Honeywell ml7421 Benutzerhandbuch

7

63-2515—4

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.

The direction of action can be changed by repositioning the 
selector plug W3.

The actuator can be checked out either directly or using a controller.

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.

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

4

1

L1 
(HOT)

L2

–

M17438