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..... (Electrical Question) Monster compressor: medium house.

..... (Electrical Question) Monster compressor: medium house.

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  #1  
Old 01-17-10, 08:43 AM
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..... (Electrical Question) Monster compressor: medium house.

My ultimate goal here is to never want for compressed air again. I believe that when it comes to shop infrastructure, over-building is a good thing. I have been on the lookout for an 'old-time' electric stationary all cast iron slow rpm compressor with a tank of 60 gallons or more that I can run in my home. My happy-time budget is in the neighborhood of $700 and craigslist is my very good friend.

So I found a good deal on an old Ingersoll Rand air compressor. Initially, I was certain the motor would serve in a single phase 220 capacity if I upgraded the wiring and breakers. Now I'm not so sure. Maybe I saw what I wanted to see. In any case, this monster is in my garage now and the other guy has my cash, so it's past time to learn a thing or two about this machine.

So far, I'm into this $250 for the compressor, $25 on a trailer and another $20 in gas. If wiring this old bear into my house turns out to be just too much hassle, I can live with the idea of bootstrapping a replacement compressor purchase off the sale of this one, but really, I'd prefer to just wire this IR through a lockout panel and into the wall. Currently, the circuit presents as a 250V L6-20 and is controlled by a pair of 20A breakers. The voltage actually comes from 2 seperate 20A 110V circuits sharing a common return. There is only single phase 110V in my home.

Given my compressor outlet enjoys proximity to the house inlet service panel, is there a simple option to have this house circuit path wired to adequately support the compressor?

http://www.flickr.com/photos/3221897...7623103386839/
 

Last edited by kaloalex; 01-17-10 at 08:59 AM. Reason: rework word flow
  #2  
Old 01-17-10, 09:00 AM
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Originally Posted by kaloalex View Post
So far, I'm into this $250 for the compressor, $25 on a trailer and another $20 in gas. If wiring this old bear into my house turns out to be just too much hassle, I can live with the idea of bootstrapping a replacement compressor purchase off the sale of this one, but really, I'd prefer to just wire this IR through a lockout panel and into the wall. Currently, the circuit presents as a 250V L6-20 and is controlled by a pair of 20A breakers. The voltage actually comes from 2 seperate 20A 110V circuits sharing a common return. There is only single phase 110V in my home.

So I found a good deal on an old Ingersoll Rand air compressor. Initially, I was certain the motor would serve in a single phase 220 capacity if I upgraded the wiring and breakers. Now I'm not so sure. Maybe I saw what I wanted to see. In any case, this monster is in my garage now and the other guy has my cash, so it's past time to learn a thing or two about this machine.
If you only have single phase 120 volt service to your house, you will not be able to run this compressor unless the motor can be rewired to run on 120 volt. Which it might, but you have to check the nameplate of the motor. If it will only run on 240 volts then your only options are to upgrade your electrical service or sell the compressor. I would opt for the service upgrade because I think you will have a very hard time finding a compressor that fits your needs and also have a 120 volt motor.
 
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Old 01-17-10, 10:04 AM
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Were you able to look through the link?

http://www.flickr.com/photos/3221897...7623103386839/

That's better. I seem to recall some 3-phase motors can be rewired for single phase use, but I'm not having much look finding an identification guide.

So, could you help me make sense of the situation? Is there a way to get the motor plate on the link above matched up with my house?

Thanks,
Kalo
 
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Old 01-17-10, 11:55 AM
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Old 01-18-10, 09:45 PM
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Are you sure you only have 120 volt power available? You would have to be living pretty far up in the hills to not have 240/120 power.

That five horsepower motor CAN be re-connected to run on single phase power with no loss of horsepower. The job does require opening the motor and adding three new connecting leads changing it from a NEMA 9 lead motor to a NEMA 12 lead motor. The conversion also requires about 300 to 500 microfarads of electrolytic starting capacitor along with a starting relay and about 40 to 60 microfarads of paper running capacitor. It will draw about 21 amperes on a 240 volt single phase circuit.

