I have a 5Z405C compressor with a 10 HP 3 Ph. motor.

by Ron Bird
(Ocean Springs, Ms.)

My son works at a plant that upgraded to a large screw compressor. I can get the 10 hp. 3 Ph. comp. Can I put a 7 1/2 HP or 5 HP motor on this pump? It is a model 5Z405C? I don't have 3 Ph. at home. Thanks Ron





Bill responds...

Howdy Ron. Thanks for writing in.

It's your compressor, so you can do anything you want with it, including downsizing the motor.

Interfacing a new motor is not complex, as long as you can manage the shaft size (if there is a discrepancy) and figure out how to match the mounting holes.

The issue then is, will the compressor run properly?

Each compressor is engineered to run properly with similar components. If your unit would have run satisfactorily with a 5 HP motor rather than a 10 HP motor, why use the 10 HP? I expect it's because the mechanical design of your compressor requires the force generated by the 10 HP motor to properly compress the air.

If you downsize the motor, will the compressor still do that effectively? I would guess not?

Will you wear out a smaller motor sooner? I would think yes you would.

The issue arises when folks try to put a larger motor on a compressor than the one that came with the compressor. A too-large motor may create problems just like a too small motor will.

However, as I say, it's your compressor. If you have the time and like to tinker, go for it. All that can happen is that the new hybrid compressor won't work to your satisfaction and you may have some early component failure. And then, of course, you have one more thing to tinker with.

Cheers,

Bill





Comments for
I have a 5Z405C compressor with a 10 HP 3 Ph. motor.

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Jun 18, 2011
 Not the way to go.
by: David S.

You have a screw compressor, which has a need for a strong starting and running motor. When you go from a 3 ph to a 1 ph you are losing power. You also wanted to downsize the motor. Bad idea. You are then putting a tremendous strain on the motor which will burn out rapidly.
A much better idea is to make yourself a rotary
phase converter, or locate one on the internet that
will convert your 1 ph to 3 ph, and give you all the
power you need. Generally a 7.5 hp 3ph used for a
rotary phase converter will take care of that 10 hp
3 ph motor.

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