ML6275
Spring Return
Direct Coupled Rotary Actuator
PRODUCT DATA
FEATURES
•
Mounts directly on horizontal 3/8 in., 1/2 in., and
5/8 in. round and square damper shafts by using
the appropriate insert. Most models are shipped with
1/2 in. insert.
•
•
Provides 25 lb-in. running and spring return torque.
Magnetic coupling eliminates the need for mechanical
stops or limit switch adjustments by limiting stall
torque to 60 lb-in. maximum.
•
•
95° stroke provides necessary compression of rubber/
neoprene gaskets commonly used on 90° low leakage
dampers.
88 second synchronous timing can eliminate need for
feedback position indication in closed-loop
temperature control applications.
•
•
Removable splined output hub permits premounting of
hub on damper shaft, providing installation flexibility.
Reversible mounting allows actuator to be used for
either clockwise (cw) or counterclockwise (ccw)
spring rotation.
•
•
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.
Standard one-meter cable with color-coded leadwires
allows external wire connections with 1/2 in. conduit
connectors.
APPLICATION
•
The ML6275 Spring Return Direct Coupled Rotary Actuator is
a floating control motor with an internal, electrically isolated
feedback potentiometer that can be used with controls that
provide switched or floating single pole double throw (spdt)
control output to operate dampers in heating, ventilation, and
air conditioning (HVAC) applications. The feedback potentio-
meter provides indication of the motor output hub position and
can be used for rebalancing an internal control circuit.
•
•
Two or more actuators can be mounted on one
damper shaft to increase output torque for use on
dampers larger than eight square feet.
Contents
General ...............................................................................
Features ..............................................................................
Specifications ......................................................................
Ordering Information ...........................................................
Installation ...........................................................................
Operation ............................................................................
1
1
2
2
4
9
Checkout ............................................................................. 11
Copyright © 1995 Honeywell Inc.
•
All Rights Reserved
63-2493-1
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ML6275 SPRING RETURN DIRECT COUPLED ROTARY ACTUATOR
1-5/32 (29)
6-25/32 (173)
1-17/32 (39)
3-1/16
(79)
8-9/32 (210)
3-29/32
(99)
23/32
(18)
3-15/16 (100)
1-21/32
(42)
3-1/2
(89)
1-5/8
(41)
1-9/32
(32)
CLEARANCE
REQUIRED
FOR SPLINED
HUB MOUNTING
1/2 (13)
3-29/32
(99)
1-13/32
(36)
1-3/32
(28)
135o
15o
13/32
(10)
13/64 (5)
3/4 (19)
5/16
(8)
3/8
(10)
1-13/32 (36)
4-13/32 (112)
1-5/8 (41)
10-13/32 (264)
M8257
MOUNTING BRACKET
Fig. 1. Approximate dimensions of ML6275 Spring Return Direct Coupled Actuator and mounting bracket in in. (mm).
Accessories:
Environmental Protection Ratings:
205753 Hub Sleeve, 3/8 in
205758 Hub Sleeve, 5/8 in
205820A 3-Point Mounting Kit
205830A Crank-Arm Accessory
205840A Tandem Mount Kit
205850A End Stop Kit
NEMA1 standard with damper shaft in horizontal position
Mounting Tab:
For use with Universal mounting bracket
3
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ML6275 SPRING RETURN DIRECT COUPLED ROTARY ACTUATOR
INSTALLATION
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.
When Installing this Product…
ᕡ Read instructions carefully. Failure to follow them could
damage the product or cause a hazardous condition.
ᕢ Check ratings and description given in the specifications
to make sure the product is suitable for your application.
ᕣ Installer must be a trained, experienced service
technician.
Preparation
Before installing the ML6275 on the damper shaft, determine
the opening direction of the damper shaft to determine the
correct spring return rotation and correctly connect the wiring.
The ML6275 can be mounted to provide clockwise or
counterclockwise spring return. Reverse the actuator if
necessary to provide the desired spring action.
ᕤ After 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.
Installation
Installing the Actuator and Mounting Bracket
2. Never turn motor output hub by hand or wrench.
3. Do not install actuator in areas with acid fumes or
other deteriorating vapors that might 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.
