background image

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

Summary of Contents for ML6421

Page 1: ...tput 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 consum...

Page 2: ...nge 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 A...

Page 3: ...uct 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 ...

Page 4: ...emoving 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 th...

Page 5: ...ons WIRING STRIP T1 T2 W B 1 L1 HOT L2 W R W B T Y G R B SPDT 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 BECAU...

Page 6: ...ase 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...

Page 7: ...e 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 re...

Page 8: ...al Honeywell Europe S A Honeywell Latin American Honeywell Honeywell Limited Honeywell Limitée Control Products 3 Avenue du Bourget Region 1985 Douglas Drive North 35 Dynamic Drive Honeywell Building 1140 Brussels 480 Sawgrass Corporate Parkway Golden Valley MN 55422 Scarborough Ontario 17 Changi Business Park Central 1 Belgium Suite 200 M1V 4Z9 Singapore 486073 Sunrise FL 33325 ...

Reviews: