GA500 trips ov fault during deceleration, what to check?
My GA500 drive is tripping an 'ov' overvoltage fault every time the machine decelerates. The DC bus voltage is high when it faults. What should I check first?
An 'ov' overvoltage fault on a Yaskawa GA500 drive indicates the DC bus voltage exceeded its detection level, typically 410V for 200V class or 820V for 400V class drives. This often occurs during deceleration due to regenerated energy. The fault can also be triggered by speed overshoot, incorrect stall prevention settings, or supply surges.
Likely causes and checks
1Deceleration time too short
- Points to it
- The most common cause of an 'ov' fault during deceleration is that the drive cannot dissipate the regenerated energy quickly enough, causing the DC bus voltage to rise.
- Check
- Increase the deceleration time parameter C1-02 (or C1-04/C1-06/C1-08). Alternatively, consider connecting a dynamic braking option or running the Deceleration Rate Tuning function.
2Stall prevention during deceleration set incorrectly
- Points to it
- Incorrect settings for stall prevention during deceleration can lead to overvoltage if the drive expects a braking resistor that isn't present, or if it's configured incorrectly for a fitted resistor.
- Check
- Verify the L3-04 [Stall Prevention during Decel] parameter. Set it to 0 if a braking option is installed, or 3 if 'ov' faults occur with a dynamic braking resistor fitted.
3Speed overshoot at the end of acceleration
- Points to it
- If the drive overshoots the target speed at the end of a fast acceleration ramp, it can briefly generate energy back into the DC bus, causing an overvoltage fault.
- Check
- Increase the C1-01 [Acceleration Time 1] and C2-02 [S-Curve Time @ End of Accel] parameters. You can also enable overvoltage suppression by setting L3-11 = 1.
4Braking resistor wiring or sizing is incorrect
- Points to it
- If a braking resistor is installed but 'ov' faults persist, it could be due to incorrect wiring or the resistor being undersized for the braking load, preventing proper energy dissipation.
- Check
- Inspect the wiring of the braking resistor or braking unit. Confirm that the braking resistor is correctly sized for the application's braking load.
Next check: First, check the C1-02 deceleration time parameter and increase it if it's set too short. Also, review the L3-04 [Stall Prevention during Decel] setting to ensure it matches your braking configuration.
Related questions
Describe the fault or upload a photo, and InduQT checks it against the manufacturer manuals. Share the result here when it helps someone else.