On 3 Jul 2005 03:18:17 -0700, "gtslabs" wrote:

I have had problems getting my 10 hp 2 stage compressor to run on my 10
hp rotary phase converter from Andersons. It is currently wired for
240v at 1750 rpm. Can I replace the motor with a smaller hp motor and
possibly a smaller rpm or would I also have to change some pulleys too?
I am mainly using it for a large sandblast cabinet so I don't need a
real high psi.

What are the advantages/disadvantages of using a DC motor to drive an
air compressor?

You'll want the HP if you're sandblasting.

You'd need rectifiers to run a DC motor. That's easier than a rotary
phase converter.

If you can find a 10 HP 240-volt DC motor with about the right speed,
I see no reason why it wouldn't work well. They're not real common,
but they do exist. It could work particularly well if you could
contrive a starter that applies heavier field current for starting.
This would actually reduce total starting current because heavier
field current produces more torque at lower speed for given armature
current.

It's real hard to beat DC motors for starting torque. That's why
they're used as "traction motors" on things like diesel locomotives.