Honeywell SPRING RETURN ML6275 - Manual (Page 9)

63-2493—1 9
ML6275 SPRING RETURN DIRECT COUPLED ROTARY ACTUATOR
OPERATION
The ML6275 Direct Coupled Actuator is designed to be used
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
starting position. The actuator is designed for reversible
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.
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.
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.
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.
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.
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.
WHITE/RED
WHITE/BLUE
WHITE/YELLOW
BLACK/RED
BLACK/BLUE
BLACK/YELLOW
AUX. SWITCHES
3A, 120 VAC
12°
82°
M7227A
Fig. 9. ML6275C,F wiring for auxiliary switches.
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.
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.
Fig. 11. Common transformer with one controller output
and two actuators.
L1
(HOT)
L2
1
1
BLUE
YELLOW
RED
BLACK
ML6275
BLUE
YELLOW
RED
BLACK
ML6275
M9953A
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
CONTROLLER
CONTROLLER
Fig. 10. Common transformer with two controller outputs
and two actuators.
L1
(HOT)
L2
1
1
BLUE
YELLOW
RED
BLACK
ML6275
ML6275
BLUE
YELLOW
RED
BLACK
M7758
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
CONTROLLER