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Can i convert this compressor to single phase 220?

Savedbygrace77

Aluminum
Joined
Jul 15, 2018
Looking at a huge 120 gal industrial compressor for real cheap! issue is it has a 3 phase 15hp motor.. ive read about running a 10hp motor, will the reduced torque of a single phase 10hp work? Im not going to be pushing this thing hard at all - just occasional sand blasting and I want something that will kick the pants off my jobs - hate slow sandblasting and my current little thing is lame!


Here is a shot of the motor and compressor:

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375b678a345d40948bb908d3b70021cb.jpg

compressor2.jpg
 
Changing motors is simple but loosing 5HP is going to reduce the compressors qualities. The biggest thing is the 10 HP motor is likely not going to have enough power to run the pump at the current speed without overloading the motor. Slowing the pump speed (likely needed) is going to reduce the recovery time by whatever ratio the pump was slowed by, it should still put out the same maximum pressure thought.
Dan
 
Not a mechanical engineer, but as said above you are probably going to have to drop the pulley size about 1/3. The unit has a 15hp motor for a reason. You may be able to lower the minimum and max pressure by adjusting the air switch to get it to run cooler without dropping the pulley size.
 
Not a mechanical engineer, but as said above you are probably going to have to drop the pulley size about 1/3. The unit has a 15hp motor for a reason. You may be able to lower the minimum and max pressure by adjusting the air switch to get it to run cooler without dropping the pulley size.

Yeah was thinking of reducing the pulley, theres no way id need 200psi!! heck id probably run it at 100.. more of a volume thing than max psi...
 
If you look at the pumps, most of them are designed to run on multiple motor/pulley configurations. Chances are you can get a smaller, single phase motor, look up the correct pulley and put it on. I know my compressor came from the factory with a 5, 7.5 or 10hp motor. The pulleys increase in size, requiring a bigger motor, but drive the pump faster to put out more CFM. Like mentioned, you will lose CFM going to smaller motor, but even with a 7.5 or 10, should be well above 20CFM. I have a similar Champion with a 5hp that puts out like 18cfm. More than enough to run a single blast cabinet.

Gives you an idea of the ranges. Look through here.

R-Series Lubricated (2-3 HP) Reciprocating Air Compressor

Where are you in CA? Might actually take the 15hp motor off your hands if you want....
 
Using the same size driver as the 15 hp would limit the pressure to 2/3 of what it could originally produce. Using a driver of 2/3 the original size would produce 2/3 the original volume but could achieve the same pressure as the 15 hp.
 
Using the same size driver as the 15 hp would limit the pressure to 2/3 of what it could originally produce. Using a driver of 2/3 the original size would produce 2/3 the original volume but could achieve the same pressure as the 15 hp.

If you size the motor down, you need to decrease the drive pulley for more torque, otherwise you can stall the motor, or it will at the very least be very hard on it every time it starts. Then the smaller motor can drive the pump, but you lose the speed and therefore limit the CFM output. But in his case, even with a smaller motor, will still be more than he needs.
 
I bought a 120 gal compressor with 5 hp single phase motor. I'm replacing the motor with a 5hp three phase motor with Allen-Bradley VFD. This will allow a soft start phase before full speed.

What you propose would work. If you are going to go with a new 10hp single phase motor have you looked at the cost versus a three phase motor with VFD?
 
If you look at the pumps, most of them are designed to run on multiple motor/pulley configurations. Chances are you can get a smaller, single phase motor, look up the correct pulley and put it on. I know my compressor came from the factory with a 5, 7.5 or 10hp motor. The pulleys increase in size, requiring a bigger motor, but drive the pump faster to put out more CFM. Like mentioned, you will lose CFM going to smaller motor, but even with a 7.5 or 10, should be well above 20CFM. I have a similar Champion with a 5hp that puts out like 18cfm. More than enough to run a single blast cabinet.

Gives you an idea of the ranges. Look through here.

R-Series Lubricated (2-3 HP) Reciprocating Air Compressor

Where are you in CA? Might actually take the 15hp motor off your hands if you want....

Thanks - ill have a look.. in San Pedro - ill let u know how things go :) check on me in 2 weeks.. byt hen ill be somewhere further down the road of deciding what i wanna do :)
 
I bought a 120 gal compressor with 5 hp single phase motor. I'm replacing the motor with a 5hp three phase motor with Allen-Bradley VFD. This will allow a soft start phase before full speed.

What you propose would work. If you are going to go with a new 10hp single phase motor have you looked at the cost versus a three phase motor with VFD?

Ive looked aorund - so ur saying even a 5hp is enough to replace a 15hp 3 phase? isnt that pushing the motor a little hard? as far as i have seen jumping from 10 to 15hp makes the parts almost double in price.. i guess 15hp really is big end stuff compared to most small shops..

i saw some vfd inverters for a few hundred dollars - is that what i am looking for? ie would i be able to run it on 220 single phase with one of those?
 
