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General

The Belimo LF24-SR is a fail-safe rotary actuator designed for controlling air dampers in heating, ventilation and air conditioning (HVAC) systems. It provides a torque of 4 Nm and operates on a 24 V AC/DC power supply, making it suitable for modulating damper control in commercial and industrial building installations.

The actuator uses a 2–10 V modulating control signal to position the damper and provides a 2–10 V feedback signal to communicate its actual position to the building management or control system. Its spring-return fail-safe mechanism automatically drives the damper to its configured safety position when the power supply is interrupted.

With a maximum rotation angle of 95°, selectable direction of rotation and a universal shaft clamp, the LF24-SR offers flexible installation. It is designed for air dampers with a size of approximately 0.8 m², depending on the damper design and operating conditions.

Features

- Fail-safe rotary actuator for HVAC air dampers
- 4 Nm motor torque and fail-safe torque
- 24 V AC/DC power supply
- Modulating control signal: 2–10 V DC
- Position feedback signal: 2–10 V DC
- Spring-return fail-safe operation
- Motor running time: 150 seconds per 90°
- Adjustable motor running time: 75–300 seconds
- Fail-safe running time: Less than 20 seconds under specified conditions
- Maximum rotation angle: 95°
- Selectable motor direction of rotation
- Universal shaft clamp for 8–16 mm shafts
- IP54 protection rating
- Low-noise operation
- Maintenance-free design

Key Specifications

- Make: Belimo
- Model: LF24-SR
- Part Number: LF24-SR
- Product Type: Fail-Safe Rotary Damper Actuator
- Application: HVAC Air Damper Control
- Motor Torque: 4 Nm
- Fail-Safe Torque: 4 Nm
- Nominal Voltage: 24 V AC/DC
- Voltage Frequency: 50/60 Hz
- Control Signal: 2–10 V DC
- Position Feedback: 2–10 V DC
- Input Impedance: 100 kΩ
- Power Consumption (Running): 2 W
- Power Consumption (Holding): 0.8 W
- Power for Wire Sizing: 3.5 VA
- Motor Running Time: 150 s / 90°
- Adjustable Running Time: 75–300 s
- Fail-Safe Running Time: Less than 20 s
- Maximum Rotation Angle: 95°
- Shaft Connection: Universal shaft clamp, 8–16 mm
- Protection Rating: IP54
- Protection Class: III (SELV)
- Ambient Temperature: -30°C to +50°C
- Maximum Damper Size: Approximately 0.8 m²
- Manual Override: Not available

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