I've re-connected many 3-phase motors of 3-5 horsepower and never had a failure reported.
 
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Old 01-19-10, 06:54 AM
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I'm certain of very little, really.

In another hour, PG&E will start answering the phone. That's when I hope to learn just what is available in my panel.

Furd,
Can you recommend a text or source for information on placement/method for running new leads in this old motor?

Thanks,
Kalo
 
  #7  
Old 01-20-10, 01:47 AM
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Sorry, but I do not know of any site showing the re-connection to a 12-lead NEMA standard. I will help you to do the work, however.

You will need to take the end bells off of the motor, something you should probably do anyway to check the bearings and just generally clean up the motor, use a spray motor degreaser for this. Set the rotor assembly aside where it won't be damaged and then look at the stator where the existing nine connecting leads are connected to the windings. You will find the flexible leads entering into "sleeves" that insulate the point where they are soldered to specific ends on the winding. Look closely and you will see a tenth sleeve that has only three solid wires of the winding entering. This connection is known as the "star point" and is where the three new leads will be connected.

Most likely the winding will have been either "dipped" in insulating varnish and baked or it will have a spray-on insulating varnish that cures at room temperature. Either way the varnish is a bit delicate and subject to cracking at room temperature. I like to use a heat lamp positioned over the area of the winding where the star point is located, about a foot above for ten to twenty minutes (keep an eye on it) will heat the varnish to a point where you can GENTLY move the sleeve and wires out to make the new connection. Be careful as you can burn yourself. There will probably be some kind of ties, usually a cambric string or tape, that is holding the sleeves to the winding. Cut only the ties need to get the star point sleeve out where you can make new connections. Remember that the wire is stiff but can be broken so be gentle. Remove the sleeve, probably by cutting along its length.

Now you will see the physical connection of the star point, three individual wires soldered (or sometimes welded) together. Cut this connection. Using stranded wire similar to the other flexible leads (silicone rubber switchboard wire or motor lead wire is best but stranded type THHN will do) solder three new leads (one per winding) making these new leads at least as long as the other motor leads. You will need new sleeves to insulate each of these new connections and the best is a cambric sleeve but heat-shrink tubing may also be used as long as you make sure the connection is completely insulated. You then need to gently fold the new connections back against the winding and secure them to the winding using cambric lacing tape or (less preferred) small nylon zip ties. Even heavy cotton string can be used but make sure the sleeves and connections are securely fastened to the winding.

Now you need to use some spray-on insulating varnish to re-seal the connections. Use several light coats allowing the varnish to dry thoroughly between coats. I like to use the heat lamp to hasten the drying process but you have to be careful to not overheat the assembly.

You can get cambric sleeving or heat-shrink tubing at Radio Shack (or at least you could last time I checked) and they should have the cambric lacing tape also. They may even have the spray-on insulating varnish. Otherwise you can get the varnish at Grainger and a local motor repair shop would have the cambric sleeving and lacing tape.

Of course you could have the re-connection done by your local motor shop but DIYing it is at least half of the fun in making an old tool work for you.

I'll post tomorrow on identifying the new leads and how to connect to the phase converter I'll also detail.
 
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Old 01-20-10, 08:41 PM
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Furd.,

If I am reading this right you want the diagram of 12 lead motor connection that will hook up the single phase supply ?

If so let me know I am pretty sure I did have a connection diagram laying around in my Parisian house.

The other option I do suggest from time to time is get VSD { variable speed drive } so it will including a soft start so prevent drawing so much current during start up and once it get up to running speed you can able change the speed to suit your need however let me warn this very carefull especailly with compressor duty motors do not let run below 30 HZ { basically half speed } otherwise the motor will get hot due not much cool air flowing thru the motor.

The VSD it do have optional single phase input and triphase output so it will work for your useage.

Merci,Marc
 
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Old 01-20-10, 10:13 PM
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Thanks, Marc, I have the diagrams and if necessary I will post them. Before proceeding I'm going to wait and see if Kaloalex wants the rest of the details in building a static phase converter and re-connecting his motor.
 
 

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