Overvoltage During Deceleration

What does -ObF mean?

This fault occurs when the motor generates excessive regenerative energy back into the drive controller's DC bus during rapid deceleration or when driving an overhauling load (e.g., lowering a weight). This rapid increase in DC bus voltage can exceed safe limits and damage the drive's internal components if not dissipated properly.

• Deceleration ramp time (Parameter P1-04) set too short for the inertia of the driven load, causing rapid energy regeneration.
• Overhauling load application (e.g., crane, elevator, high-inertia fan) generating significant regenerative energy back into the DC bus.
• Braking resistor circuit malfunction (e.g., open resistor, failed braking chopper module), preventing energy dissipation.
• Drive's internal DC bus capacitors reaching end-of-life, reducing their capacity to absorb regenerative energy and causing voltage spikes.
• Incorrect overvoltage trip level (Parameter P5-02) set too low, causing premature tripping during normal deceleration.

Click steps to track your progress.

1. 1

   Increase the deceleration ramp time (Parameter P1-04) by 1-2 seconds and retest the application.

2. 2

   Measure the resistance of the external braking resistor with a multimeter (power OFF). Compare to its specified value.

3. 3

   Verify the braking chopper is functioning by measuring voltage across the braking resistor during deceleration (if safely possible).

4. 4

   If an overhauling load is present, confirm the braking resistor and chopper are correctly sized for the application's regenerative energy.

5. 5

   Ensure overvoltage trip level (Parameter P5-02) is at its default or appropriate setting (if configurable for specific applications).