For two-position operation of dampers or valves in
heating, ventilating and air-conditioning systems and
similar applications where return to normal position is
not required.
These unidirectional actuators (clockwise rotation)
require a three-wire control circuit; SPDT snap-acting
switch or its equivalent such as a thermostat, pressure
switch or relay. A built-in cam operated, snap-acting,
adjustable SPDT auxiliary switch is standard. It is
factory set to make at mid-stroke. One contact closes
at end of stroke; other contact closes at end of next
stroke.
MC-351, 421, 431, MC-4311
Three-Wire, Two Position Actuators
General Instructions
MC-xxx
(Standard Actuator)
Features
• 24, 120, and 240 Vac models
• Equipped with SPDT auxiliary switch
• Actuator has a rugged die cast aluminum housing
with two 1/2” conduit openings
• Hazardous location actuator housing has two 3/4"
pipe taped openings for rigid metal conduit
connection
• Oil immersed gear train
• Requires a three wire control circuit SPDT
snap-acting or equivalent
Options
Available 24, 120, 208, 240 Vac; 50 or 60 Hz. 50 Hz
specify MC5-xxx. For hazardous locations, specify
MC6-xxx (60 Hz), MC7-xxx (50 Hz). Actuators factory
assembled, UL Listed, cUL Listed.
for Geartrain Actuators General Instructions
F-27441
SPECIFICATIONS
Control Circuit: Three Wire SPDT snap-acting switch or equivalent.
Shaft Rotation: Unidirectional clockwise 180° when power is applied.
Auxiliary Switch: Adjustable SPDT is standard. Factory set to make (or break) at mid stroke.
Running, 5.8A at 120 Vac, 2.9 at 240 Vac
Locked Rotor: 34.8 at 120 Vac, 17.4 at 240 Vac
Non-inductive, 12A at 120 Vac, 6 at 240 Vac.
Environment:
Ambient temperature limits: Shipping and storage -40 to 136 °F (-40 to 58 °C)
Operating -40 to 136 °F (-40 to 58 °C).
Humidity: 5 to 95% RH, non-co ndensing.
Locations: NEMA 1. Optional NEMA 4 with AM-363 gasket, or hazardous service locations
N.E.C., Class 1, Groups C and D, and Class 2, Groups E, F, and G.
Connections: Coded screw terminals.
Options: Hazardous locations specify MC6-351, 421, or 431 (60 hz), MC7-4311 (50 hz).
Agency Listing: UL File #E9429 standard models.
UL File #29291 Hazardous location models. Temperature code T6 for hazardous housing.
Class 1, Groups C & D, and Class 2, Groups E, F, and G hazardous locations; ref er to EN-56 -2, F-18451. Hazardou s locatio n valve actuato rs can also be used
for hazardous location damper applications.
b
Models for hazardous locations are only available as fa ctory-built enclosure/act uator asse mblies. See st a ndard actuat or p art n umber wiring di agrams f or wiring
terminations.
c
Damper ratings are nominal and based on standard (not low leakage) dampers at 1" (25.4 mm) W.C. static pressure and 2000 FPM (10 ml/S) velocity.
d
Not cUL approved.
Nominal Damper
Sq. Ft. (m2)
Parallel
Blade
Opposed
c
Area
Blade
ACCESSORIES
Damper Linkage Accessories (See Figure-1)
AM-111Crank arm for 5/16" diameter damper shaft
AM-112Crank arm for 3/8" diameter damper shaft
AM-113Crank arm for actuator or 1/2" diameter damper shaft
AM-115Crank arm for 7/16" diameter damper shaft
AM-116Splined crank arm for actuator
AM-122Linkage connector straight type
AM-123Damper clip
AM-1255/16" diameter x 20" damper rod
AM-125-048 5/16" diameter x 48" damper rod
AM-132Ball joint connector
AM-161Damper linkage kit
AM-161-1Damper linkage kit
AM-30190 degree mounting bracket
Valve Linkage Accessories (See Figure-4)
AV-330Valve linkage for 2-1/2" & 3" VB-9323
AV-352Valve linkage for 2-1/2" to 6" VB-9213 or VB-9313 valve bodies and 4" to 6" for VB-9323
AV-393Valve linkage for 1/2" to 2" VB-7xxx and 1/2" to 1-1/4" VB-92x3 or VB-93x3
AV-394Valve linkage for 1-1/2" & 2" VB-92x3 or VB-93x3 (discontinued)
AV-396Valve linkage for 2-1/2" to 4" VB-9213 or VB-9313
Valve Linkage Hazardous Location Accessories (See Figure-5)
AV-293 Valve linkage for 1/2" to 2" VB-7xxx series for hazardous locations
AV-296 Valve linkage for 2-1/2" and 3" VB-9xxx (bronze) series for hazardous location
Make all electrical connections in compliance with the job wiring diagram and the national and
local electric codes. Typical connections are shown in (Figure-2).
Figure-1 Damper Linkage Accessories.
Figure-2 External Wiring for Heating Application.
PRE-INSTALLATION
The MC actuators are shipped without mounting hardware or linkage. In damper applications,
crank arms (AM-113), connectors (AM-122 or AM-132), link rods (AM-125) and mounting
brackets (AM-301) will be required. In valve applications, a valve body and AV type linkage will
be required.
Before installing the actuator, check for bent or broken parts or oil leaks. Actuators may be
connected to power supply to check operation prior to installation.
INSTALLATION
RequirementsPreferred mounting for the actuator is in the upright position, but other positions are acceptable.
Adjustable speed units should never be mounted upside down or with the output shaft pointing
upward. Allow six inches clearance above the actuator wiring compartment. If an AM type
mounting bracket is not used, the base of the actuator may be used as a template for marking
mounting holes.
ProcedureActuator may be used in damper and valve control applications. Figure-3 illustrates linkage
operating an arm through a 90° arc. To fasten damper linkage proceed as follows.
Figure-3 180° Actuator Rotation Driving a Damper
Rotation of 90°.
Damper
Installation
1. Fasten linkage connector at end of damper crank arm.
2. Fasten linkage connector at punch mark on actuator crank arm (about .707 of the radius).
3. Move damper to normal position and clamp connecting link to connectors.
4. Check adjustment for proper operation by running actuator and driven shaft between limits
of travel.
Caution: If crank arm does no t provide proper travel, reset connecting link in linkage
connector. Never attempt to turn the actuator shaft with a wrench or a crank. This may damage
the gears.
Valve InstallationInstall all valves with pressure under seat. Refer to flow arrow on body or piping information on
valve body tag. Three way mixing valves should be installed with two inlets and one outlet. Three
way diverting valves should be installed with one inlet and two outlets.
To assemble an actuator to a valve, refer to detailed instructions on AV-3xx General Instruction
Sheet, F-19068 or AV-29x Series Hazardous Location Valve Linkage for Geartrain Actuators
General Instructions, F-27441.