Honeywell ML7284 - User Manual

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PRODUCT DATA

ML7284

Non-Spring Return

Direct Coupled Damper Actuator

APPLICATION

The ML7284 Non-Spring Return Direct Coupled Damper

Actuator provides proportioning control of dampers in heating,

ventilation and air conditioning (HVAC) applications. The

motor accepts a current or a voltage signal from an electronic

controller to position a damper at any chosen point between

fully open and fully closed.

FEATURES

• Mounts directly on 3/8 in. to 5/8 in. (10 to

17 mm) round and square and 3/4 in. (19 mm) round

damper shafts by using the appropriate insert. Most

models are shipped with 1/2 in. insert.

• Provides 150 lb-in. (17 N•m) torque.

• Magnetic coupling eliminates the need for mechanical

stops or limit switch adjustments by limiting stall

torque to 250 lb-in. (28.3 N•m) maximum.

•95° stroke provides necessary compression of rubber/

neoprene gaskets commonly used on 90° low leakage

dampers.

• Manual clutch allows for manual adjustment.

• 92 second synchronous timing can eliminate need for

feedback position indication in closed-loop tempera-

ture control applications.

• Removable splined output hub permits premounting of

hub on damper shaft, providing installation flexibility.

• Includes standard reverse/direct acting rotation switch,

on the outside cover.

• Designed for both single-point and three-point

mounting, to allow installation flexibility.

• Available with or without a time-out feature. Models

without the time-out feature are designed to be used

with intelligent building management system and/or

controller.

• Standard models have two 8 mm by 12 mm long set

screws for securing the damper shaft. Actuator models

available for various shaft sizes that allow damper

shaft to operate centered inside the output hub.

• Models available with 0 to 10 Vdc, 2 to 10 Vdc, and 4 to

20 mA inputs.

• Models available with 2 to 10 Vdc feedback signal.

63-2504-2

Contents

Application .......................................................................... 1

Features .............................................................................. 1

Specifications ...................................................................... 2

Ordering Information ........................................................... 2

Installation ........................................................................... 4

Operation ............................................................................ 7

Checkout ............................................................................. 8

Troubleshooting .................................................................. 8

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The Honeywell ML7284 Non-Spring Return Direct Coupled Damper Actuator is designed for proportional control of dampers in heating, ventilation, and air conditioning (HVAC) applications. It accepts a current or voltage signal from an electronic controller to position a damper at any point between fully open and fully closed.

Function Description:

The ML7284 operates by driving the damper shaft either clockwise (cw) or counter-clockwise (ccw), depending on the damper design. Most actuators are shipped in the fully counter-clockwise position. When used with a proportional controller, the actuator moves towards its fully open position as the input signal increases and towards its fully closed position as the input signal decreases. The actuator stops when the input signal reaches the desired proportional control point. A rotation reversal slide switch on the side of the actuator housing allows for easy reversal of the actuator's rotation. For example, in the direct position, 2 volts corresponds to closed and 10 volts to open, while in the reverse position, 2 volts corresponds to open and 10 volts to closed.

The ML7284D and ML7284F models include a time-out function that removes power from the actuator submotor if the actuator remains in the fully open or fully closed position for longer than a nominal 5 minutes. This feature helps to extend the actuator's life.

Important Technical Specifications:

Torque: Provides 150 lb-in. (17 N•m) torque. Stall torque is limited to 250 lb-in. (28.3 N•m) maximum.
Power Input: 24 Vac ± 20%, 50/60 Hz.
Power Consumption: 6.0 VA at 24 Vac for ML7284A-C models; 6.5 VA at 24 Vac for ML7284D,F models.
Actuator Stroke: 95° Nominal ± 3°, mechanically limited. The 95° stroke provides necessary compression for rubber/neoprene gaskets commonly used on 90° low leakage dampers.
Actuator Timing (at 90° Stroke): 92 ± 2 seconds synchronous at 60 Hz from -4°F to 140°F; 110 ± 2 seconds synchronous at 50 Hz from -4°F to 140°F. Non-synchronous below -4°F. The 92-second synchronous timing can eliminate the need for feedback position indication in closed-loop temperature control applications.
Ambient Temperature Range: -40°F to +140°F (-40°C to +60°C).
Storage Temperature: -30°F to 150°F (-40°C to 65°C).
Humidity: 5 to 95 percent relative humidity, noncondensing.
Device Weight: 3.0 lb (1.36 kg).
Noise Rating: 45 dBA maximum at 1 meter.
Actuator Design Life: 100,000 full stroke cycles.
Repositions: 2,000,000 minimum.
Control Input Specifications: 2 to 10 Vdc, 0 to 10 Vdc, or 4 to 20 mA. Input impedance is 100K ohms.
Feedback Signal: 2-10 Vdc (available on some models).
Auxiliary Switch Ratings (for ML7284C,F models): 24 Vac, 3 AFL, 18 ALR, 1A Pilot Duty. These models have two nonadjustable low voltage rated SPDT auxiliary switches factory set to make common to normally open at 12° and 82° rotation from the closed (counter-clockwise) stop.
Approvals: UL873 (UL94-5V Enclosure: Plenum rating), UL Listed (File number E4436, Guide number XAPX), CSA Listed (File number LR95329-17).
Environmental Protection Ratings: NEMA1 standard with damper shaft in horizontal position.

Usage Features:

Mounting Flexibility: Mounts directly on 3/8 in. to 5/8 in. (10 to 17 mm) round and square, and 3/4 in. (19 mm) round damper shafts using appropriate inserts. Most models are shipped with a 1/2 in. insert. Removable hub inserts accommodate specific damper shaft sizes, and some models contain an assembly with assorted hub inserts. The removable splined output hub permits pre-mounting of the hub on the damper shaft, providing installation flexibility.
Magnetic Coupling: Eliminates the need for mechanical stops or limit switch adjustments by limiting stall torque.
Manual Clutch: Allows for manual adjustment. The disengage button must be fully depressed when turning the motor output hub by hand or wrench to prevent damage to the gear train. Disengaging with a load on the actuator can damage the gear train.
Position Indicator: A position indicator mounted on the actuator hub shows the shaft position and can be removed and turned to provide proper position indication, indexed to show open or closed using 90° detents.
Mounting Options: Designed for both single-point and three-point mounting. Single-point mounting typically uses a mounting bracket (included with most models) when the actuator is mounted on the damper shaft. Three-point mounting is used for foot mounting or internal duct mounting when direct shaft coupling is not possible.
Shaft Centering: Standard models have two 8 mm by 12 mm long set screws for securing the damper shaft. Actuator models are available for various shaft sizes that allow the damper shaft to operate centered inside the output hub.
Conduit Fittings: The plastic housing has two tapped holes for 1/2 in. conduit fittings.

Maintenance Features:

Installation: The actuator should be installed in a location free from acid fumes or other deteriorating vapors, and not subject to escaping gas or other explosive vapors that could be ignited by a spark. Adequate clearance for mounting accessories and servicing should be provided.
Wiring: All wiring must comply with local electrical codes, ordinances, and regulations. The ML7284 is designed for use with a Class 2 power supply. Voltage and frequency of the transformer used must correspond with the characteristics of the motor and those of the power supply.
Troubleshooting: A comprehensive troubleshooting guide is provided to address issues such as improper operation, incorrect wiring, binding, and actuator or damper malfunction. It emphasizes checking power supply, control signal, reversing switch position, and ensuring free movement of the damper shaft and actuator hub.