Honeywell ML7284 Operation manual

PRODUCT DATA
Copyright © 1996 Honeywell Inc. • All Rights Reserved
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 10Vdc, 2 to 10 Vdc, and 4 to
20 mA inputs.
• Models available with 2 to 10Vdc feedback signal.
63-2504-2
Contents
Application .......................................................................... 1
Features .............................................................................. 1
Specifications ...................................................................... 2
Ordering Information ........................................................... 2
Installation ........................................................................... 4
Operation ............................................................................ 7
Checkout ............................................................................. 8
Troubleshooting .................................................................. 8

ML7284 NON-SPRING RETURN DIRECT COUPLED DAMPER ACTUATOR
63-2504—2 2
SPECIFICATIONS
Models:
ML7284:Non-SpringReturnDirectCoupledDamperActuators.
ML7284A: High Torque (150 lb-in.) Direct Coupled Damper
Actuator without auxiliary switches or time-out function.
ML7284C: High Torque (150 lb-in.) Direct Coupled Damper
Actuator with two low voltage rated auxiliary switches
and without time-out function.
ML7284D: High Torque (150 lb-in.) Direct Coupled Damper
Actuator without auxiliary switches and with time-out
function.
ML7284F: High Torque (150 lb-in.) Direct Coupled Damper
Actuator with two low voltage auxiliary switches and
with time-out function.
Electrical Ratings:
Power Input: 24 Vac ±20%, 50/60 Hz.
Power Consumption:
ML7284A-C: 6.0 VA at 24 Vac.
ML7284D,F: 6.5 VA at 24 Vac.
Auxiliary Switch Ratings: 24 Vac, 3 AFL, 18 ALR, 1A Pilot
Duty.
Cable Ratings:
Control: Standard models include nonplenum UL/CSA
rated, 30V, 60°C, 20 gauge cable.
Auxiliary Switch: UL/CSA rated 300V 90°C, 18 gauge.
Torque Ratings at RatedVoltages:
Lift and Hold Minimum: 150 lb-in. (17 N•m).
Breakaway Minimum: 150 lb-in. (17 N•m).
Stall Minimum: 150 lb-in. (17 N•m).
Stall Maximum: 250 lb-in. (28.3 N•m).
Torque Deratings at 24 ±20% Vac:
150 lb-in. from -20°F to 95°F (-29°C to +35°C).
133 lb-in. from 95°F to 140°F (35°C to 60°C).
150 lb-in. from -40°F to -20°F (-29°C to -34°C) at 24 Vac
+20% only.
Actuator Stroke:
95°Nominal ±3°, mechanically limited.
ActuatorTiming 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.
AmbientTemperature Range:
-40°F to +140°F (-40°C to +60°C).
StorageTemperature:
-30°F to 150°F (-40°C to 65°C).
Humidity:
5 to 95 percent relative humidity, noncondensing.
Mounting:
Mounts directly on 3/8 in. to 3/4 in. (12 to 19 mm) round or
square damper shaft. Minimum shaft length required:
• 2.5 in. (64 mm) when the shaft attachment is made on
the side of the actuator opposite the duct;
• 0.65 in. (16 mm) when the hub is mounted on the shaft
before the actuator is installed.
Most actuators are shipped with specifically sized hubs.
Some models contain an assembly with assorted hub inserts.
Mounting bracket is included with most models.
Dimensions:
See Fig. 1.
Device Weight:
3.0 lb (1.36 kg).
Noise Rating:
45 dBA maximum at 1 meter.
Position Indicator:
Mounted on actuator hub.
Actuator Design Life:
Full Stroke Cycles: 100,000.
Repositions:
2,000,000 minimum.
Control Input Specifications:
2 to 10 Vdc, 0 to 10 Vdc, or 4 to 20 mA.
Input Impedance:
100K ohms.
Feedback Signal:
2-10 Vdc.
ORDERING INFORMATION
When purchasing replacement and modernization products from your TRADELINE® wholesaler or distributor, refer to the
TRADELINE® Catalog or price sheets for complete ordering number, or specify:
1. Model number. 2. Application.
If you have additional questions, need further information, or would like to comment on our products or services, please write or phone:
1. Your local Home and Building Control Sales Office (check white pages of your phone directory).
2. Home and Building Control Customer Logistics
Honeywell Inc., 1885 Douglas Drive North
Minneapolis, Minnesota 55422-4386 [phone]
In Canada—Honeywell Limited/Honeywell Limitée, 155 Gordon Baker Road, NorthYork, Ontario M2H 2C9. International Sales
and Service Offices in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France, Germany, Japan,
Mexico, Netherlands, Spain, Taiwan, United Kingdom, U.S.A.

