DC Bus Overvoltage

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The DC bus voltage inside the drive has exceeded its safe operating limit. This is most commonly caused by regenerative energy from the motor, particularly during rapid deceleration of high-inertia loads, or by an excessively high incoming line voltage. Unresolved overvoltage can lead to damage to the drive's internal power components.

• Rapid deceleration of a high-inertia load without an adequately sized braking resistor or braking unit.
• Input line voltage (e.g., L1-L2, L2-L3, L3-L1) exceeding the drive's maximum rated voltage during operation.
• Motor cable capacitance (especially with long cables) causing voltage spikes during IGBT switching.
• Faulty internal DC bus voltage measurement circuit providing an incorrect reading.
• Incorrectly set acceleration/deceleration ramps (e.g., P1-03, P1-04) that are too short for the connected load.

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1. 1

   1. Measure the input line voltage (e.g., L1-L2, L2-L3, L3-L1) to ensure it is within the drive's specified limits.

2. 2

   2. Increase the deceleration ramp time (e.g., Parameter P1-04) to reduce regenerative energy during stops.

3. 3

   3. Verify the braking resistor (if installed) is correctly sized (e.g., Ohm value, Wattage) and wired to the drive's terminals (e.g., BR+ to BR-).

4. 4

   4. Check the resistance of the braking resistor; verify it is not open-circuit or short-circuit.

5. 5

   5. Inspect the motor cable for proper shielding and ensure its total length is within the drive's specifications.

6. 6

   6. Monitor the DC bus voltage (e.g., via HMI or serial communication) during operation to pinpoint the exact overvoltage event.