Overvoltage (Steady State/Acceleration)

What does OSF mean?

This fault occurs when the DC bus voltage within the drive controller is too high, either during steady-state operation or acceleration, usually caused by an excessively high incoming line voltage. High DC bus voltage can stress and damage the drive's internal capacitors and power semiconductors.

• Incoming AC line voltage consistently above the drive's maximum rated input voltage (e.g., 480V input for a 400V drive).
• Voltage transients or spikes on the incoming AC power supply during acceleration.
• Incorrectly tapped input transformer providing excessively high voltage to the drive.
• Drive DC bus capacitance degradation, reducing its ability to absorb voltage fluctuations.
• Excessively short acceleration ramp time (Parameter P0-11) causing rapid voltage changes.

Click steps to track your progress.

1. 1

   1. Measure incoming AC line voltage (L1-L2, L2-L3, L3-L1 terminals) with a true RMS multimeter and compare to drive's rated input voltage.

2. 2

   2. Verify acceleration ramp time (Parameter P0-11) is not excessively short, which can cause voltage spikes.

3. 3

   3. Check input transformer taps if applicable and adjust to lower output voltage (if within acceptable range).

4. 4

   4. Monitor DC bus voltage (drive display parameter P0-08 or similar) during operation to observe peak voltage.

5. 5

   5. Consider installing an AC line reactor or surge protector to mitigate line voltage spikes.