Cause : Braking chopper overcurrent comes when an overcurrent condition has occurred in the braking chopper. When encountering a braking chopper overcurrent fault in a Siemens SINAMICS G120 drive, it indicates that the current flowing through the braking chopper has exceeded its rated capacity.

This typically occurs during regenerative braking when excess energy from the motor is fed back into the drive and needs to be dissipated by the braking chopper.

1. check whether the braking resistor has a short circuit.
2. for an external braking resistor, check whether the resistor may have been dimensioned too small.

Here's how you can address this issue:

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

2. Identify the Cause: Determine the reason for the braking chopper overcurrent fault. Common causes include:

   • Excessive regenerative energy generated during deceleration or braking.
   • Incorrect configuration settings or parameterization of the braking chopper.
   • Faulty braking resistor or its connection.
   • Overloading of the drive beyond its rated capacity.

3. Inspect Braking Resistor: Check the braking resistor and its connection to the drive. Ensure that the resistor is properly sized and rated for the application. Inspect the wiring and connections for any signs of damage, overheating, or loose connections.

4. Adjust Braking Chopper Settings: Review the parameterization and configuration settings of the braking chopper in the SINAMICS G120 drive. Verify that the settings are appropriate for the application and adjust parameters related to braking chopper operation, such as current limits and duty cycle, if necessary.

5. Monitor Regenerative Energy: Utilize diagnostic tools provided by the drive to monitor the regenerative energy generated during deceleration or braking. Analyze the energy levels and trends to identify any excessive regenerative energy that could lead to overcurrent faults.

6. Implement Additional Braking Resistors: If the braking chopper is unable to handle the regenerative energy, consider adding additional braking resistors or increasing the capacity of the existing resistor to dissipate excess energy effectively.

7. Inspect Motor Parameters: Verify the motor parameters configured in the SINAMICS G120 drive. Ensure that the motor parameters, such as rated torque and speed, are set correctly according to the specifications of the connected motor.