VFD sizing

[Zorak]

Can someone direct me either to a site, previous thread, or good reference book that discusses proper VFD sizing. In searching, I have found various answers all different.

I am sure that I need to base it off the FLA of the motor and not its rating, but I have seen sizing based just on the FLA to two times the FLA. Further, I am sure that there are other considerations that need to be taken into account based on the motor type and application.

If someone could point me in the right direction, I would appreciate it.

Z

 

[DickDV]

You need to start with the load torque. Determine what that is and then determine the motor amps needed to develop that torque. You will need to identify both the continuous and the short-term peak torque. So, you will end up with short-term and continuous amps.

Use that to size the drive. Do not use hp. Use short-term and continuous amps and pick the drive to cover both.