ML7284 NON-SPRING RETURN DIRECT COUPLED DAMPER ACTUATOR
63-2504—2
3
Fig. 1. Approximate dimensions of ML7284 Non-Spring Return Direct Coupled
Damper Actuator and mounting bracket in in. (mm).
9/32 (7)
3 PLACES
1-17/32
(39)
3-3/32 (79)
4 (102)
7/16 (11)
1-1/4
(32)
7-11/16
(196)
8-7/16
(215)
36
(914)
1/2
(12)
5/8 (17)
13/32 (10)
1/2
(13)
3/4
(19) 7/8 (22) 1 (25)
3-5/32
(80)
1/2 (13)
1/2 (13)1-11/16 (43)
2-1/2 (63)
3-5/16 (84)
4-1/2 (114)
5 (127)
6 (152)
1/4 (6)
1
1 REMOVABLE RETAINING RING FOR
REMOVAL OF HUB SLEEVE
M7618B
1/4 (6)
1/8 (3)
2
(51)
15/16
(24)
1-29/32
(48)

ML7284 NON-SPRING RETURN DIRECT COUPLED DAMPER ACTUATOR
63-2504—2 4
Disengaging Cycles:
100
CAUTION
Disengaging (pressing manual release button) with
load on actuator can damage actuator gear train.
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.
Accessories:
205617 Hub insert, 3/4 in. round.
205753 Hub insert, 3/8 in.
205758 Hub insert, 5/8 in.
205820A 3-Point Mounting Kit.
205685 Crank-Arm Accessory.
205850C End Stop Kit.
INSTALLATION
When Installing this Product…
1Read instructions carefully. Failure to follow them could
damage the product or cause a hazardous condition.
2Check ratings and description given in the
specifications to make sure the product is suitable for
your application.
3Installer must be a trained, experienced service
technician.
4After installation is complete, check out product
operation as provided in these instructions.
CAUTION
1. Disconnect power before installation to prevent
electrical shock or equipment damage.
2. Never turn motor output hub by hand or wrench
unless declutch button is fully depressed.
3. Do not install actuator in areas with acid fumes or
other deteriorating vapors that could attack the
metal parts of the actuator.
4. Do not install actuator in areas with escaping gas
or other explosive vapors that could be ignited by
a spark from the actuator or attached
accessories.
Location
Install the actuator in any location free from acid fumes or
other deteriorating vapors that could attack the metal parts of
the actuator. Make sure the location is not subject to escaping
gas or other explosive vapors that could accidentally be
ignited by a spark from the actuator or its attached parts.
Install the actuator in a location that allows enough clearance
for mounting accessories and for servicing.
Mounting
The ML7284 Non-Spring Return Direct Coupled Damper
Actuator is designed to operate a damper by driving the
damper shaft either cw or ccw depending on
damper design. All actuators are shipped in the fully ccw
position.
The ML7284 Non-Spring Return Direct Coupled Damper
Actuator is designed with removable hub inserts to
accommodate specific damper shaft sizes. Proper insert
selection is necessary to avoid excessive strain on the output
gear. Most ML7284 Actuators are shipped with a 1/2 in. hub
insert. For field use, three hub insert sizes are available. See
the Accessories listing in the Specifications section. Shaft
sizes are stamped on the inserts.
The ML7284 Non-Spring Return Direct Coupled Damper
Actuator is designed for single-point mounting when using a
mounting bracket. Single-point mounting is typically used
when the actuator is mounted on the damper shaft.
The ML7284 Non-Spring Return Direct Coupled Damper
Actuator can be mounted directly on the damper shaft with
the actuator in any position.
A mounting bracket (see Fig. 1) is provided with some models
to aid in installing the actuator.The bracket can be bent to
any shape to allow the mounting bracket tab to be centered in
the actuator slot. Install the mounting bracket so that the
mounting bracket tab is centered in the actuator slot.
CAUTION
The mounting bracket must not bind or clamp the
actuator to the duct.The mounting bracket is used to
prevent the actuator housing from rotating.
The ML7284 Direct Coupled Damper Actuator has a
reversible output hub.The hub is factory mounted on the top
of the actuator gear housing. When attaching to damper
shafts lest than 2.5 in. (64 mm) long, or for ease of mounting,
the output hub can be mounted to the back of the actuator
gear housing. See Fig. 3. Be careful when removing the
retaining ring which secures the output hub sleeve to the
actuator housing. Use a flatheaded screw driver to pry the
ring loose. A typical actuator mechanical connection is shown
in Fig. 4; wiring diagrams in Fig. 5 through 8.
The ML7284 Non-Spring Return Direct Coupled Damper
Actuator can also be three-point mounted using the three
frame slots.Three point mounting is used for foot mounting
the actuator or internally mounting the actuator in the duct
when direct shaft coupling is not possible.
CAUTION
Do not use the actuator as a shaft bearing.The
actuator must be used only to supply rotational torque.
To prevent damage to the actuator, avoid any side
loads to the actuator output coupling bearings. Also,
provide clearance for actuator sleeve on the back.

