tonyrigley

I am trying to find out what the correct gage wiring I should use to run a 300 HP 3 phase motor.

Specs:

300 HP
440 V
379 A per line
455 V between rings
293 A between rings
709 RPM Max load

What gage (or is there a formula to figure this out) wire running 150 feet from the power junction box?

We will be installing a dedicated transformer for this machine in the near future, so what would be the optimum wire gage please?

Thanks for your help.

ADDITIONAL DETAILS

Ambient temperature ranges from20° F to 110° F
Cable is run through metal conduit, all three phases run together, no other wiring
Protective device - ??? other than main breaker.

The unit is a 200 ton set of rollers used for turning flat sheets of steel ranging from 1" to 6" thick into round cans of diameters upto 14 feet accross.

Whenever we start the rollers, all the lights dim in the shop. Rocky Mountain Power assures us we have the right size transformer. We plan on putting an additonal transformer dedicated for just this machine, but we would rather not waste our money on things we don't need IF it's a different issue.

We think ithas to do with wire size. No, I can't tell you what's there now, each individual cable is about 1/2 inch diameter, and each phase has two wires bringing in power. I'm not an electrician, but I have been asked to find out more details regarding the size and type of wire to use.

Thanks again for your help.

ian.settle1

Not an easy answer as you need to know a few other things.

1-Ambient temperature
2-Is cable run with others
3-How cable is run
4-Type of protective device to be used

This is some to name