What causes the InF fault on an ATS48 soft starter?

The InF fault indicates an internal fault in the ATS48 soft starter.

This fault typically occurs when the control board cannot detect the soft starter’s power rating stored in the EEPROM memory on the power board.

Initial reset step:

• Disconnect the control voltage from terminals CL1 and CL2, then reapply power to check if the fault clears.

If the fault persists, possible causes include:

• Loose ribbon cable connection between the control board and power board.
  • Remove the control board, inspect the connectors and pins, and reseat the ribbon cable.
  • In some installations, vibration can loosen this connection and trigger the InF fault.

• 24 VDC supply saturation.
  • Disconnect all wiring from the +24 V terminal and measure the output voltage.

• Shorted SCR.
  • Measure resistance across each SCR to verify proper operation.

• Faulty control or power board.
  • If available, swap control boards with another ATS48 unit to determine whether the issue follows the board or remains with the soft starter.

• Unrecognized power rating.
  • Replace the power board and/or control board as required.

If this article does not answer your question, check out our FAQ database that has answers to more commonly asked questions:

Frequently Asked Questions - Schneider Electric (se.com)

If this FAQ did not solve your issue, you can call us at 1-888-778-2733 Option 2 and then 4 or e-mail us atdrive.products.support@se.comto create a case with our Technical Support Team.

If you are not located in North America, please contact your local Customer Care Center for assistance:

Support | Schneider Electric Global (se.com)