Honeywell ML6421 Operation manual

PRODUCT DATA
63-2515-4
® U.S. Registered Trademark
Copyright © 2002 Honeywell • All Rights Reserved
®
ML6421, ML7421
Non-Spring Return
Electric Linear Valve Actuators
APPLICATION
The ML6421A,B Non-Spring Return Electric Linear Valve
Actuators are suitable for use with low-voltage, single-pole
double-throw (spdt), Series 60 two-position and floating
controllers. These actuators operate standard Honeywell
valves in heating, ventilating, and air conditioning (HVAC)
applications.
The ML7421A,B Non-Spring Return Electric Linear Valve
Actuators are modulating control actuators used with controls
that provide an analog output of 0 to 10 Vdc or 2 to 10 Vdc.
These actuators operate standard Honeywell valves in HVAC
applications. An internal selector plug can be used to reverse
the direction of action.
FEATURES
• Quick and easy installation.
• No separate linkage required.
• 3/4 in. (20 mm) stroke on ML6421A and ML7421A.
• 1-1/2 in. (38 mm) stroke on ML6421B and ML7421B.
• No adjustments required.
• Accurate valve positioning.
• Low power consumption.
• Selectable 0(2) to 10 Vdc or 0(4) to 20 mA input signal
with ML7421.
• Position feedback with ML7421.
• High close-off ratings.
• Direct/reverse acting with ML7421.
• Force-limiting end switches.
• Manual operator.
• Synchronous motor.
• Corrosion-resistant design.
• Maintenance free.
• Conduit connector knockout.
Contents
Application ........................................................................ 1
Features ........................................................................... 1
Specifications ................................................................... 2
Ordering Information ........................................................ 2
Installation ........................................................................ 3
Operation .......................................................................... 6
Checkout .......................................................................... 7

ML6421, ML7421 NON-SPRING RETURN ELECTRIC LINEAR VALVE ACTUATORS
63-2515—4 2
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.
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 Relations
Honeywell, 1885 Douglas Drive North
Minneapolis, Minnesota 55422-4386
In Canada—Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario M1V 4Z9.
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.
SPECIFICATIONS
Models:
Dimensions: See Fig. 1.
Weight: 5.1 lb (2.3 kg).
Electrical Ratings:
Power Input: 24 Vac (+10%, -15%), 60 Hz.
Power Consumption: 11 VA maximum at 24 Vac.
Signal Inputs:
ML6421:
24 Vac across T1 and W: Drives stem downward.
24 Vac across T2 and B: Draws stem upward.
ML7421: 0 to 10 Vdc or 2 to 10 Vdc.
Actuator Material:
Cover: ABS plastic.
Yoke and Base: Diecast aluminum.
Stem Force: 405 lbf (1800N).
Close-off Pressure Ratings: See Table 1.
Cable Entry: Two knockout holes for 1/2 in. conduit standard
on actuator case.
Ambient Ratings:
Temperature:
Ambient Range: 14°F to 122°F (-10°C to +50°C).
Storage Range: -40°F to +158°F (-40°C to +70°C).
Humidity Range: 5 to 95 percent relative humidity,
noncondensing.
Approvals:
Canadian Standards Association Listed.
Underwriter’s Laboratories, Inc. UL94-5V Flame Retardant
(file E181716).
Meets CE requirements.
Protection Standard: IP54.
Accessories:
43191679-101 Single Auxiliary Potentiometer for ML6421A.
43191679-102 Single Auxiliary Potentiometer for ML6421B.
43191679-103 Dual Auxiliary Potentiometer for ML6421A.
43191679-104 Dual Auxiliary Potentiometer for ML6421B.
43191680-102 Dual Auxiliary Switch (for 24 Vac use only).
43196000-001 High Temperature Kit (for actuators with 3/4 in.
stroke). Increases maximum temperature to 428°F (220°C).
43196000-102 High Temperature Kit (for actuators with 1-1/2 in.
stroke). Increases maximum temperature to 428°F (220°C).
Table 1. Close-off Ratings for ML6421, ML7421 Electric Linear Valve Actuators and Honeywell Valves (psi).
aFor use with ML6421B or ML7421B Actuators only.
bRepresents maximum pressure difference between the outlet and either of the two inlets.
cDo not exceed 100 psi with V5011G valves used in steam applications.
dRating is for steam at maximum 100 psi. Ratings for water applications are the same as for the V5011N1xxx.
Model
Stroke in
in. (mm)
Run Time in
sec at 60 Hz Description
ML6421A 3/4 (20) 95 Electric Linear
Valve Actuator
ML7421A
ML6421B 1-1/2 (38) 175
ML7421B
Type Valve 1/2 in. 3/4 in. 1 in. 1-1/4 in. 1-1/2 in. 2 in. 2-1/2 in. 3 in. 4 in.a5 in.a6 in.a
Flange V5011A,B,C — — — — — — 77 53 29 18 12
V5011B ———— — —— —
V3350/51/60/61;V3450/51/60/61 — — — — — — 63b45b25b16b11b
NPT V5011F,G 150c150c150c150c150c150c100 61 — — —
V5011N1xxx, V5011N3xxx,
V5013N
230 230 230 230 230 126 — —
V5011N2xxx 100d100d100d100d100d100d
V5013F 150 150 150 150 150 150

