effect of low frequency input for VFD

[hussamaldean]

Hi all,
I don't know if this is the right section for this post, if it is not then feel free to move it to the correct section
let say a vfd is used with lower frequency than 50HZ, say 30Hz. Will the device suffer issues with such low frequency or not ?
waiting for your answer

[Ian.M]

Yes its likely to have issues, as it wont have enough reservoir capacitance on the DC bus to maintain its full load output between peaks of the rectified supply.

Assuming three phase input, its also likely that it will sense a problem with the input power and shut down at some frequency below its nominal operating range but above your supply frequency.  Single phase input VFDs are less likely to have power quality sensing that will trip on low supply frequency.

If it doesn't shut down, it *may* be possible to run it at a proportionally derated output current without ill effects.

[Jeroen3]

This is a bad idea. See if you can supply DC directly yourself.
Or explicitly ask the manufacturer for derating or operation with lower line frequencies.

Theoretically the VFD should be capable of working with lower frequencies.