Belimo LF24 US - User Manual

Technical Data
1395
Power Supply 24 VAC ± 20%, 50/60 Hz, 24 VDC ± 10%
Power Consumption Running 5 W
Power Consumption Holding 2.5 W
Transformer Sizing 7 VA (class 2 power source)
Shaft Diameter 3/8” to 1/2” round, centers on 1/2”
Electrical Connection 3ft [1m], 18 GA appliance cable with 1/2”
conduit connector
Overload Protection electronic throughout 0° to 95° rotation
Electrical Protection actuators are double insulated
Angle of Rotation Max. 95°,
Torque 35 in-lbs [4 Nm] minimum
Direction of Rotation (Motor) reversible with CW/CCW mounting
Direction of Rotation (Fail-Safe) reversible with CW/CCW mounting
Position Indication visual indicator, 0° to 95° (0° is full spring
return position)
Running Time (Motor) <40 to 75 sec
Running Time (Fail-Safe) <25 sec @ -4°F to 122°F [-20°C to 50°C], <
60 sec @ -22°F [-30°C]
Humidity max. 95% RH non-condensing
Ambient Temperature Range -22°F to 122°F [-30°C to 50°C]
Storage Temperature Range -40°F to 176°F [-40°C to 80°C]
Housing NEMA 2, IP54
Housing Material zinc coated steel
Agency Listings† cULus acc. To UL 873 and CAN/CSA C22.2
No. 24-93
Noise Level (Motor) <50 dB (A)
Noise Level (Fail-Safe) <62 dB (A)
Servicing maintenance free
Quality Standard ISO 9001
Weight 3.1 lb [1.4 kg]
†Rated Impulse Voltage 800V, Type of action 1.AA, Control Pollution Degree 3
Torque min. 35 in-lb, for control of air dampers.
Application
For On/Off, fail-safe control of dampers in HVAC systems. Actuator sizing
should be done in accordance with the damper manufacturer’s specifications.
Control is On/Off from an auxiliary contact or a manual switch. 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.
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 actuator may be stalled
anywhere in its normal rotation without the need of mechanical end switches.
Power consumption is reduced in holding mode. The actuator is double
insulated so an electrical ground connection is not necessary.
Dimensions (Inches[mm])
2.74" [
69.6]
2.25" [
57.1]
0.73"
[
18.54]
3.23" [
82]
0.25"
[
6.25]
1.15"
[
29.3]
2.3" [
58.42]
3.15" [
80]
7.66 " [ 194.501]
0.2" [
5.08]
0.98 " [ 25] 4.72 " [ 120] 0.39 " [ 10]
0.97" [
24.6]
3.86" [
98]
1.69 " [ 43] 3.66 " [ 93]
6.1 " [ 155]
3.66 " [ 93]
6.1 " [ 155]
0.26 " [ 6.5]
LF24 US - Damper Actuator
On/Off, Spring Return, 24 VAC/DC
800-543-9038 USA 866-805-7089 CANADA 203-791-8396 LATIN AMERICA / CARIBBEAN
Date created, 02/16/2017 - Subject to change. © Belimo Aircontrols (USA), Inc.

Summary

Technical Data

Power Specifications

Details electrical power requirements, including supply voltage, running and holding consumption, and transformer sizing.

Mechanical and Performance Data

Covers shaft diameter, electrical connection, overload protection, rotation angle, torque, and running times for motor and fail-safe.

Environmental and Safety Ratings

Includes humidity, ambient/storage temperature ranges, housing rating, agency listings, and noise levels.

Application and Operation

Application Overview

Describes the actuator's use for On/Off, fail-safe control of HVAC dampers, including sizing and mounting.

Operating Principles

Explains the true spring return operation, torque consistency, rotation range, stall capability, and reduced power consumption.

Dimensions and Accessories

Product Dimensions

Provides a diagram with detailed measurements for the actuator in inches and millimeters.

Available Accessories

Lists various accessories for shaft extension, mounting, and control, such as clamps, ball joints, and brackets.

Specifications and Wiring

Typical Specification Requirements

Defines requirements for direct coupling, fail-safe operation, torque, rotation, overload protection, and agency approvals.

