DC bus overvoltage

What does ObF mean?

This fault indicates that the DC bus voltage within the drive has exceeded its safe operating limits, often referred to as "overbraking." This usually happens when the motor regenerates energy back into the drive during deceleration, and there's no braking resistor to dissipate it.

• Motor decelerating too rapidly, regenerating energy into the DC bus.
• Lack of or insufficient braking resistance to dissipate regenerated energy.
• Excessive line voltage, contributing to a high DC bus voltage.

Click steps to track your progress.

1. 1

   Increase the deceleration ramp time ([Deceleration] (dEC) or [Deceleration 2] (dE2)) to reduce regenerative energy.

2. 2

   Install or verify the sizing and connection of a dynamic braking resistor.

3. 3

   Ensure the braking unit, if present, is functioning correctly.