Parallel Phase converters

[LD1]

Quick question regarding phase converters here.

Got this 10hp rotary screw air compressor.....that was seized up. Before I invest money in figruing out how to power it (swap to single phase motor, VFD, or whatever).....I want to see if the rebuild is even gonna work.

The thing is old and in rough shape, but I figure $40 worth of bearings to rebuild its worth a shot.

So to test this thing out cheap......

I have a 10HP rotary currently wired to a 2HP bridgport, and a clausing 3HP lathe (which is being removed) and a 5hp clutched lathe.

I also have a 15HP rotary of the same MFG.

The 10HP has issues with the 5hp lathe in the higher gear ranges. Gotta really ease into the clutch.
So I am gonna Put the 15hp rotary in its place. And leave the 10HP unused.

But now back to testing the compressor, And wiring the 10hp and 15hp RPC's in parallel.

I know how to wire it, synchronize phases, all that. Thats no the issue.

The issue is do I just use the idler off the 10HP, started from the 15hp?
Or do I leave the panel intact on the 10hp...since it is more than just a starting circuit....it also has run capacitors.

Seems searching...alot of hits on practicalmachinist.....many people say just add another idler, its the easiest. But I dont want to overlook the fact that adding just a second idler does nothing for run capacitors.
Should I truly parallel both complete units, or just add the 10hp idler to the 15hp?

 

[Larry Caldwell]

I doubt that a single phase 10 hp or 15 hp would be practical unless you run it at 440 volts. We had a single phase 20 hp irrigation pump once that ran fine on 480, but it was more practical to switch to 3 phase when it became available.

Have you thought about converting to gasoline? a 10 hp or 15 hp gas engine is easily available. That much amperage at 240 v. is going to run really hot. A you figuring a 100 amp circuit for the 15 hp?

If you decide to stay with electricity, manufacturer installation data for the motors should be available online.

 

[LD1]

I doubt that a single phase 10 hp or 15 hp would be practical unless you run it at 440 volts. We had a single phase 20 hp irrigation pump once that ran fine on 480, but it was more practical to switch to 3 phase when it became available.

Have you thought about converting to gasoline? a 10 hp or 15 hp gas engine is easily available. That much amperage at 240 v. is going to run really hot. A you figuring a 100 amp circuit for the 15 hp?

If you decide to stay with electricity, manufacturer installation data for the motors should be available online.

You lost me.

Nothing is 15HP but the converter.
The compressor is only a 10HP motor.

I have a 10hp and a 15hp converter. Want to use them just to TEST the air compressor. IE, just run it for a little bit before going to a permanent solution.

Single phase 10hp motor for compressor......it isnt that high in terms of amperage. ~40a or so. But I guess its all relative. 40a may be higher than many are used to.

And a gas engine is most certainly out of the question. Dont know anyone that has a gasoline powered compressor that they have their shop plumbed with? Thats just crazy.