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Limitorque MX/QX Series Electric Actuators: Terminal Wiring & Commissioning

source： date：2026-09-29

The Limitorque MX series from Flowserve (USA) uses the Modutronic electronic control unit; the QX series is the part-turn (quarter-turn) version with essentially the same commissioning method. Based on the MX commissioning manual, this article covers on-off and modulating terminal wiring and the complete commissioning procedure.

On-Off Type Terminal Wiring

Terminal	Function	Description
L1、L2、L3	Three-phase supply	380V three-phase; mind the phase sequence
PE	Earth	Protective earth terminal
22、25	Open command	Valve open command, remote via dry contact
22、27	Close command	Valve close command, remote via dry contact
46、47	Valve fully open	Open feedback signal
44、45	Valve fully closed	Closed feedback signal

Wiring note: jumper terminals 21 and 28 (internal 24V supply).

Modulating Type Terminal Wiring

Terminal	Function	Description
L1、L2、L3	Three-phase supply	380V three-phase; mind the phase sequence
PE	Earth	Protective earth terminal
20(+)、19(-)	Analog control command	Analog command 4–20 mA
18(+)、17(-)	Analog feedback	Analog feedback 4–20 mA

Commissioning Procedure

Step 1: Preparation

Wiring complete, guards restored, actuator energized

Step 2: Enter setup

Turn the red knob to "STOP", then within 10 s operate the black control knob quickly: YES → NO → YES until the LCD shows "SETUP"
YES → YES → YES; enter password 100 (first digit: toggle NO to 1, then four YES presses)

Step 3: Setup menu

The main menu contains:

VALVE SETUP
TORQUE SETUP
CHANGE POSITION SETUP
CHANGE LOCAL CONTROL
CHANGE MODUTRONIC (analog control settings)
INITIALIZE

Step 4: Limit setting (close first, then open)

Select CHANGE POSITION SETUP → SET CLOSE POSITION LIMIT
Turn the red knob to LOCAL and run the actuator to fully closed
Confirm CLOSE VALVE OK? → YES
Save: SAVE CLOSE LIMIT OK? → YES
Select SET OPEN POSITION LIMIT and set the open limit the same way
Set closing direction: CLOSE DIRECTION (CW) → confirm clockwise or counter-clockwise

Note: normally both directions are set to POSITION. The close direction may be set to TORQUE if needed, but the open direction must never be torque seated.

Step 5: Torque setting

Select the TORQUE SETUP menu
Set OPEN TORQUE and CLOSE TORQUE
Factory values are typically 40%–41%; turning the black knob to "NO" increases the percentage
Keep open and close torque values consistent

Note: torque is factory-set to the valve's maximum; normally no change is needed. Over-setting can damage the valve stem or internal worm gearing.

Step 6: Finish

Turn the red knob directly to LOCAL or REMOTE