3 phase compressor to 220 rewiring

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Old 05-07-10, 09:06 AM
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3 phase compressor to 220 rewiring

I am considering buying a compressor from someone. It sat in storage for a few years so I assume I should take a couple of steps before I fire it up. How should I get it ready?
Also, it appears it is currently wired for three phase. How do I go about getting it down to 220?
I hope the link to the pictures works. I did something wrong last time and someone fixed it for me.

Well, I see I did something wrong so here's the link to Picassa Photos.
http://picasaweb.google.com/andrewpa...q-jcWswOLvzwE#
 

Last edited by 2muchgrass; 05-07-10 at 09:19 AM. Reason: Picture didn't show.
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Old 05-07-10, 09:56 AM
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The cheapest way to convert from 3 phase to regular household 220/240 is to replace the motor.
 
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Old 05-07-10, 10:32 AM
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Basically converting a 3 phase motor to a single phase is not possible. Sort of like converting a car to a motorcycle. There are ways to provide 3 phase power from single phase service but unless you have another 3 phase motor in your junk box as Pilot Dane said switching motors is your best option.

The fact you wrote:
Also, it appears it is currently wired for three phase. How do I go about getting it down to 220?
Seems to indicate you are confusing voltage with what 3 phase means. 3 phase is not an indication of voltage.

You might want to post over in the electrical forum because this is really an electrical question.
 
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Old 05-07-10, 11:43 AM
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Since there are only two incoming power leads and it appears only two motor leads that is not a three-phase motor.

Ray, a star (or wye) connected three-phase motor CAN be reconnected to run on single phase power. It requires a couple of capacitors and a starting relay and also requires connecting three more leads internally. I gave a fairly comprehensive reply to someone asking in the electrical forum a couple of months ago but they never returned so I didn't give the final steps.
 
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Old 05-07-10, 12:17 PM
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Originally Posted by furd View Post
Ray, a star (or wye) connected three-phase motor CAN be reconnected to run on single phase power. It requires a couple of capacitors and a starting relay and also requires connecting three more leads internally. I gave a fairly comprehensive reply to someone asking in the electrical forum a couple of months ago but they never returned so I didn't give the final steps.
And the really embarrassing part is I use to be a 3 phase motor mechanic.
Sorry for the misinformation.
 
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Old 05-07-10, 09:29 PM
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Upon closer examination

Soon as somebody mentions 3 phase, my brain shuts down and refuses to see the obvious.
I looked again tonight and indeed, there are only two wires supplying the unit. Then, I remembered the guy saying that the last place he had it installed did not have 3 phase so he had it running off of regular 220.
Ok, we have the power supply figured out. Now, what should I do before I fire it up? The wheel turns freely enough.
Once I get power, should I just jog it a bit or just flip the switch and let her have at it?
How about compressor oil. I've only ever had oiless compressors.
 
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Old 05-07-10, 09:47 PM
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You should have no problem letting the unit run.
30 weight non-detergent motor oil is what you can use in your compressor.
It is the same as what is labeled compressor oil only considerably cheaper.

It should be available at most larger auto parts stores.
 
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Old 05-07-10, 10:20 PM
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Change the oil first and then look at the motor nameplate to be certain that it is a single phase motor. It should specify 120/240 volts. You might want to double check the wiring to be certain it is wired for the higher voltage before connection. If the nameplate reads 208-220/440 volts then it is a three phase motor.

It might have stuck valves if it has set for a long time. Post a few pictures of the entire thing so we can see your beauty.
 
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Old 05-08-10, 07:52 AM
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More pictures

Last night I did a temporary wiring job, held my breath and flipped the switch. It started up and purred like a kitten. In two or three minutes it switched off and my heart sank. "What could be wrong?" I wondered. I checked the breakers, the connections and the wire. Everything was fine. Then I looked at the gauge. 150 pounds. I hooked up an air line and put a wand on and cleaned the dust off of it and the cooling fins and it came on again.
I think I'm going to buy it. The owner said if I want to sell it for him, I should ask $800 and I can keep anything over $400. Or, I can buy it for $400 and pay him what I can, when I can.
I don't think I should let this one go by me.
Oh, and if anyone is thinking that it was easy getting it up into the truck by myself, let me correct you. It was NOT easy.
Now I have to find a place for it and get it back off the truck.
When I get it down and set into place, I will change the oil as suggested and make sure it is drained of water. There aren't any oil level indicators that I can see but there is a gauge. It sits at about mid level.
Just above the gauge, you will see a valve. the line from it goes to some sort of device. What is that? A bypass or something?

The pictures are here.

