NFB24-SR-S Belimo Actuator

Datasheet

Installation Guide

Application

For fail-safe, modulating control of dampers in HVAC systems. Actuator sizing should be done in accordance with the damper manufacturer’s specifications. The actuator 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 applications where the actuator cannot be direct coupled to the damper shaft. The actuator operates in response to a 2 to 10 VDC or, with the addition of a 500Ω resistor, a 4 to 20 mA control input from an electronic controller or positioner. A 2 to 10 VDC feedback signal is provided for position indication. Not to be used for a master-slave application.

Operation

The NF..24-SR-S series actuators provide 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. The NF..24-SR-S series provides 95° of rotation and is provided with a graduated position indicator showing 0° to 95°. The NF..24-SR-S uses a brushless DC motor which is controlled by an Application Specific Integrated Circuit (ASIC) and a microprocessor. The microprocessor provides the intelligence to the ASIC 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. The NF..24-SR-S versions are provided with two built-in auxiliary switches. These SPDT switches provide safety interfacing or signaling, for example, for fan start-up. The switching function at the fail-safe position is fixed at 10°, the other switch function is adjustable between 10° to 90°. The NF..24- SR-S actuator is shipped at 5° (5° from full fail-safe) to provide automatic compression against damper gaskets for tight shut-off.

Specifications

• Actuator Type
  • Spring return
• Angle of Rotation
  • 95°
• Auxiliary Switches
  • 2 x SPDT
• Control Type
  • Modulating
• Degree of Protection
  • IP54, NEMA 2, UL Enclosure Type 2
• Direction of Rotation (Fail-Safe)
  • Reversible with cw/ccw mounting
• Electrical Connection
  • Cable
• Manual Override
  • 5 mm hex crank (3/16″ Allen), supplied
• Power Consumption (Holding)
  • 5 W
• Power Consumption (Running)
  • 5 W
• Running Time (Fail-safe)
  • <20 s
• Running Time (Motor)
  • 95 s
• Safety Function
  • YES
• Shaft Diameter
  • 1/2…1.05″ round, centers on 1/2″ and 3/4″ with insert, 1.05″ without insert
• Torque
  • 90 in-lb [10 Nm]
• Voltage AC/DC
  • AC/DC 24 V