ML7284 NON-SPRING RETURN DIRECT COUPLED DAMPER ACTUATOR
63-2504—2
5
9Tighten the two 8 mm by 12 mm long set screws firmly
against the damper shaft (80-100 lb-in.).
Preparation
Before installing the ML7284 on the damper shaft, determine
the opening direction of the damper shaft (see Fig. 2) to
correctly connect the wiring.
Installation
Installing Actuator and Mounting Bracket
(Single Point Mounting)
1Place the ML7284 Non-Spring Return Direct Coupled
Damper Actuator over the damper shaft.
2Position the actuator for best access to the actuator
damper shaft locking screw.
3Install the mounting bracket (see Fig. 2) and adjust it so
the tab is midway in the actuator slot. Mark the screw
holes for installing the mounting bracket on the damper
housing.
4Remove the mounting bracket and actuator.
5Drill or center punch the starting holes for the mounting
bracket screws (or use no. 10 self-tapping sheet metal
screws, not provided).
6Place the actuator and mounting bracket back into
position over the damper shaft and install the mounting
bracket screws.
7Move damper shaft either fully cw or ccw .
8Fully depress and hold disengage button while moving
actuator hub either fully cw or fully ccw to
match damper shaft. Release disengage button. Fig. 2. Installing mounting bracket on ML7284
Non-Spring Return Direct Coupled Damper Actuator.
NOTE: Install mounting bracket so mounting bracket tab
is centered in actuator slot.
M7619B
REVERSE
DIRECT
ACTUATOR
SLOT
Fig. 3. Mounting hub to back of actuator.
12
12
30
30
0
60
60 90
M7620C
DETENT
INSERT
INDICATOR
DETENTS
DISENGAGE
BUTTON
HUB
SLEEVE
HUB
INSERTS
REVERSE
DIRECT
POSITION
INDICATOR
RETAINING
RING

ML7284 NON-SPRING RETURN DIRECT COUPLED DAMPER ACTUATOR
63-2504—2 6
12°
82°
M7877
COMMON
COMMON
NO
NO
NC
NC
WHT/RED
WHT/BLU
WHT/YEL
BLACK/RED
BLACK/BLU
BLACK/YEL
INTERNAL
AUXILIARY
SWITCH
3A 24VAC
SWITCHES SHOWN AT ACTUATOR CLOSED POSITION
Fig. 6. ML7284 Actuator wiring for auxiliary switches.
Switches shown at actuator closed
(counterclockwise) position.
L1
(HOT)
L2
1
1
RED
BLACK
RED
BLACK
ML7284
ML7284
M7616A
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
PROPORTIONING
CONTROLLER
PROPORTIONING
CONTROLLER
BROWN
WHITE
BROWN
WHITE
FEEDBACK
INPUT
FEEDBACK
INPUT
Fig. 7. Common transformer with two
controller outputs and two actuators.
M7621A
MOUNTING
BRACKET
TO JUNCTION
BOX (UP TO
3 FT AWAY)
30
30
0
60
60 90
12
12
REVERSE
DIRECT
Fig. 4. ML7284 Actuator typical mechanical connection.
M7623A
ML7284
MODULATING
CONTROL
SOURCE
BROWN
WHITE
BLACK
RED
24 VAC
FEEDBACK
INPUT
T1
T2
METER
L1
(HOT)
L2
1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
Fig. 5. ML7284 typical wiring diagram.

ML7284 NON-SPRING RETURN DIRECT COUPLED DAMPER ACTUATOR
63-2504—2
7
L1
(HOT)
L2
1
1
BROWN
WHITE
BROWN
WHITE
RED
BLACK
ML7284
ML7284
RED
BLACK
M7617A
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
PROPORTIONING
CONTROLLER FEEDBACK
INPUT
FEEDBACK
INPUT
Fig. 8. Common transformer with one
controller output and two actuators.
Wiring
CAUTION
Disconnect power supply before wiring to prevent
electrical shock or equipment damage.
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. Standard mechanical connection is shown
in Fig. 4. See Fig. 5 for a typical wiring connection.
The ML7284 has a plastic housing with two tapped holes for
1/2 in. conduit fittings.
ML7284 Models with Factory-mounted Auxiliary
Switches (See Fig. 6)
ML7284C,F models have two nonadjustable low voltage rated
spdt auxiliary switches that are factory set to make common
to normally open at 12°and 82°rotation from the closed
(counter-clockwise) stop. See Fig. 6.
OPERATION
The ML7284 Non-Spring Return Direct Coupled Damper
Actuator is designed to be used in ventilating and air condi-
tioning installations to operate dampers, ventilation flaps and
louvers requiring up to 150 lb-in. torque.
The ML7284 Non-Spring Return Direct Coupled Damper
Actuator is operated by a proportional controller. When using
a proportional controller, the actuator is driven toward its
fully open position when the input signal increases and
toward the fully closed position when the input signal
decreases.The actuator stops when the input signal
reaches the desired proportional control point.
Use the rotation reversal slide switch to reverse the actuator
rotation.The switch is located on the side of the actuator
housing. See Fig. 9.To change the rotation to counter-
clockwise , change the slide switch. Example: In direct
position 2 volts is closed and 10 volts is open. In reverse
position 2 volts is open and 10 volts is closed.
M7830
30
30
0
60
60 90
12
12
ROTATION
REVERSAL
SWITCH
REVERSE
DIRECT
Fig. 9. Location of ML7284 rotation
reversal slide switch.

