Cause : DC link overvoltage comes when the power unit has detected overvoltage in the DC link on a pulse inhibit. When you encounter a DC link overvoltage fault in a Siemens SINAMICS G120 drive, it indicates that the voltage level in the DC link has exceeded the permissible limit.

This can happen due to various reasons, including regenerative energy from the motor during deceleration, disturbances in the power supply, or issues with the braking resistor.

- device connection voltage too high.
- line reactor incorrectly dimensioned.

1. check the device supply voltage (p0210).
2. check the dimensioning of the line reactor.
3. See also: p0210 (Drive unit line supply voltage)

Here's how you can address this issue:

1. Stop Operation: Immediately stop the operation of the drive to prevent any further damage to the equipment and ensure safety.

2. Identify the Cause: Determine the reason for the DC link overvoltage fault. Common causes include:

   • Regenerative energy from the motor during deceleration or braking.
   • Power supply fluctuations or disturbances.
   • Issues with the braking resistor or its connection.
   • Incorrect configuration settings or parameterization of the drive.

3. Inspect Braking System: Check the braking resistor and its connection to the drive. Ensure that the resistor is functioning correctly and that its capacity matches the requirements of the application. Inspect the wiring and connections for any signs of damage, overheating, or loose connections.

4. Review Drive Parameters: Verify the parameterization and configuration settings of the SINAMICS G120 drive. Pay particular attention to parameters related to braking and regenerative energy handling. Adjust these parameters as necessary to optimize the performance and prevent overvoltage conditions.

5. Monitor DC Link Voltage: Utilize diagnostic tools provided by the drive to monitor the DC link voltage during operation. Analyze the voltage waveform and trends to identify any irregularities or spikes that could indicate an overvoltage condition.

6. Implement Protective Measures: Consider implementing additional protective measures such as dynamic braking modules, external braking resistors, or voltage clamping devices to mitigate the risk of DC link overvoltage faults.