VFD MD60 AC Drive

[peng]

I have a VFD (Reliance Electric, MD60 AC Drive) running a motor on a system.

Every time I hit stop the VFD goes into a fault (F4-DC bus voltage fell below the minimum value). Every time it goes into this fault, to recover I have to cycle power. I checked the bus voltage and it's fine. Does any one know why this would happen.

 

[DickDV]

peng, I know you said DC Bus Low Voltage but, just to be sure, it wouldn't be DC Bus High Voltage by any chance?

And second, please advise whether the system is configured coast to stop or ramp to stop.

When you say you hit stop, I assume you mean that you remove the run signal from the control input. If you are opening a contactor on the AC input to the drive (not good practice) then I would expect a low voltage fault on each stop. Please confirm your stop method.

Finally, are there any contactors in the leads between the motor and the drive?