(Single Point Mounting)
When the direction of the damper shaft rotation is determined
(either cw
or ccw
), proceed as follows:
ᕡ Place the ML6275 Direct Coupled Actuator over the
damper shaft.
ᕢ Position the actuator for best access to the actuator
damper shaft locking screw.
ᕣ Install the mounting bracket (see Fig. 2) and adjust it to
support the actuator at the correct height. Mark the
screw holes for installing the mounting bracket on the
damper housing.
ᕤ Remove the mounting bracket and actuator.
ᕥ Drill or center punch the starting holes for the mounting
bracket screws (or use no. 10 self-tapping sheet metal
screws).
Location
Install the actuator in any location free from acid fumes or
other deteriorating vapors that might 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.
ᕦ Place the actuator and mounting bracket back into
position over the damper shaft and install the mounting
bracket screws.
ᕧ Tighten the two 8 mm by 12 mm long set screws firmly
against the damper shaft (maximum tightening torque is
100 lb-in.).
Mounting
The ML6275 Direct Coupled Actuator is designed to operate
a damper by driving the damper shaft either cw
ccw depending on damper design. All actuators are
shipped in the fully closed position.
or
0
9
0
6
0
3
The ML6275 Direct Coupled Actuator is designed for single-
point mounting when using an adapter bracket. Single-point
mounting is typically used when the actuator is mounted on
the damper frame.
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 support the actuator at the correct height.
The ML6275 Direct Coupled Actuator can also be three-point
mounted using the two front gear housing slots and the
adapter bracket. Two screws are secured through the two
front gear housing slots and the adapter bracket positioned to
secure the rear of the actuator. 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.
M9386
Fig. 2. Installing mounting bracket on ML6275 Direct
Coupled Actuator.
4
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ML6275 SPRING RETURN DIRECT COUPLED ROTARY ACTUATOR
The ML6275 Direct Coupled Actuator has a reversible output
Installing the Actuator for Three-Point Mounting
hub. The hub is factory-mounted on the top of the actuator
gear housing. When attaching to damper shafts less than 3.5
in. (76 mm) long, or for ease of mounting, the output hub can
be mounted to the inside of the actuator gear housing. See
Fig. 3. Be careful when removing the retaining ring that
secures the output hub to the actuator housing. Use a
flatheaded screwdriver to pry the ring loose.
The ML6275 Direct Coupled Actuator is designed with
removable hub sleeves to accommodate specific damper
shaft sizes. Proper sleeve selection is necessary when three-
point mounting is used to avoid excessive strain on the output
gear. Most ML6275 Actuators are shipped with a 1/2 in. hub
sleeve. For field use, several hub sleeve sizes are available.
See the Accessories listing in the Specifications section. Shaft
sizes are stamped on the sleeves.
Other possible mounting configurations and standard
connections are shown in Fig. 4 through 7.
The ML6275 Direct Coupled Actuator can be mounted directly
on the motor shaft with the actuator in any position when the
actuator housing is parallel with the damper housing or frame.
(See Fig. 7.)
2
6
1
3
60
30
90
DETENT
INSERT
60
30
0
4
5
.500
INDICATOR
. 5 0 0
DETENTS
M7228
Fig. 3. Mounting hub to inside of actuator.
5
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ML6275 SPRING RETURN DIRECT COUPLED ROTARY ACTUATOR
0
6
0
3
0
9
0
6
0
3
0
1
INDICATOR
DETENTS
1
COUNTERCLOCKWISE SPRING ROTATION ARROW
M7230A
Fig. 4. ML6275 Actuator mounted for counterclockwise spring rotation with output hub inside actuator. (NOTE: NEMA
rating applies only with damper shaft in horizontal position.)
6
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ML6275 SPRING RETURN DIRECT COUPLED ROTARY ACTUATOR
0
6
0
0
3
9
0
6
0
3
.500
. 5 0 0
M7229
Fig. 5. Standard direct coupled mounting of ML6275 to a damper with counterclockwise spring rotation.
7
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ML6275 SPRING RETURN DIRECT COUPLED ROTARY ACTUATOR
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 ML6275 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. See Fig. 8 for a typical wiring
connection.
