Honeywell ML7425A, ML7420A SPECIFICATION DATA

ML7420 ML7425

GENERAL

The ML7420A / ML7425A,B actuators are designed for modulating control with controllers providing an analog output of 0...10 Vdc or 2...10 Vdc. They operate Honeywell’s standard valves in heating, district heating, ventilation, and air conditioning (HVAC) applications. Spring-return models provide a safety position at power failure.

ML7420A/ML7425A,B

Electric Linear Valve Actuator

SPECIFICATION DATA

FEATURES

• Easy and quick installation

• No separate linkage required

• No adjustments required

• Low power consumption

• Force-limiting end stops

• Spring-return models (ML7425A,B)

• Manual operation knob

• Position feedback signal

• 0...10 Vdc or 2...10 Vdc signal input selectable

• Direct / reverse action selectable

• Stroke position on signal failure selectable

• Corrosion-resistant design

• Maintenance-free

SPECIFICATIONS

Temperature Limits

Ambient operating limits -10...+50 °C Ambient storage limits -40...+70 °C at 5...95% r.h. Medium valve

temperature Max. 150 °C (220 °C with

High-Temperature kit)

Signals

Signal input voltage y =

Signal source 1 kΩ max. Position feedback signal x = 2...10 Vdc Load 1 mA max.

Safety

Protection class III as per EN60730-1 Protection standard IP54 as per EN60529 Flame retardant housing V0 as per UL94

(with metal cable gland)

0...10 Vdc or 2...10 Vdc

= 100kΩ

at 5...95% r.h.

ML7420A/ML7425A,B

Wiring

Wiring terminals 1.5 mm Cable entry M20. Two additional knock-

outs M18 and M20 for auxiliary switch and potentiometer accessories

model number ML7420A6009 ML7420A6017 ML7425A6008 ML7425B6007

supply voltage 24 Vac ±15%; 50/60 Hz

power consumption

signal input 0(2) Vdc Actuator stem retracted. Two-way valve:”open”, three-way valve port A-AB:”closed” *

signal input 10 Vdc Actuator stem extended. Two-way valve:”closed”, three-way valve port A-AB:”open” *

stroke 20 mm

run time at 50 Hz 1 min 0.5 min 1.8 min

close-off force ≥ 600 N

spring return time ⎯ ≈12 s

spring return direction

* Factory setting; can be reversed by pressing the right-hand pushbutton (W3) located on the PCB (see Fig. 1).

5 VA 7 VA 12 VA

⎯

Weight

non-spring return type 1.3 kg spring return type 2.4 kg

Material

Cover ABS-FR Base glass fiber reinforced plastic Yoke aluminum diecast

actuator stem extends

at power failure

actuator stem retracts

at power failure

OPERATION

General

The drive of a synchronous motor is converted into linear motion of the actuator stem via a spur gear transmission. The actuator stem is connected with the valve stem by a buttonkeyed retainer connection.

An integrated spring package limits the stem force to a factory-set value in either direction.

The actuator switches off precisely when the specified stem force is reached.

Manual Operation

Actuators without spring return are equipped with a manual operation knob used in case of power failure. Manual operation is permitted only after the power supply is switched off or disconnected.

To operate, push the manual operation knob down and turn clockwise to move the stem downward and counterclockwise to move the stem upward. If the actuator returns to automatic control, the manual operation knob unlocks automatically.

In the case of actuators with spring return, the manual operation knob is located under the cover.

Override Option

All actuators have an integrated override function (see also Fig. 3). When the override signal is applied, the actuator drives to the fully-open or fully-closed position, regardless of the controller signal.

Spring Return

The ML7425A,B spring return actuators provide a defined safety position of the valve in case of power failure.

The spring return actuators are shipped from the factory with a shipment stop (to lock the manual operation knob) in order to allow connection of the stem button retainer to the valve stem without power supply.

Electrical Installation

The actuators are delivered with a pre-installed cable gland M20 and two additional knock-outs for M18 and M20. Max. cable length/diameter for field mounting:

200 m / 1.5 mm 100 m / 1.5 mm2 (ML7420A6017)

NOTE: To avoid malfunction, it is necessary to connect

24 Vac power and ground (see Fig. 3 on page 4).

Action

The direction of action can be reversed by pressing the lefthand pushbutton (W3) located on the printed circuit board (see Fig. 1), If the corresponding LED is lit, this indicates that the actuator stem will retract at a control signal of 0(2) Vdc (factory setting); if it is dark, the actuator stem will extend at a control signal of 0(2) Vdc.

Input Signal Range

The range of the analog input signal Y can be changed by pressing the right-hand pushbutton (W2) located on the printed circuit board (see Fig. 1). If the corresponding LED is lit, this indicates that the actuator is set for 0...10 V operation (factory setting); if it is dark, the actuator is set for 2...10 V operation.

EN0B-0261GE51 R0707 2

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