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What’s the wattage for a 3 1/2 HP air compressor?

by darrell
(palm bay fl)

i have a 3 1/2 horsepower 10 gallon tank and was wondering what size generator ill need to have it run properly

Darrell, according to www.google.com/intl/en/help/features.html#calculator, 1 horsepower = 745.699872 watts

I am not an electrician nor a motor mechanic so my advice is suspect. Yet, is it logical to think then that you will need at least 2500 running watts? Inrush will require more.

Any electrical gurus out there can help Darrell?




Generator for  compressor
by: Jim

I’m not an engineer…but here goes:

P=EI for the power formula in watts

Therefore, 120 x amps of the motor = number of watts that your generator will need to deliver when running the compressor.

However, a compressor is a inductive load device, and the same as a fridge when it first comes on, lights dim and there’s a power inrush until the motor comes up to designed speed. So while it comes up to speed it sucks more current than at normal running speed.

And this lower run current (start up inrush) must be factored into the generator’s size.

Honda.ca show this in their generator chart.

So you will wind up selecting a generator bigger than the compressor’s running watts to cover the start up load, and then maybe go to the next size bigger for winter compressor use when both the generator oil and the compressor oil is thicker – it could use the next size up to handling the load, help like having a big V8 under the hood, even though a 6 cylinder might do the job.

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