60
30
90
60
30
.500
The ML6275 has an aluminum die cast housing with two
integral cast bosses on the end of the device, tapped for
1/2 in. conduit fittings. Some models are shipped with a water
seal in the conduit opening. If conduit is needed, remove the
seal before routing the cable.
. 5 0 0
ML6275 Models with Factory-mounted Auxiliary
Switches (See Fig. 9)
ML6275C,F models have two nonadjustable line voltage rated
spdt auxiliary switches that are factory set to make common
to normally open at 12° and 82° rotation from the
counterclockwise stop. See Fig. 9.
IMPORTANT:
TO JUNCTION
BOX (UP TO
3 FT AWAY)
Actuators driving in parallel may not be synchronized
with each other. In normal operation, when all
actuators are driven to the fully open or fully closed
position, the actuators are again synchronized.
MOUNTING
BRACKET
M7231
FEEDBACK WIRING
ORANGE (OPEN)
Fig. 6. ML6275 Actuator standard electrical connection.
TAN
3
GREEN (CLOSED)
ML6275
OPEN
BLUE
MOTOR
CLOSE
YELLOW
OPTIONAL
TIME OUT
2
24 HOT
RED
POWER
SUPPLY
1
SPRING
CONTROL
60
L1
30
90
60
(HOT)
24 VAC
24 GND
BLACK
30
0
L2
500
5 0 0
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
2
3
TIME-OUT FUNCTION AVAILABLE WITH ML6275D,F MODELS.
M9954A
500 OHM POTENTIOMETER.
Fig. 8. ML6275 typical wiring diagram.
M9384
Fig. 7. ML6275 Actuator can be mounted in any position.
(NOTE: NEMA rating applies only with damper shaft in
horizontal position.)
8
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ML6275 SPRING RETURN DIRECT COUPLED ROTARY ACTUATOR
WHITE/RED
12°
AUX. SWITCHES
3A, 120 VAC
OPERATION
WHITE/BLUE
WHITE/YELLOW
BLACK/RED
The ML6275 Direct Coupled Actuator is designed to be used
82°
in ventilating and air conditioning installations to operate
dampers, ventilation flaps and louvers requiring up to 25 lb-in.
torque. If the power fails, the actuator will spring return to the
BLACK/BLUE
BLACK/YELLOW
M7227A
starting position. The actuator is designed for reversible
Fig. 9. ML6275C,F wiring for auxiliary switches.
mounting. Arrows are molded into the covers to show the
spring return direction. The larger cover shows a
counterclockwise (ccw) spring rotation; the smaller cover
shows a clockwise (cw) spring rotation.
Connecting ML6275 Actuators in Parallel
ML6275 Actuators can be stacked on one damper shaft to
increase the output torque required to drive dampers larger
than eight square feet.
The ML6275 Direct Coupled Actuator is operated by an spdt
floating controller. When using an spdt floating controller, the
actuator will be driven toward its fully open position when the
controller makes R to B and toward the fully closed position
when the controller makes R to W. It stops when neither
contact is made.
To make sure proper phasing occurs, connect all four
leadwires (red, black, yellow and blue) in parallel. The
number of actuators that can be wired in parallel is
dependent on the transformer VA rating. Make certain that
the connected load does not exceed the current capacity of
the controller/thermostat. See Fig. 10 and 11.
IMPORTANT
The ML6275 is designed to respond to
instantaneous contact closures from a DDC
Controller. Be careful not to short cycle the actuator.
Unstable damper control can cause premature
actuator failure.
ML6275
CONTROLLER
BLUE
YELLOW
1
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 four distinct
positions where the indicator can be placed. The indicator can
be removed (by first removing the output hub) to provide
proper damper orientation. The indicator can be indexed to
show cw or ccw open or closed, using the detents that are
90° apart. See Fig. 12. If the spring return position is the open
position, rotate the indicator until it points to 90 on the scale. If
the spring return position is the closed position, rotate the
indicator until it points to zero on the scale. A detent can be
felt at both stops; the detents maintain the indicator position.
RED
L1
(HOT)
BLACK
L2
ML6275
CONTROLLER
BLUE
YELLOW
RED
BLACK
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
M9953A
The ML6275D and ML6275F models provide a timeout
function that removes power from the actuator submotor if the
actuator remains in one position (closed, open, or any
intermediate position) for longer than a nominal 100 seconds.