ML6421, ML7421 NON-SPRING RETURN ELECTRIC LINEAR VALVE ACTUATORS
3 63-2515—4
Fig. 1. Approximate dimensions of ML6421, ML7421 Electric Linear Valve Actuators in in. (mm).
INSTALLATION
When Installing this Product…
1. Read instructions carefully. Failure to follow them could
damage the product or cause a hazardous condition.
2. Check ratings and description given in the specifications
to make sure the product is suitable for your application.
3. Installer must be a trained, experienced service
technician.
4. After installation is complete, check out product
operation as provided in these instructions.
CAUTION
Electrical Shock or Equipment Damage Hazard.
Can shock individuals or short equipment
circuitry.
Disconnect power supply before installation.
Location
Install the actuator in a location that allows enough clearance
for mounting accessories and for servicing.
CAUTION
Equipment Damage Hazard.
Can damage actuator due to condensation or a
valve gland leak.
Install the actuator in a position above horizontal.
2-1/2
(64) 2-1/2
(64)
7 (178 ) X 7 (178) 7 (178 ) X 7 (178)
5-5/8
(142)
KNOCKOUTS
(2)
7/8 (22) 9-3/8
(239)
10-3/8
(264)
14-1/4
(360)
MINIMUM
CLEARANCE
8
(204)
11-7/8
(301)
12-3/4
(326)
16-7/8
(430)
MINIMUM
CLEARANCE
ML6421A,ML7421A ML6421B, ML7421B
M17430
YOKE DIAMETER 1-3/8 (35)
KNOCKOUTS
(2)
7/8 (22)
YOKE DIAMETER 1-7/8 (48)

ML6421, ML7421 NON-SPRING RETURN ELECTRIC LINEAR VALVE ACTUATORS
63-2515—4 4
Mounting
1. Place the actuator on the valve with the U-bolt around
the valve collar. See Fig. 2.
IMPORTANT
When tightening the set screws, first tighten the right
set screw. See Fig. 2.
2. Place the U-bolt against the valve collar and secure the
actuator to the valve by turning each U-bolt nut clock-
wise.
NOTE: To assure even pressure on the collar, first
tighten the nuts finger-tight and then alternate
turning each U-bolt nut until both are snug.
3. Push aside the stem button retaining clip and hold. See
Fig. 2.
4. Lift the valve stem until the head of the valve stem
button is inside the large slot of the stem button
retaining clip on the actuator.
5. Release the stem button retaining clip to secure the
stem button. Check to make certain the stem button is
secured by the retaining clip.
6. Pull off the manual operation knob.
7. Remove the cover from the actuator using a Phillips or
crosspoint screwdriver. See Fig. 3.
Fig. 2. Attaching actuator to valve.
Fig. 3. Removing actuator cover.
Wiring
CAUTION
Electrical Shock or Equipment Damage Hazard.
Can shock individuals or short equipment
circuitry.
Disconnect power supply before installation.
IMPORTANT
1. All wiring must comply with local electrical codes,
ordinances and regulations.
2. Voltage and frequency of the transformer used with
the actuator must correspond with the characteristics
of the power supply and those of the actuator.
NOTE: See Fig. 5 through 8 for typical wiring hookups.
1. Feed power and control wires through the conduit
connector located on the bottom of the actuator case.
CAUTION
Equipment Damage Hazard.
Conduit connection or removal can break an
unsupported connector.
When removing or attaching conduit, use a wrench to
support the motor connector.
2. Using the appropriate wiring diagram (see Fig. 5 through
8), connect power and control wires to the actuator.
Make sure that all wiring is correct.
3. For the ML7421 only: Check selector plugs for proper
settings. See Signal Input Failure section for details.
4. When wiring is complete, replace the actuator cover
and control knob (see Fig. 9).
5. Apply power and control signals to the actuator.
Fig. 4. Connecting wiring to the actuator.
M 17431
TIGHTEN RIGHT
SET SCREW FIRST
M17432
M6630

