# Industrial VFD conversion



## smoothflow (Oct 17, 2011)

Dear All,

Can an industrial VFD be modified so that it can accept low voltage to its DC bus link without tripping?


----------



## major (Apr 4, 2008)

smoothflow said:


> Dear All,
> 
> Can an industrial VFD be modified so that it can accept low voltage to its DC bus link without tripping?


Hi smooth,

It depends. How low is "low voltage DC"? What specific VFD? Some VFDs have adjustment to the parameter which is used for the UV limit (undervoltage). I've seen this as low as 140VDC for a 230VAC class drive. But even a 150V battery is likely to sag and trip that. It may be possible to alter some sense circuitry in the controls of the VFD and fool it but then you'd also have to compensate for that "unreal" sensed voltage in the control algorithms, which may not be possible. 

With some flexible VFDs and a stiff battery you might get away with 200VDC. But if you're talking lower than that, I don't think it is doable, aside from a few really knowledgeable engineers out there with experience with the hardware and software. 

Regards,

major


----------

