OU3 fault in INVT GD10 indicates Over voltage when constant speed running. This means that the drive internal main circuit DC voltage has reached or exceeded the specified value during constant speed operation.

This can be caused by a variety of factors, including:

• No braking components: If the motor is not equipped with a braking resistor or other braking device, the energy generated during deceleration cannot be dissipated, leading to overvoltage.
• Braking energy not dissipated: The braking resistor or other braking device may not be able to dissipate the energy generated during deceleration, leading to overvoltage.
• Power supply abnormal: A surge voltage in the power supply system can also trigger the OU3 fault.

To troubleshoot the OU3 fault, you can try the following steps:

1. Check for braking components: Ensure that the motor is equipped with a braking resistor or other braking device. If not, install one.
2. Check the braking resistor: If the motor is equipped with a braking resistor, check its resistance value and ensure that it is properly connected.
3. Check the power supply: Make sure that the power supply is stable and free of surges.
4. Check the drive settings: Ensure that the drive settings, such as the deceleration time and braking resistance value, are correct.