ML6421, ML7421 NON-SPRING RETURN ELECTRIC LINEAR VALVE ACTUATORS
5 63-2515—4
Fig. 5. ML6421 typical wiring diagram.
Fig. 6. ML7421 typical wiring diagram.
Fig. 7. ML7421 wiring using voltage input control and
separate transformers.
Fig. 8. ML7421 wiring using voltage input control and a
common transformer.
Fig. 9. Replacing actuator cover.
Auxiliary Potentiometers
The 43191679 Auxiliary Potentiometers can be used as feed-
back potentiometers and to provide remote indication of the
valve position. See the Accessories section for part numbers.
See Installation Instructions packed with the potentiometers
for details.
Auxiliary Switches
The 43191680 Dual Auxiliary Switch can be used on both the
ML6421 and ML7421 Electric Linear Valve Actuators.
Switching points are adjustable over the full actuator stroke.
For example, the switch can be used to switch pumps or to
provide remote indication of any stroke position. See the
Installation Instructions packed with the auxiliary switch for
details.
IMPORTANT
Use the 43191680 Dual Auxiliary Switch only with
24 Vac applications.
WIRING
STRIP
T1
T2
W
B
1
L1
(HOT)
L2
W
R
W
B
T
Y
G
R
BSPDT
ML6421A,B
2
3
POWER SUPPLY. PROVIDE DISCONNET MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
ALL WIRING BLOCKS HAVE THE SAME NUMBER
OF TERMINALS (8), BUT THE ONLY TERMINALS
THAT ARE ACTIVE ON THIS BLOCK ARE T1,W,AND B.
THE R-W-B AND T-Y-G TERMINALS ARE A SIX
TERMINAL WIRING BLOCK SEPARATE FROM THE
MAIN BLOCK. THEY DO NOT APPEAR ON ALL
MODELS BECAUSE R-W-B ARE FOR A SINGLE
FEEDBACK POTENTIOMETER AND T-Y-G ARE
FOR A SECOND FEEDBACK POTENTIOMETER
(BOTH POTENTIOMETERS ARE 220 OHMS). THE
REQUIRED WIRING BLOCKS ARE PART OF THE
POTENTIOMETER ACCESSORY KITS.
1
2
3
CONTROLLER
M17433
WIRING
STRIP
T1
+
T2
O1
O2
1
L1
L2
–
+
OUTPUT
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
0 TO 10 OR 2 TO 10 VDC CONTROL SIGNAL
(DEPENDING ON ACTUATOR MODEL).
1
2
M17434A
ML7421
L1
L2 1
1
1
1
2
2
3
3
456
L1
L2 1
T775 (WITH 2 TO 10 VDC OUTPUT)
DUAL
TRANSFORMERS
SENSOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED. M17435A
WIRING
STRIP
T1
+
T2
O1
O2
ML7421
L1
(HOT)
L2 1
1
1
1
2
2
3
3
456
T775 (WITH 2 TO 10 VDC OUTPUT)
SINGLE
TRANSFORMER
SENSOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED. M17436A
40 VA, 24 VAC
WIRING
STRIP
T1
+
T2
O1
O2
ML7421
M17464

