Troubleshooting actuator potentiometer feedback wiring

The feedback potentiometer wiring must be properly connected to the control. Determining the correct wiring can be difficult on some actuators or potentiometers. Common symptoms of incorrect feedback wiring or potentiometer issues include:

• The actuator osciillates back and forth
• The actuator not travelling the full stroke during calibration

Potentiometers have three wires: positive (+), negative (–), and feedback (FB). If the feedback wire is not connected to the FB terminal on the control, the actuator will not function properly. Because the wires are often different colours and are not always labelled the same as above, measuring the resistance between the wires is the best way to determine which wire is the feedback wire. Follow the steps below to measure the resistance and determine the correct wiring.

NOTES:
Before checking the potentiometer wires, verify that the power wires are properly connected.
Test the actuator using the control's manual or test mode.

Procedure

1. Manually move the actuator away from the end of its stroke by at least a quarter of its total stroke.
2. Disconnect all three potentiometer wires from the control.
3. Number the wires 1, 2, and 3, in any order.
4. Set your ohmmeter to measure the potentiometer's maximum resistance, normally 20,000 Ω.
5. Measure and record the resistance between wires 1 and 2. _________ Ω
6. Measure and record the resistance between wires 1 and 3. _________ Ω
7. Measure and record the resistance between wires 2 and 3. _________ Ω
8. The pair of wires with the highest measured value are the positive and negative wires. Connect the wires to the positive and negative actuator terminals on the control. At this time, do not be concerned with which wire you connect to which terminal.
9. Connect the remaining wire to the feedback terminal.
10. Test the actuator using the control's automatic mode to see if it moves properly. If the actuator moves in the opposite direction than it is supposed to, switch the positive and negative wires on the control.