Why doesn’t frequency value change when adjusting potentiometer in a VFD?

There are two possible cases:

Case 1: The frequency value does not change, but motor speed changes when adjusting potentiometer. The reason for this is that VFD is in a display mode showing a different parameter, such as DC bus voltage, output voltage, output current, etc. To adjust VFD to display frequency value, press the SHIFT key multiple times until LED displays Hz.

Case 2: Neither the frequency value nor motor speed changes when adjusting potentiometer. The possible reasons for this are:

  • Incorrect speed reference source setting
  • Incorrect potentiometer wiring
  • The potentiometer wiring is damaged or connection to control terminal is poor
  • The potentiometer value is inappropriate or potentiometer is faulty
  • The VFD has reached its current limit due to overload

You should:

  • Set speed reference source parameters correctly for your specific VFD model
  • Ensure that potentiometer is wired accurately according to provided instructions
  • Check potentiometer wiring for any breaks and tighten control terminal connections for good contact
  • Use a suitable potentiometer with correct value and ensure it is not damaged
  • Contact your VFD supplier for further assistance.