled anywhere in its normal rotation without the need of mechanical end switches.

Product Specifications