Belimo LF24-3 US - User Manual

J20741 - Subject to change. © Belimo Aircontrols (USA), Inc.
LF24-3 (-S) US
On-off, Spring Return Fail-Safe, Reversible, Floating Point, 24V
Torque min. 35 in-lb, for control of air dampers
Application
For modulation or on-off 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 from 3/8”
up to 1/2” in diameter by means of its universal clamp, 1/2”
shaft centered at delivery. For shafts up to 3/4” use K6-1
accessory. A crank arm and several mounting brackets are
available for applications where the actuator cannot be direct
coupled to the damper shaft.
Control is floating point from a triac or relay, or on-off from an
auxiliary contact from a fan motor contactor, controller, or
manual switch.
Operation
The LF 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 consistent torque
to the damper with, and without, power applied to the actuator.
The LF series provides 95° of rotation and is provided with a
graduated position indicator showing 0 to 95°.
The LF24-3 (-S) US uses a brushless DC motor which is con-
trolled by an Application Specific Integrated Circuit (ASIC) and a
microprocessor. The microprocessor provides the intelligence to
the ASIC to provide a constant rotation rate. The ASIC monitors
and controls the brushless DC motor’s rotation and provides a
digital rotation sensing function to prevent damage to the actua-
tor in a stall condition. The actuator may be stalled anywhere in
its normal rotation without the need of mechanical end switches.
Power consumption is reduced in holding mode.
The LF24-3-S US version is provided with 1 built-in auxiliary
switch. This SPDT switch is provided for safety interfacing or
signaling, for example, for fan start-up. The switching function
is adjustable between 0° and 95°. The auxiliary switch in the
LF24-3-S US is double insulated so an electrical ground is not
necessary.
Dimensions
[All numbers in brackets are in millimeters.]
Technical Data LF24-3 (-S) US
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 LF24-3 US 3 ft, plenum rated cable
LF24-3-S US 3 ft, 18 GA appliance
cables (2)
1/2” conduit connector
Overload protection electronic throughout 0 to 95° rotation
Input impedance 1000 Ω (0.6w) control inputs
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)
Auxiliary switch 1 x SPDT 3A (0.5A) @ 250 VAC,
UL listed
(LF24-3-S US) adjustable 0° to 95° (double insulated)
Running time 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 metal
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 LF24-3 3.1 lbs (1.40 kg)
LF24-3-S 3.6 lbs (1.45 kg)
LISTED
94D5
TEMP. IND &
REG. EQUIP.
U
L

®
70
0.39" [10]
7.67" [195]
3.66" [93]
1.93"
[49]
6.10" [155]
3.15" [80]
3.86"
[98]
0.256" [6.5]
0.98"
[25]
4.92" [125]
0.79"
[20]
0.5"
[12.7]
0.71" [18]
0.74" [18.7]
2.24"
[57]
3.23" [82]
0.25" [6.3]
Standard:
3/8" to 1/2"
3/8" to 7/16"
Optional
1/2" to 3/4"
w/K6-1
accessory
D010

Belimo LF24-3 US Specifications