A client ordered a 240 V motor with a VFD and they want to connect it to a 208 V panelboard. Will this not matter since the motor is ran by the VFD? How would I calculate the FLA since the nameplate data is based on 240 V?
The VFD approximates its desired output by summing up a large number of on-off pulses of DC directed to the proper windings as the motor turns.
The DC is obtained by rectifying the input AC. That means that the DC available will not be more than the peak of the input AC waveform. For 208V AC that would be 294V DC.
When you reverse the process, there is no way that the VFD can take that 294V DC and use it to replicate a 240VAC waveform which peaks at 340V DC.
If the motor is not fully loaded, you may be able to get away with the VFD feeding it only 208V or less when it is running. Or maybe not.
You may have to install a boost transformer set on the input of the VFD.
FLA(208) (fully loaded, which you may not have or the motor may not tolerate) will be 240/208 times the 240V FLA.
Bottom line: If the motor can run directly off 208V, then you can run it off the VFD. If not, you probably cannot, unless the motor will be operating at reduced speed and voltage only.