What would cause the InF fault on the ATS48 softstarter?


16 June 2022

InF fault causes on the ATS48 softstarter.

Product line:  
Altistart 48, ATS48

All models, all serial number

InF displayed on the unit. 

InF is an Internal fault. Try disconnecting the Control Voltage from CL1,CL2 terminals to see if the fault will reset.
This fault appears if the control board cannot determine the soft starts power rating from the information stored in the EEPROM memory chip on the power board. 

Possible causes are:
- Loose ribbon cable connection on the Power board or the Control Board.  Try remove the control board, check the plugs and pins. Reseat the control board back in place.
   A few cases were observed in the field where the ribbon connector got loose due to vibration and caused this InF fault. The ribbon cable has to be reseated to fix the problem.

- The 24VDC is saturated.  Remove all connections to +24 terminal and then measure the voltage.

- SCR is shorted. Check Resistance across each SCR.

- If another ATS48 unit is available, try swapping control boards to confirm if the issue stays with the board or the soft start. 

- Power rating not recognized.  Replace the Power board and/or Control board.