VFDs and motors on one feeder

[slice]

Hello,I was wondering what the accepted practice is for sizing a feeder if you had for example one regular motor and two motors controlled by VFDs. The section on variable speed drives requires feeders be sized at 125% of the input current to the drive. How would this work if you had say a 10hp non vfd motor, and a 3 and 2 hp motors controlled via separate VFDs?

Would you take 125% of fla of the 10 hp plus 125% of the input currents of the vfds?

Or would you just take 125% fla of 10 hp motor plus 100% of the input currents of the vfds?
I believe the NEC isn't very clear on this point unless I am missing something, in which case I hope you guys can enlighten me.

Thanks for your help
Greg

 

[ptonsparky]

I would 125% of the largest and 100% of the rest for the feeder if I wanted minimum. The wires to each motor or VFD would need to be 125% respectively.

 

[david luchini]

Calculate the minimum feeder ampacity from 430.24...125% of the 10HP motor fla plus 100% of the other motor fla's.

Then calculate the minimum feeder ampacity from 430.122...125% of the rated input current of the power conversion equipment.

The larger value is your minimum feeder ampacity.