Is the pump splash lubricated or oil pump? Splash lube has a minimum rpm to be effective probably 700-900 rpm. You can run that motor on a ten HP VFD if you switch pulleys around to use what a 10hp motor would use. The motor will max out at ten hp amp draw if you set the parameters right. My 3hp lathe came with a 1hp VFd and ran fine just did not have the hogging power of 3hp.
Most folks 120-150 PSI max is plenty
Bill D
 
Ive looked aorund - so ur saying even a 5hp is enough to replace a 15hp 3 phase? isnt that pushing the motor a little hard? as far as i have seen jumping from 10 to 15hp makes the parts almost double in price.. i guess 15hp really is big end stuff compared to most small shops..

Not exactly. The 120gal with 5hp motor is how my compressor was put together. A 10Hp single phase motor probably would have been better. Eventually a start capacitor exploded and a winding might have to be replaced. My compressor has such a large heavy flywheel that a softer way to start it spinning is what I want. If I had a 10Hp 3 phase motor and properly sized VFD then that would be better.

i saw some vfd inverters for a few hundred dollars - is that what i am looking for? ie would i be able to run it on 220 single phase with one of those?

You should understand about the derate factor that might have to be applied to your particular VFD. Then there is the pulley diameter size. For me the 5 Hp motor and VFD combination are spares and that is what I will use. The easiest thing for you is to get a VFD. Cost, sizing down is going to be your decision.
 
I have a Ingersoll-Rand 2 stage that had a 15HP 3 phase motor on it and I replaced the motor with a 10HP single phase motor and it works perfectly for my use. My main use is sand blasting and it will keep up on the air with no problem and will actually pump more air than needed and will shut off while sand blasting. I don't need the high pressure that it is capable of and have the pressure switch set at 100 psi.
 
Thats what I did,bought an Em-Glow 2 stage 22CFM,and put a 12 Kohler engine on it,So now I have a small Campbell and a 60 gal tank for shop use I keep it inside,,fer winter,keeps it warm.And outside I have the Emglow 12HP gas compressor,+ I have a Schramm 125Cfm all hooked together,when I need more air I run what ever 1 I need at the time for my air demand..
 
Looking at a huge 120 gal industrial compressor for real cheap!

So it's really not "Real cheap" eh ?

You need to really look for something better.

Try looking for something a little bit smaller.

Also , I have not seen any indication of incoming powerline available.
 
I have a Ingersoll-Rand 2 stage that had a 15HP 3 phase motor on it and I replaced the motor with a 10HP single phase motor and it works perfectly for my use. My main use is sand blasting and it will keep up on the air with no problem and will actually pump more air than needed and will shut off while sand blasting. I don't need the high pressure that it is capable of and have the pressure switch set at 100 psi.

thats pretty much what im considering - and exactly what i wanna do with the machine.. thanks for the input..
 
So it's really not "Real cheap" eh ?

You need to really look for something better.

Try looking for something a little bit smaller.

Also , I have not seen any indication of incoming powerline available.

Considering that these things are new around 2-3k, yes incredibly cheap is applicable if u knew what im paying. currently shop has single phase and i can wire in to 220.. im looking at options to work around the 3 phase motor.. I think thats why the guy is letting it go cos of the limitations for smaller non industrial setups ...

besides I have plenty of room for the thing.. it just about fits on a pallet and i might even build an outside enclosure for it.. there are some perfect unused nooks around the building. I work on boats and now and then i like to sandblast something and dont wanna sit around all day doing it, hence the larger size (and price - again!)
 
Considering that these things are new around 2-3k, yes incredibly cheap is applicable if u knew what im paying. currently shop has single phase and i can wire in to 220.. im looking at options to work around the 3 phase motor.. I think thats why the guy is letting it go cos of the limitations for smaller non industrial setups ...

besides I have plenty of room for the thing.. it just about fits on a pallet and i might even build an outside enclosure for it.. there are some perfect unused nooks around the building. I work on boats and now and then i like to sandblast something and dont wanna sit around all day doing it, hence the larger size (and price - again!)

No really ?

Not that I would actually do what your trying to do.....

And yet, all these words, no actual numbers (we like numbers here)
of just what electrical service you have.
 
In your initial post you mention “losing” torque by going with single phase. That is untrue, whomever told you that is wrong. Torque in a 3 phase motor is applied more SMOOTHLY than in an equally sized single phase motor, which can show up in machine tools doing cutting (like lathes and mills) as tool marks, but on something like a compressor, there would be no difference whatsoever. HP is a function of speed and torque, so a 10HP motor at the same speed produces the same torque regardless of how it is powered.
 








 
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