20 July 2022
OLF on the ATV12/ATV312/ATV32/ATV320/ATV61/ATV71 Drives.
Altivar ATV12 ATV312, ATV32, ATV320, ATV61 and ATV71 Drives
Motor is pulling too much current
Motor overload fault (OLF) is triggered by the motor pulling current above the ItH (Motor Them Current) that is programmed into the drive. The further the current is above the ItH setting, the less time it will take to trip on OLF. Note that there is a 10% service factor built into the trip curve.
Check motor load. Check motor nameplate settings in the drive such as the
bFR : standard motor frequency
unS : Rated Motor Voltage
nCr : Rated Motor Current
nSP : Rated motor RPM
Also check current limitation settings. Verify the motor current is balanced in all three legs, and not exceeding the motor FLA. Check that the motor thermal current setting (ITH) is programmed according to motor name plate.
Note that by default the ATV12 drive does not store the thermal state of the motor when power is removed from the drive, so this fault could be reset by a power cycle without waiting for the motor to cool.
It is recommended to change the Motor thermal state memo from NO to YES. This means the OLF fault cannot be cleared by a power cycle. Instead power needs to remain on the drive until the calculated thermal state of the motor has dropped to an acceptable level.
The Motor thermal state is displayed in the Monitoring menu, parameter tHr. The drive will trip when the tHr parameter reaches 118%. It will not allow a reset until the tHr drops below 100%.