This time-out function helps to extend actuator life.
Fig. 10. Common transformer with two controller outputs
and two actuators.
ML6275
IMPORTANT
The ML6275 was designed to provide 7500 spring
returns. Therefore, the actuator can be unpowered
daily for night shutdown control. However, rapidly
cycling the actuator by removing control voltage will
lead to premature spring failure.
CONTROLLER
BLUE
YELLOW
1
RED
L1
(HOT)
BLACK
L2
ML6275
BLUE
YELLOW
RED
BLACK
1
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
M7758
Fig. 11. Common transformer with one controller output
and two actuators.
9
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ML6275 SPRING RETURN DIRECT COUPLED ROTARY ACTUATOR
FULLY COUNTERCLOCKWISE SPRING RETURN INDICATOR START POSITIONS
POINTER AT 90°
POINTER AT 0°
90
90
60
60
60
60
30
0
30
0
30
0
30
0
DETENT IN INSERT
DETENT IN INSERT
DRIVE CLOCKWISE TO CLOSE
(REVERSE ACTING)
DRIVE CLOCKWISE TO OPEN
(DIRECT ACTING)
FULLY CLOCKWISE SPRING RETURN INDICATOR START POSITIONS
POINTER AT 90°
POINTER AT 0°
90
90
60
60
60
60
30
0
30
0
30
0
30
0
M7235
DETENT IN INSERT
DETENT IN INSERT
DRIVE COUNTERCLOCKWISE
TO CLOSE (REVERSE ACTING)
M7235B
DRIVE COUNTERCLOCKWISE
TO OPEN (DIRECT ACTING)
Fig. 12. ML6275 indicator start positions.
10
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ML6275 SPRING RETURN DIRECT COUPLED ROTARY ACTUATOR
4. Connect 24 Vac to the appropriate leadwires (red to
blue or red to yellow) to move the damper to the
opposite position. The ML6275 should drive the
CHECKOUT
The ML6275 Direct Coupled Actuator can be checked out
either directly or by using a controller.
damper.
5. If the actuator does not run, verify that the actuator is
properly installed for either cw
rotation.
6. If the actuator operates in the opposite direction than
desired, reverse the blue and yellow leadwires.
7. If the actuator is correctly installed and still does not
run, replace the actuator.
or ccw
Important
When power is interrupted, the actuator returns to
the normal starting position using the spring
mechanism. When power is restored, the controller
input will not operate the actuator until the spring is
fully wound and locked. The spring winding process
takes approximately 100 seconds, depending on the
number of degrees of spring return remaining at
power interrupt (eg, 10° of spring return remaining
takes ten seconds). (If the actuator is not in the
closed position, it will run to the closed position while
the spring is winding.) Once the spring is locked in
its fully wound position, the actuator responds to
inputs across the red-to-blue or red-to-yellow
leadwires.
Controller Checkout
1. Adjust the setpoint of the controller to call for cooling.
Observe the actuator.
2. If the damper is closed, it should begin to open.
3. If the damper remains closed, move the setpoint of the
controller farther below the room temperature.
4. If the damper still does not move, check for the
presence of 24 Vac in the input.
5. Make sure the actuator spring is fully wound by
applying power for at least 100 seconds.
6. If 24 Vac is present and the actuator does not operate,
reverse the controller leadwires to determine if the
device was miswired.
7. If the wiring is correct and 24 Vac is present on the
input terminals but the actuator does not run, replace
the actuator.
Direct Checkout
1. Mount the actuator for the required application (either
cw
or ccw
rotation to open the damper).
2. Check the damper position and make sure that 24 Vac
is present on the red and black leadwires.
3. Make sure the actuator spring is fully wound and locked
by applying power for at least 100 seconds.
11
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63-2493—1
Home and Building Control
Honeywell Inc.
1985 Douglas Drive North
Golden Valley, MN 55422
Home and Building Control
Honeywell Limited-Honeywell Limitée
740 Ellesmere Road
Helping You Control Your World
Scarborough, Ontario
QUALITY IS KEY
M1P 2V9
63-2493—1 G.R. Rev. 11-95 Printed in U.S.A.
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