OU2 fault in INVT GD10 indicates Over voltage when deceleration. This means that the drive internal main circuit DC voltage has reached or exceeded the specified value during deceleration.

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

• Deceleration time too short: The drive may not have enough time to dissipate the energy stored in the DC bus capacitors during deceleration.
• Large load inertia: A large load inertia can cause the motor to continue rotating for a longer period of time after the deceleration command is issued, leading to overvoltage.
• Inverter power rating too small: The inverter may not be able to handle the high current demands during deceleration, leading to overvoltage.
• Faulty components: Faulty components in the drive, such as the DC bus capacitors or the IGBT modules, can also lead to overvoltage.

To troubleshoot the OU2 fault, you can try the following steps:

1. Check the deceleration time setting: Ensure that the deceleration time is set to an appropriate value. A longer deceleration time will allow the drive to dissipate the energy stored in the DC bus capacitors more slowly, reducing the risk of overvoltage.
2. Check the load inertia: If the load inertia is large, you may need to increase the deceleration time or reduce the motor speed.
3. Check the inverter power rating: Make sure that the inverter is rated for the appropriate power level. If the inverter is undersized, it may not be able to handle the high current demands during deceleration.
4. Check for faulty components: If the above steps do not resolve the issue, you may need to check for faulty components in the drive, such as the DC bus capacitors or the IGBT modules.