Cause : Overvoltage comes when voltage in the DC bus has exceeded the overvoltage detection level. When a Yaskawa drive indicates an "Overvoltage" fault, it means that the voltage supplied to the drive exceeds the specified limit.

A DC bus overvoltage fault in your Yaskawa drive indicates that the voltage in the internal DC bus has exceeded the safe operating limit. This can cause damage to the drive components and prevent the motor from functioning properly. Here's a breakdown of the DC bus overvoltage fault in Yaskawa drives, its causes, and troubleshooting steps:

Possible Causes:

• Input Voltage Issues:

• High Input Voltage: The AC line voltage supplying the drive might be exceeding the acceptable range for your specific Yaskawa drive model.
• Power Spikes or Surges: Voltage spikes or surges on the AC input line can momentarily raise the DC bus voltage above the limit.

• Drive Regeneration: In applications where the motor acts as a generator by feeding energy back to the drive (regenerative braking), the DC bus voltage can increase if the drive lacks sufficient capacity to absorb this energy.
• Motor Faults: A defective motor with internal issues like shorted windings can lead to regeneration and contribute to a DC bus overvoltage fault.
• Incorrect Drive Settings: Inappropriate settings for parameters like speed search or deceleration time might not handle motor regeneration effectively, causing overvoltage.

Troubleshooting Steps:

1. Safety First: Ensure the system is completely powered down and locked out before attempting any troubleshooting procedures.
2. Verify Input Voltage:

• Check Voltage Rating: Consult the Yaskawa drive manual for your specific model to confirm the acceptable AC input voltage range.
• Measure Input Voltage: Use a voltmeter to measure the AC line voltage supplying the drive. If it's consistently exceeding the acceptable range, consider contacting your power supplier or implementing voltage regulation equipment.

3. Analyze Motor Operation- Regenerative Braking: If your application involves regenerative braking, ensure the Yaskawa drive is sized appropriately to handle the regenerated energy without exceeding the DC bus voltage limit. You might need to adjust motor control parameters or consider adding a regenerative braking resistor.
4. Check Motor Condition: Although less common, rule out potential motor faults by ensuring the motor is healthy and operating within its specifications. Refer to the motor's manual for troubleshooting steps specific to motor faults.