ML6421, ML7421 NON-SPRING RETURN ELECTRIC LINEAR VALVE ACTUATORS
63-2515—4 6
OPERATION
General
The drive of the actuator synchronous motor is converted into
the linear motion of the actuator stem by using a worm gear
transmission. A button retainer clip connects the actuator
stem to the valve stem.
The internal force sensor, using installed microswitches, turns
off the actuator when the specified stem force is reached.
Manual Operation
The ML6421 and ML7421 are equipped with a manual
operator knob (see Fig. 10) to open or close the valve in the
event of power failure:
1. Turn off or disconnect the power supply before manually
operating the actuator.
2. Push down on the manual operator knob and turn the
knob:
a. Counterclockwise to drive the stem downward.
b. Clockwise to draw the stem upward.
IMPORTANT
Manual operation allows very high closing force that
can jam the actuator spindle, exceed the force switch
ratings, and stop the motor. After a manual valve
close-off operation, release the spindle one turn by
turning the manual operator knob. This will ensure
automatic disengagement of the manual operator
upon power resumption.
NOTE: If the manual operator knob is not pushed in while
turned, it will rotate only a short distance before
disengaging without power resumption.
Fig. 10. Manual operator knob.
ML7421
Signal Input Failure
Using selector plug W1, the actuator can be set to run to one
of three positions in event of a signal failure:
• 0%: Actuator position corresponds with 0 or 2 Vdc signal.
• 50%: Actuator stem in mid-position.
• 100%: Actuator position according to 10 Vdc signal.
NOTE: If W4 is set to the mA position, the actuator always
runs to 0 percent.
Output Signal Feedback (F)
An analog output signal (2 to 10 Vdc) that represents the
actual actuator stem position is available at Terminal F. It can
be used for remote indication of the stem position.
With the actuator stem fully down, the output signal is 10 Vdc.
The output of the signal does not change when the actuator
action reverses using W3 or W4 (see Signal Input Failure
section and Fig. 11).
Fig. 11. Location of selector plugs.
M6640
M17437
0-10V
(0-20mA)
2-10V
(4-20mA)
W2
10V (20mA) 0%
10V (20mA)
VmA
W4
W3 W1
100%50%

ML6421, ML7421 NON-SPRING RETURN ELECTRIC LINEAR VALVE ACTUATORS
7 63-2515—4
Actuator Override
To override the control signal (for freeze protection or similar
applications), connect the 24 Vac common (T2) to either
terminal O1 or O2. Connecting to terminal O1 fully extends
the actuator stem. Connecting to O2 fully retracts the actuator
stem.
The control signal (+) is ignored when the override signal is
applied to terminal O1 or O2. This override can be achieved
with a switch or a relay. See Fig. 12.
Direction of Action
The direction of action can be changed by repositioning the
selector plug W3.
Fig. 12. Connections for overriding control signal to drive
actuator to a specific position.
CHECKOUT
The actuator can be checked out either directly or using a controller.
Direct Checkout
1. Mount the actuator for the required application.
2. Check the valve position and make sure that 24 Vac is
correctly applied to the actuator.
3. Apply the control signal to the appropriate leadwires to
move the valve in the required direction.
4. If the actuator does not move, make sure the actuator is
properly installed.
5. If the actuator is correctly installed and does not run,
replace the actuator.
Controller Checkout
1. Adjust the setpoint of the controller to call for opening or
closing the valve. Observe the actuator.
2. If the valve is closed, it should begin to open.
3. If the valve remains closed, move the setpoint further
toward the open setting.
4. If the valve does not move, check for 24 Vac in the
actuator power input.
5. If 24 Vac is present and the actuator does not operate,
reverse the controller leadwires to determine if the
device is incorrectly wired.
6. If wiring is correct, 24 Vac is present on the power input
terminals, and the actuator does not run, replace the
actuator.
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
F
+
0-10Vdc OR 2-10 Vdc CONTROL SIGNAL. SEE SIGNAL
INPUT (+) SECTION.
SEE OVERRIDE SECTION FOR DETAILS ON
OVERRIDE OPERATION.
2-10 Vdc FEEDBACK SIGNAL. SEE OUTPUT SIGNAL
FEEDBACK SECTION.
ML7421
WIRING
STRIP
F
+
–
T2
T1
O1
O2
1
3
4
2
INPUT
(FEEDBACK)
OUTPUT
3
2
SP3T
OVERRIDE
SWITCH
41
L1
(HOT)
L2
–
M17438

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