Overvoltage

What does -OSF mean?

This fault indicates that the DC bus voltage within the drive controller has exceeded a safe threshold during steady-state operation or acceleration. The primary cause is typically an input line voltage that is consistently higher than the drive controller's nominal rating, which can stress and damage internal power components like the DC bus capacitors and IGBTs.

• Input line voltage (L1, L2, L3) consistently exceeding the drive's maximum allowable input voltage (e.g., >480V for a 400V drive).
• Regenerative energy from the motor (e.g., during rapid deceleration or with an overhauling load) without a braking resistor or sufficient deceleration time.
• Malfunctioning dynamic braking resistor or braking chopper circuit, unable to dissipate regenerated energy.
• Input voltage imbalance across phases exceeding acceptable limits (e.g., >2%), causing peak voltage spikes on the DC bus.
• Drive internal DC bus voltage measurement circuit fault, providing an inaccurate overvoltage reading.

Click steps to track your progress.

1. 1

   Measure the input line voltage (L1-L2, L2-L3, L3-L1) at the drive input terminals (R, S, T) using a multimeter.

2. 2

   Verify deceleration ramp time (Parameter P1-04) is sufficient for the load inertia; increase by 1-2 seconds if deceleration is too fast.

3. 3

   If using a braking resistor, measure its resistance with a multimeter and check connections to drive terminals (+DC, BR).

4. 4

   Check input voltage imbalance across phases (L1-L2, L2-L3, L3-L1). Imbalance greater than 2% can cause issues.

5. 5

   Consider installing an input line reactor to smooth out input voltage transients and mitigate voltage peaks if supply quality is poor.