DC Bus Overvoltage (Braking/Earth Leakage)

What does OUE mean?

An overvoltage condition has occurred, specifically related to braking operations or an earth leakage at the motor end. During braking, insufficient deceleration time or an undersized/defective brake resistor can cause this. An earth leakage in the motor or cable also contributes. This fault indicates high stress on the drive's DC bus, potentially leading to component failure.

• Insufficient deceleration time (P0-11, P0-12) causing excessive regenerative energy from the motor during braking.
• Undersized or defective brake resistor (P6-30, P6-31) unable to dissipate regenerative energy effectively.
• Faulty brake chopper circuit within the drive, preventing the brake resistor from engaging or dissipating power.
• Earth leakage fault on the motor cable or within the motor windings, causing current imbalance and voltage fluctuations.
• High incoming mains voltage combined with regenerative braking effects, pushing the DC bus over the limit.

Click steps to track your progress.

1. 1

   Increase the deceleration ramps (P0-11 for ramp 1, P0-12 for ramp 2) to allow for slower and more controlled motor stops.

2. 2

   Verify the specified resistance (P6-30) and power rating (P6-31) of the brake resistor against actual application needs and drive limits.

3. 3

   Check the brake chopper function by monitoring the brake resistor current or voltage during deceleration with a clamp meter/oscilloscope.

4. 4

   Perform an insulation resistance test on the motor and motor cable to ground using a megohmmeter (e.g., 500VDC test voltage).

5. 5

   Measure the incoming mains voltage (L1, L2, L3) and ensure it is stable and within the drive's permissible input voltage range.