Why does the ATV61 or ATV71 AC drive display motor short circuit or IGBT short circuit fault codes when powered by a generator?


28 September 2021

ATV61/ATV71 drives displays IGBT short circuit fault codes when powered by a generator.

Product Line:
Altivar ATV61 and ATV71

All ATV61 and ATV71's when powered with a generator

These are not true short circuit faults but are occurring as a result of power supply instability and high voltage during the transient state of initial generator power.

Investigate and correct the instability and over voltage conditions during transient state of initial generator power.

Troubleshooting tips:
·         The drive does not have a run command when these fault codes occur.
·         In some cases during the open transition the drive will display [Mains Overvoltage] (OSF) or [Overbraking] (ObF) rather than an SCF fault code.
·         In all cases where an SCF fault code occurs it is preceded in the fault detection history by a [Mains Overvoltage] or [Overbraking] fault code.
·         When the SCF fault codes occurs the drive state indicated in the fault detection history on the graphic display is FLT. Normally an SCF will not occur when the drive is in FLT state.
Potential Work Arounds:
1.       With a normally open timed to close contact, open the drive's +24V supply to the PWR input for 30 seconds on initial power up. The drive will now display a PRA state indicating the PWR input is opened. This will prevent an SCF fault code from occurring during the 30 second period. After the 30 second time delay the drive will go to RDY ready state and can be commanded to run.
2.       A logic input can be assigned to the [Product Reset Assign] parameter found in the [Fault Management ] menu. This will now allow an SCF fault code to be reset remotely without having to power cycle the drive.  As a caution, before resetting an SCF with this function, be sure there is not a true short circuit present that could cause equipment damage. Reference the ATV61/ATV71 programming manual for this function.
3.       Do not apply power to the drive until after the generator power has stabilized.