The Belimo LF24-SR US LF Damper Actuator is designed for proportional control of dampers in HVAC systems. Actuator sizing should be done in accordance with the damper manufacturer’s specifications. The LF24-SR US is mounted directly to a damper shaft, measuring between 3/8” up to 1/2” in diameter, with a universal clamp. For shafts up to 3/4” use K6-1 accessory. A crank arm and several mounting brackets are available for other applications.
The LF24-SR US actuator provides true spring return operation for reliable fail-safe application and positive close off on air tight dampers. The spring return system provides consistent torque to the damper with, and without, power applied to the actuator. Also provides 95° of rotation and is provided with a graduated position indicator showing 0° to 95°.
The LF24-SR US also includes a brushless DC motor controlled by ASIC and microprocessor, providing a constant rotation rate. The ASIC monitors and controls the DC motor's rotation and provides a digital ratation sensing function to prevent actuator damage when stalled. No mechanical end switches are needed in order to stall the actuator anywhere in it normal rotation. Holding mode reduces power consumption.
Product Specifications
| Power supply |
24 VAC ± 20% 50/60 Hz, 24
VDC ± 10% |
| Power
consumption |
running: 2.5 W; holding: 1
W |
| Transformer
sizing |
5 VA (class 2 power
source) |
| Electrical
connection |
3 ft, plenum-rated cable
and 1/2”
conduit connector |
| Overload
protection |
electronic throughout 0°
to 95°
rotation |
| Operating range
Y |
2 to 10 VDC, 4 to
20mA |
| Input
impedance |
100kΩ
(0.1 mA), 500Ω |
| Feedback output
U |
2 to 10 VDC (max 0.7 mA)
for 95° |
| Angle of
rotation |
max 95°, adjust with
mechanical stop |
| Torque |
35 in-lb [4 Nm] |
| Direction of
rotation |
spring: reversible with
CW/CCW
mounting
motor: reversible with built-in switch |
| Position
indication |
visual indicator, 0° to
95° (0° is
spring return position) |
| Running time
(nominal) |
Motor: 150 sec. constant,
independent
of load,
spring: < 25 sec @-4°F to +122°F [-20°C to +50°C]
< 60
sec @-22°F
[-30°C] |
| Humidity |
5 to 95% RH
non-condensing |
| Ambient
temperature |
-22°F to +122°F [-30°C to
+50°C] |
| Storage
temperature |
-40°F to +176°F [-40°C to
+80°C] |
| Housing |
NEMA type 2 /
IP54 |
| Housing
material |
zinc coated steel |
| Agency
listings |
UL 873 listed, CSA C22.2
No. 24
certified, CE |
| Noise level |
max. running < 30
db (A)
spring return 62 dB (A) |
| Servicing |
maintenance free |
| Quality
standard |
ISO 9001 |
| Weight |
3.1 lbs (1.4 kg) |