Picasa Web Albums - Andrew - Compressor
 
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Old 05-08-10, 09:45 AM
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Originally Posted by 2muchgrass View Post
Last night I did a temporary wiring job, held my breath and flipped the switch. It started up and purred like a kitten. In two or three minutes it switched off and my heart sank. "What could be wrong?" I wondered. I checked the breakers, the connections and the wire. Everything was fine. Then I looked at the gauge. 150 pounds. I hooked up an air line and put a wand on and cleaned the dust off of it and the cooling fins and it came on again.
I think I'm going to buy it. The owner said if I want to sell it for him, I should ask $800 and I can keep anything over $400. Or, I can buy it for $400 and pay him what I can, when I can.
I don't think I should let this one go by me.
Oh, and if anyone is thinking that it was easy getting it up into the truck by myself, let me correct you. It was NOT easy.
Now I have to find a place for it and get it back off the truck.
When I get it down and set into place, I will change the oil as suggested and make sure it is drained of water. There aren't any oil level indicators that I can see but there is a gauge. It sits at about mid level.
Just above the gauge, you will see a valve. the line from it goes to some sort of device. What is that? A bypass or something?

The pictures are here.

Picasa Web Albums - Andrew - Compressor
just currious-is it sitting in the back of the old ford truck you were working on?
 
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Old 05-08-10, 11:24 AM
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Ummmm, yes, it is. And how would you know that, my friend?
 
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Old 05-08-10, 11:38 AM
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That is a two-stage Quincy, definitely a keeper! The device immediately above the shaft cover and on the left side is an automatic unloader valve. It is possible that machine originally had a gasoline engine driving the compressor pump because unloaders like that are rarely used on electric drives. The unloader is adjustable to maintain a set pressure by opening the suction valves when the pressure rises to the set figure.

That machine also has a pressurized lubrication system. Quincy is one of the best names in smaller (under 100CFM) compressors there is and that machine is worth every bit of $400. I envy you.
 
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Old 05-08-10, 12:42 PM
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Originally Posted by 2muchgrass View Post
Last night I did a temporary wiring job, held my breath and flipped the switch. It started up and purred like a kitten. In two or three minutes it switched off and my heart sank. "What could be wrong?" I wondered. I checked the breakers, the connections and the wire. Everything was fine. Then I looked at the gauge. 150 pounds. I hooked up an air line and put a wand on and cleaned the dust off of it and the cooling fins and it came on again.
It likely shut off because it hit the cut off pressure. 150 psi. Sounds like a good deal.

BTW - If it was 3 phase you could have easy bought a static or rotary phase converter for about $130 (static)
 
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Old 05-08-10, 06:57 PM
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I'm in trouble now!

Originally Posted by furd View Post
That is a two-stage Quincy, definitely a keeper! The device immediately above the shaft cover and on the left side is an automatic unloader valve. It is possible that machine originally had a gasoline engine driving the compressor pump because unloaders like that are rarely used on electric drives. The unloader is adjustable to maintain a set pressure by opening the suction valves when the pressure rises to the set figure.

That machine also has a pressurized lubrication system. Quincy is one of the best names in smaller (under 100CFM) compressors there is and that machine is worth every bit of $400. I envy you.
That's wonderful news to hear! Thank you!
I am, however, in trouble at the moment. I have been working a good part of the day making a place for it and getting ready to get it off. I made a wheeled base for it (mistake), set up a pair of ramps, a come-along and a pair of cargo straps to control the descent.
As you can see from the last four pictures (Picasa Web Albums - Andrew - Compressor), my precautions weren't enough.
I think I'll take a break and rethink this. I believe I'm going to winch it back up into the truck and maybe take the wheels off.
They seemed like a good idea at the time.
I can't think of a piece of equipment that would help me here other than a back hoe.
 
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Old 05-08-10, 08:24 PM
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Wink

Originally Posted by 2muchgrass View Post
Ummmm, yes, it is. And how would you know that, my friend?
i recalled the user name '2muchgrass' when diagnosing a 300" 6cyl carb/timing problems.
 
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Old 05-08-10, 08:33 PM
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Yup, that would be me. And when you said "the old ford truck you were working on?", the part "you were working on" is redundant. It is assumed that if you have an old Ford truck, you are working on it...always. Off topic, sorry. Now I'm going down to try to get the compressor back into the truck and try to figure out a better way to get it out.
 
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Old 05-08-10, 08:35 PM
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You could likely get this off your truck with some 2 x 10 lumber fastened to the base rather that the frame you made and some braced 2 x 10 lumber to slide it down but it would be safer and likely cheaper to get a loader or forklift to do this for you.

Not sure about your area but local lumber yards here will move something with their forklift for a very reasonable price since they make their money selling wood, not as equipment movers.
 

Last edited by GregH; 05-08-10 at 09:04 PM. Reason: Typo
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Old 05-08-10, 11:59 PM
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I sat and thought a bit, got up and tried again. I left the wheels on but took my time and went inch by inch. It's down and in the shop. I still have to move it to it's final destination which is all the way on the other side of the house in it's own room. I will change the base to wood and use pieces of pipe to roll it to it's home.
When I change the oil, how much do I put in? There isn't a sight glass or a fill line that I can see.
 
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Old 05-31-10, 09:10 AM
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oil fill

on the crankcase opposite the motor youll notice a round nob sticking up, thats a dipstick, pull it out, should take about 4 quarts..30 wght non deter drain is on the bottom of the crank opposit the flywheel
 

Last edited by rise2surge; 05-31-10 at 09:14 AM. Reason: update
 

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