How many watts to run a 3 hp 230 volt air compressor?

[GmManDan]

I am looking at getting a Ir 60 gallon air compressor to use at my barn. My question is how many watts starting and running does it take to power a 3 horse air compressor? My barn does not have a heavy duty plug so I will have to run the compressor off a generator. I am not going to use it out there long enough to justify spending the money to have wire run and set up out there. I have google it already and not really come up with any thing. Any help would be awesome. Thanks

[trkklr77]

p[wattage] = e[voltage] x i[amperage]

the motor should have a max amp draw stamped on it.

[fj40guy]

Looked at IR web site.... not specified?

Northern Tool always listed current draw..... current not specified.
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_158284_158284

hp = 746 W in a perfect conversion.
Most single phase motors are around 70% efficient, so hp = 1000W (ball park guess)

So you need at least a 3KW Generator. I'd look at a minimum of 5KW generator size to run
that electric compressor. Using a gas powered air compressor is best best, but if you have
the generator and just checking to see if it will power up the compressor, I understand.


Edit:
Looked at Baldor's web site. 3hp, 230V, is rated at 13.6Amps. About 3.2KW in power, so close to my guess above. I'd still go with a minimum 5K Generator.

[ROLLIN33S]

I have a 8,000 watt cont 12k surge generac Xp generator already but I didn't want to get it and find out it was under powered. So that is good news.

[GmManDan]

I have a 8,000 watt cont 12k surge generac Xp generator already but I didn't want to get it and find out it was under powered. So that is good news.

Shit didn't know my friends screen name was still logged in. Well I went to lowes today and looked at the campbell air compressor and was not really impressed for $440 you got 10 scfm and a 60 gallon tank. They did have a 80 gallon there with 18 scfm for alittle over $600. They did not have the Ir in stock at Northern tool for me to look at it but those were the two I was looking at. The 80 gallon campbell and the Ir 60 gallon are about the same in price and air volume. Which one do you think would have better longivety?

[Pook]

Remember that the motor pulls more than the rated HP at start up. Which is a big deal especially on a compressor since it almost always restarts under a decent load.

[fj40guy]

Remember that the motor pulls more than the rated HP at start up. Which is a big deal especially on a compressor since it almost always restarts under a decent load.

Time for an unloader valve. :flipoff2:

[Mechanos]

Time for an unloader valve. :flipoff2:

Even with an unloader valve (or even zero load on the motor), the starting amperage will be higher than the running amperage.

[wl2]

I have put a clamp meter with peak amp capability on several motors and it is not uncommon to have a starting amperage 4 or 5 times the running amperage.

[sbkenn]

Simply ... 1HP is equivalent to 745W.
Add a bit for startup, but most generators have a surge rating anyway.