Repowering Atlas Copco LT6 Airlet compressor: bigger, slower motor??

So I have an Atlas Copco Airlet LT6 compressor coming, but it is 3ph and I only have 1ph power. Compressor is very quiet; I thought it was a diaphragm unit it's so quiet! Anyway, my rotophase will draw too much power for my 200amp service so that idea is out, and repowering the compressor is in.

I have a line on a 1200rpm, 5hp, 1ph induction motor: a big old brute, but obviously built to last forever and pretty much a sealed unit, so not a total antique. Runs well too.

The compressor has a 3ph 1750rpm motor direct coupled that puts out about 3.25hp. I can't get a 1ph version of that motor for a reasonable price.

Would the old 5hp 1ph induction motor have the torque to start and spin the compressor if 'geared up' to 1750 with belts and pulleys?

Your query is confusing. You say direct drive, are you saying that there is no belt and pulley currently? If so, Using a belt and pulley may not work because the compressor crank end bearing may not be designed for the belt thrust. Lastly, your statement that your 200 amp service is incapable of supporting your compressor is just wrong. The easiest and least expensive solution is to use a dedicated single phase to 3ph inverter. Atlas Copco compressors are top of the line units noted for their high reliability. I would NOT modify it in any way.

^^^ what he said.

I have a 40 hp rotophase, and I run a 10 hp recip compressor with it, no problems.

I have it all on a 200 amp service panel, the breaker feeding the rotophase/compressor is a 100 amp breaker.

steve-l said:

Your query is confusing. You say direct drive, are you saying that there is no belt and pulley currently? If so, Using a belt and pulley may not work because the compressor crank end bearing may not be designed for the belt thrust. Lastly, your statement that your 200 amp service is incapable of supporting your compressor is just wrong. The easiest and least expensive solution is to use a dedicated single phase to 3ph inverter. Atlas Copco compressors are top of the line units noted for their high reliability. I would NOT modify it in any way.

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Thank you for that. Maybe I was thinking about an outboard bearing to take the load I don't recall now. I'll look into the inverter question first.

I was told by the manufacturer of the rotophase I was intending to use that its starting amperage draw would be about 230 (don't recall exact figure now) and that using it on my 200amp service would probably cause light dimming or flickering nearby etc.