ML7284 NON-SPRING RETURN DIRECT COUPLED DAMPER ACTUATOR
63-2504—2 8
IMPORTANT
The ML7284 can operate with a DDC controller.Do
not short cycle the actuator. Short cycling of the
actuator can cause premature failure.
The actuator has a position indicator to show shaft position.
As the indicator moves with the shaft, it gives an angular
representation of the damper position.There are two distinct
positions where the indicator can be placed.The indicator
can be removed (by first removing the output hub) and
turned to provide proper position indication.The indicator
can be indexed to show open or closed, using the detents
that are 90°apart. See Fig. 3.
The ML7284D and ML7284F models provide 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 time-out function helps
to extend actuator life.
CHECKOUT
Perform the following checkout procedure for the ML7284
Direct Coupled Damper Actuator.
1Check the actuator position indicator and damper shaft
position to see that they agree.
2Apply 24 Vac to the black (T1) and red (T2) leads.
3Apply minimum control signal (0 Vdc, +2 Vdc, or 4 mA)
to the white (Input) lead with respect to the black (T1)
lead:
• If the reversing switch is in the direct position, the
actuator should drive the damper to the closed
(counterclockwise ) position.
• If the reversing switch is in the reverse position,
the actuator should drive the damper to the open
(clockwise ) position.
4Apply maximum control signal (+10 Vdc or 20 mA) to
the white (Input) lead with respect to the black (T1)
lead.
• If the reversing switch is in the direct position, the
actuator should drive the damper to the open
(clockwise ) position.
• If the reversing switch is in the reverse position,
the actuator should drive the damper to the
closed (counterclockwise ) position.
Helping You Control Your World
Home and Building Control
Honeywell Limited-Honeywell Limitée
155 Gordon Baker Road
North York, Ontario
M2H 2C9
63-2504—2 G. R. Rev. 4-96 Printed in U.S.A.
Home and Building Control
Honeywell Inc.
1985 Douglas Drive North
Golden Valley, MN 55422
TROUBLESHOOTING
If the actuator does not operate properly during the checkout,
perform the following troubleshooting steps. Perform these
steps before replacing the actuator.
1Check actuator label to verify proper power and control
signal requirements for the application.
2Check for presence of 24 Vac at the black (T1) and red
(T2) leads when the actuator should be operating. If the
voltage is not present or is low, check the power supply
and actuator connections.
3Check control signal voltage (or current) for proper
value and polarity at the actuator white (Input) and
black (T1) leads when the actuator should be driving. If
the signal is wrong, not present, or low, check the
controller.The positive (+) signal must go to the white
(Input) lead. If this signal point is negative, change the
control wiring.
4Make sure the feedback wire is not connected to
24 Vac.
5Change the reversing switch if the actuator does not
drive in the desired direction when a control signal is
applied and the wiring is correct.
6Remove power and fully depress and hold the
disengage button while trying to turn the damper shaft
clockwise and counterclockwise . If the
damper shaft turn freely throughout the 90°stroke and
the actuator is installed correctly, replace the actuator.
7If the damper shaft will not turn freely for the full 90°,
check for any binding and make sure the actuator is
loose on its mount bracket to prevent binding. If
necessary, adjust the mounting bracket to prevent
binding.
8If no binding is noticed in the actuator and damper
assembly, remove the actuator and turn the damper
shaft clockwise and counterclockwise . If the
damper does not turn freely, fix or replace the damper.
9If the damper turns, fully depress and hold the
disengage button and turn the actuator hub clockwise
and counterclockwise . If the actuator does not
turn, replace the actuator.
JIf the actuator and damper turn freely, remount the
actuator to the damper following the instructions in the
Installation section. Make sure the actuator does not
bind, and that the damper and actuator are at the same
clockwise or counterclockwise end stop
when they are assembled. Connect all power and
control wiring and repeat the checkout.Troubleshoot if
necessary.