Electric Motor Question?

Question

I want to run a 20 HP 3-Phase AC Electric Motor from a battery bank. The Motor is rated at 240 Volts @ 64 Amps. I want to control the Motor through a variable frequency Drive With 240 volts DC from the Battery Bank of 20 12 Volt batteries. What size batteries should I use to run the motor at nearly full load (50 amps) for one hour?

The Power from the batteries will be fed through a DC to 3-Phase Variable Frequency Drive. I have a Charger for the 240 Volt Battery bank. Using a Rotary converter will not work for this application. The Batteries will consist of Deep Cycle batteries, a series/parallel connection if necessary. Specifically, what amp hour batteries will I need (Amp hour of each 12 Volt Battery)?

Answer 1

These batteries would be huge to be able to supply the amount of amps you'll need.
You'll also want to get 'deep discharge' batteries.
The best way to get the 3 phase power would be to get a DC motor- 3ph generator combo.
Also think, how will you recharge the batteries, since I assume you have no regular power there?
I have set such things up with using 240 single phase to 3 phase motor generators.

Answer 2

Do you have a 3 phase inverter? You need to convert the DC to AC and then run through the VFD. I doubt that you are going to get 50A for a hour unless you parallel some more batteries with the ones you have in series. Deep cycle marine batteries would probably be your best choice.

Good luck

Answer 3

I'm not an electrician, but if you can get a setup to work like that, you'll need "deep cycle" batteries at least. Those are pricey... Where are you going to put the inverter?