Regenerative Overvoltage during Acceleration

What does E.OV1 mean?

Regenerative power or a power supply surge has caused the inverter's internal main circuit DC voltage to rise above the specified limit, triggering the protective shutdown. This can occur with rapid acceleration, especially with vertical loads, or if stall prevention settings are incorrect. Continued overvoltage can damage inverter components.

• External mechanical load actively driving the motor faster than the commanded speed during acceleration, causing regenerative energy feedback.
• Unstable or excessively high incoming AC line voltage (e.g., > 480VAC for 400V class inverters) leading to an elevated DC bus voltage.
• Failure of the braking transistor or internal braking circuit components, preventing dissipation of regenerative energy.
• Incorrectly sized or faulty external braking resistor (e.g., too high resistance, open circuit) resulting in inadequate energy dissipation.

Click steps to track your progress.

1. 1

   1. Measure incoming AC line voltage at the inverter L1, L2, L3 terminals under load to verify it remains within +/-10% of the rated input voltage.

2. 2

   2. If an external braking resistor is used, measure its resistance to ensure it matches the specified value (e.g., +/-5%) and is not an open circuit.

3. 3

   3. Verify braking transistor operation by monitoring DC bus voltage during commanded acceleration, observing if the voltage stabilizes.

4. 4

   4. Increase Pr.7 (Deceleration time) by 20-50% if the fault typically occurs after a previous rapid deceleration, to allow DC bus to settle.

5. 5

   5. Evaluate the mechanical system by disconnecting the motor to determine if the load can drive itself (e.g., an overhauling load).