Wiring Diagrams and Safety

Illustrates wiring connections and provides critical safety warnings for working with live electrical components.

Overview

The Belimo LF24 US is a damper actuator designed for on/off, spring return operation in HVAC systems, providing reliable fail-safe control of air dampers. This actuator is specifically engineered for applications requiring a positive close-off on airtight dampers, ensuring consistent performance even in critical situations. Its primary function is to open or close dampers based on an on/off control signal, with the added safety feature of a spring return mechanism that drives the damper to a predetermined fail-safe position (either open or closed) in the event of power loss. This fail-safe capability is crucial for maintaining system integrity and safety, for example, by preventing smoke spread in fire safety systems or ensuring proper ventilation in critical environments.

The LF24 US actuator is designed for direct coupling to a damper shaft, eliminating the need for complex crank arms or linkages. This simplifies installation and reduces potential points of failure. It can accommodate round damper shafts ranging from 3/8" to 1/2" in diameter, with the shaft centered at delivery. For larger shafts up to 3/4", an optional K6-1 accessory can be used. The universal clamp mechanism ensures a secure and straightforward attachment. For applications where direct coupling is not feasible, various accessories such as crank arms and mounting brackets are available to facilitate alternative installation methods.

A key usage feature of the LF24 US is its true spring return operation. Unlike some actuators that rely on electronic fail-safe mechanisms, this device uses a mechanical spring to return the damper to its fail-safe position. This provides a highly reliable and consistent torque to the damper, regardless of whether power is applied to the actuator or not. This mechanical reliability is a significant advantage in applications where fail-safe operation is paramount. The actuator offers a maximum rotation angle of 95 degrees, providing ample range for most damper control requirements. A visual position indicator, graduated from 0 to 95 degrees, allows for easy monitoring of the damper's current position, with 0 degrees representing the full spring return position.

The LF24 US is designed for robust performance and durability. It features electronic overload protection throughout its 0 to 95-degree rotation range, meaning the actuator can be stalled anywhere within its normal rotation without the need for mechanical end switches. This protects the motor from damage due to over-rotation or obstructions, enhancing the actuator's lifespan and reducing maintenance needs. The actuator is also double insulated, which eliminates the requirement for an electrical ground connection, simplifying wiring and enhancing safety.

Power consumption is optimized in the LF24 US. While running, the actuator consumes 5W, but in holding mode, the power consumption is reduced to 2.5W. This efficiency helps to lower operational costs and minimize the environmental impact. The actuator operates on a 24 VAC/DC power supply, making it compatible with common HVAC control systems. It can tolerate a wide range of ambient temperatures, from -22°F to 122°F (-30°C to 50°C), and storage temperatures from -40°F to 176°F (-40°C to 80°C), making it suitable for diverse environmental conditions. It also maintains performance in up to 95% RH non-condensing humidity.

From a maintenance perspective, the LF24 US is designed to be largely maintenance-free. Its robust construction, including a zinc-coated steel housing rated NEMA 2 and IP54, protects internal components from dust and moisture, contributing to its long-term reliability. The electronic overload protection further reduces the likelihood of internal damage, minimizing the need for repairs. The use of high-quality materials and adherence to ISO 9001 quality standards ensure a durable and dependable product. The actuator's design for direct coupling also means fewer moving parts and linkages to inspect or adjust over time.

The LF24 US offers flexibility in its direction of rotation. Both the motor-driven rotation and the fail-safe spring return rotation can be reversed by simply changing the mounting orientation (CW/CCW), allowing for adaptable installation to suit specific damper configurations. This adaptability simplifies inventory management and provides greater versatility for installers. The actuator's low noise levels, typically less than 50 dB(A) during motor operation and less than 62 dB(A) during fail-safe operation, ensure quiet performance, which is important in noise-sensitive environments within HVAC systems.

In summary, the Belimo LF24 US damper actuator is a reliable, versatile, and low-maintenance solution for on/off, spring return damper control in HVAC applications. Its true mechanical spring return, robust construction, electronic overload protection, and flexible installation options make it a highly effective component for ensuring both operational efficiency and safety in air handling systems.

Belimo LF24 US Specifications