Description
The Belimo LF24-SR-S US is a compact spring return damper actuator providing 35 in-lb (4 Nm) of torque for precise modulating airflow control. It operates on AC/DC 24 V power and supports 2–10 V control with integrated auxiliary switching and position feedback.
Technical Specifications
| Condition |
New/Never Used Surplus |
| Brand |
Belimo |
| Category |
Dampers & Actuators |
| Part Number |
LF24-SR-S US |
| Subcategory |
Damper Actuators |
| Nominal Voltage |
AC/DC 24 V |
| Nominal Frequency |
50/60 Hz |
| Voltage Range |
AC 19.2…28.8 V / DC 21.6…28.8 V |
| Power Consumption (Operation) |
2.5 W |
| Power Consumption (Rest) |
1 W |
| Transformer Sizing |
5 VA |
| Control Signal |
2…10 V (4…20 mA with resistor) |
| Input Impedance |
100 kΩ (2…10 V), 500 Ω (4…20 mA) |
| Position Feedback |
2…10 V |
| Torque Output |
35 in-lb (4 Nm) |
| Angle of Rotation |
Max. 95° |
| Running Time (Motor) |
150 s / 90° |
| Running Time (Fail-Safe) |
<25 s |
| Auxiliary Switch |
1x SPDT, adjustable |
| Electrical Connection |
18 AWG cables, 1 m, 1/2" NPT |
| Degree of Protection |
NEMA 2 |
| Ambient Temperature |
-30…50°C |
| Noise Level |
30 dB(A) motor |
| Weight |
3.3 lb (1.5 kg) |
Information About LF24-SR-S US
The LF24-SR-S US is part of Belimo’s LF series of low-torque spring return actuators engineered for accurate control of small air dampers in HVAC systems. It features a double-insulated design with electronic overload protection throughout the full rotation range to maintain consistent performance and actuator longevity. The actuator supports modulating control via a 2…10 V signal and can be configured for 4…20 mA operation using an external resistor, ensuring compatibility with modern control platforms. Reversible fail-safe direction, selectable motor rotation, and an adjustable auxiliary switch provide installation flexibility and dependable system integration.
Key Features
- Spring Return Fail-Safe Operation: Integrated spring mechanism automatically drives the damper to a defined safety position during power loss, supporting airflow safety and system protection.
- Low Torque Precision Control: Delivers a constant 35 in-lb (4 Nm) torque output for accurate positioning of small and lightweight dampers.
- Modulating Control Interface: Accepts a 2…10 V control signal with optional 4…20 mA capability, allowing precise proportional airflow regulation.
- Integrated Auxiliary Switch: Includes one adjustable SPDT switch for position indication, interlocking, or control sequencing tasks.
- Electronic Overload Protection: Protects internal components across the full 0…95° rotation range by preventing damage from mechanical obstruction.
- Reversible Operation Configuration: Motor direction is selectable via onboard switch, while fail-safe direction can be changed through CW or CCW mounting.
- Quiet and Efficient Design: Engineered for low noise motor operation and minimal power consumption in continuously controlled HVAC environments.
The LF24-SR-S US delivers the reliability and precision required for modulating airflow control and dependable fail-safe damper positioning in HVAC applications.
