Honeywell ML6421 User 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

Honeywell ML6421 Specifications

General

Brand	Honeywell
Model	ML6421
Category	Controller
Language	English

Summary

Product Overview and Features

Key Features

Highlights actuator capabilities, ease of installation, and performance characteristics.

Application Scope

Defines actuator suitability for HVAC systems and controller compatibility.

Product Specifications

Model and Stroke Details

Lists actuator models ML6421A/B, ML7421A/B and their stroke lengths.

Electrical and Signal Characteristics

Covers electrical ratings, power consumption, and signal input types.

Pressure Ratings, Approvals, and Protection

Details pressure ratings, certifications, and IP protection standard.

Installation and Mounting

Location Considerations

Guidance on selecting an appropriate installation location for the actuator.

Mounting Procedures

Step-by-step instructions for physically attaching the actuator to the valve.

Wiring and Electrical Connections

Wiring Diagrams and Best Practices

Visual connection guides and best practices for actuator wiring.

Auxiliary Component Integration

Info on integrating auxiliary potentiometers and switches for enhanced functionality.

Operation and Control Signals

Manual Operation and General Function

How to operate the actuator manually and general drive mechanisms.

Signal Input Failure and Output Feedback

Configuration for signal loss and explanation of output feedback signals.

Advanced Control and Verification

Actuator Override and Direction Control

How to override control signals and change the actuator's direction of action.

Checkout and Troubleshooting

Procedures for verifying actuator function and basic troubleshooting steps.