3 phase vs 1 phase motor

[JoSm]

Which one would be "better from an electrical perspective"? It is a 7.5 HP motor for irrigation. I understand that the 3-ph may be slightly more efficient, smaller footprint and less parts to fail, but not sure if these are enough reasons to bring a 3-phase feeder from the utility company. The only other loads will be a couple of very small compressors ( <1 HP).

 

[ActionDave]

Either will work just fine. The only question is how much will it cost for a three phase service? If that is more than you want to spend, go with the single phase motor.

 

[iceworm]

Which one would be "better from an electrical perspective"? It is a 7.5 HP motor for irrigation. I understand that the 3-ph may be slightly more efficient, smaller footprint and less parts to fail, but not sure if these are enough reasons to bring a 3-phase feeder from the utility company. The only other loads will be a couple of very small compressors ( <1 HP).

Why guess? Why ask opinions? It is an economics question - not an electrical question. Make up a bid for each. Compare the numbers.

Do it once and you will know for ever.

ice

 

[Jraef]

I understand that the 3-ph may be slightly more efficient, ...

Not necessarily. The efficiency rating is whatever you buy. You can get 90% eff single phase motors and 70% eff 3 phase motors. depends on what you are willing to pay for. It has nothing to do with how many phases you have.

... smaller footprint and less parts to fail, ...

Maybe, on the foot print, but at 7.5HP both are available in the same frame sizes, so not much. Yes on the number of parts, so 15-20 years from now someone might complain.

...but not sure if these are enough reasons to bring a 3-phase feeder from the utility company. The only other loads will be a couple of very small compressors ( <1 HP).

Not likely worth it if you ask me. If you already have single phase service, DEFINITELY not worth it. If it is greenfield, still not likely, but only your utility can answer.