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3 phase shop air compressor Electrical Question

Discussion in 'The Hokey Ass Message Board' started by Dirty30Dodge, Jul 7, 2012.

  1. Dirty30Dodge
    Joined: Jan 10, 2009
    Posts: 471

    from Argyle, TX

    Hey guys
    I was looking at buying this compressor to run my sand blaster and tools. I am not sure about the 3 phase. Can it be wired into my fuse panel at the house without any big expense. I have a 220 outlet already in my shop can i just wire a plug on it? Will this start on its own? If not what is my best option on wiring it up? Or should I just pass and get a single phase? Thanks

    Model # CAPRSA15
    •Mounted Magnetic Starter: Yes
    •Vibration Isolators: Yes
    •Automatic Tank Drain: Yes
    •Low Oil Level: Yes
    •Air Cooled After-cooler: No
    •Motor: 5 hp
    •Tank Size: 80 gal
    •Pump Model: R-15B
    •Shipping Weight: 535 lbs
    •Voltages Available: 230/3
    •RPM @ 125 PSI: 805
    •CFM Displacement @ 125 PSI: 23.5
    •CFM Delivered @ 125 PSI: 19.1
    •RPM @ 175 PSI: 710
    •CFM Displaced @ 175 PSI: 20.7
    •CFM Delivered @ 175 PSI: 16.5
  2. You will need a "phase converter" that's rated for you 5hp motor.
    There's a few different kinds of them. Google will lots of info on phase converters.
    Sometimes the 3 phase equipment is dirt cheap because of that.
    Joined: Aug 10, 2008
    Posts: 2,586


    NO you can't just plug it in
    I bought a single phase motor for mine and sold the 3 phase
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  5. gas pumper
    Joined: Aug 13, 2007
    Posts: 2,948

    gas pumper

    With a phase convertor you are esentially running the motor on 2 of the 3 legs. SO it will have 2/3 of 5hp=3.3 hp. Not so good for an air compressor, sometimes ok for other machine tools.

    See if you can sell the 3 ph motor and replace with a single phase 5 hp.
  6. Meyer
    Joined: Sep 9, 2007
    Posts: 379


    Get a single phase 5hp or a phase converter will run you a few bucks. In my machine shop we have an American Rotary phase converter. Had it 5 years and all good. Good if you are ever going to get another machine, like a mill or lathe that is 3 phase.
  7. Dirty30Dodge
    Joined: Jan 10, 2009
    Posts: 471

    from Argyle, TX

    OK i see phase converters under $80 so I may just get this if I can get it cheap enough found this site

    Thanks everyone as usual you guys Rock !
  8. Really, I see a 5 HP rotary that provides full power for 900.00
  9. squirrel
    Joined: Sep 23, 2004
    Posts: 44,071


    Compressors take a lot of power to start up, don't be surprised if it doesn't work with a cheap phase converter.

    If you don't have 3 phase power, you'd be better off buying a single phase compressor.

    If you are planning on getting some machine tools later, that might be 3 phase, that's still not a very good reason to buy a 3 phase compressor, because you can use a small inexpensive electronic VFD to run a 3 phase lathe or a mill.
  10. Mr48chev
    Joined: Dec 28, 2007
    Posts: 25,972


    The guys are correct. If you don't already have three phase electricity to the property pass on the three phase motor.

    My friend with the welding/machine shop here in town has had his old 3 phase compressor out of his old shop for sale cheap for the three years he has had his new shop and can't get a taker on it.

    Three phase equipment is great if you are already set up for it but the cost of having the power company running a line and transformer for it along with the cost of a panel and wiring and the added cost of "demand rates" for the power that you used are prohibitive unless you are running a commercial shop in most cases.

    There are plenty of 80 gallon 5 or six hp 220 single phase compressors out there rather than pay the cost of that one along with shipping and then add 3-400 dollars or more for a 220 motor to run it.

    Up here the ag related stores that cater to the farm/ranch folks usually have the best deals on big 220 air compressors.
  11. ems customer service
    Joined: Nov 15, 2006
    Posts: 2,553

    ems customer service

    another option often overlooked is to have 2 compressors, use one for the light duty demand and then turn on the 2nd (running two at the same time) for the large demand, the 2nd compressor could be gas driven and put outside in its own little shed.

    also when hooking a sandblaster, put a 5 or 10 gal tank about 2 feet past the air connection for the blaster it helps air flow
  12. gas pumper
    Joined: Aug 13, 2007
    Posts: 2,948

    gas pumper

    this is a great tip. ^^^^^. I run an old 40 or so gal tank before my sand blaster to act as a buffer and cooler. And than a 1/2 ID hose from that tank to the blaster. I also have a regulator going into that tank so it's only at 60psi, the blaster likes the lower pressure.
    Joined: Jun 3, 2005
    Posts: 7,829


    How much for the compressor? The pump is surely up to the task with those CFM ratings, and that same gig in single phase would be very costly. Get quote from Grainger for a 1PH 5HP motor with that same frame and RPM rating. If with that motor and the compressor purchase you find the investment well below the alternative of finding 1PH, you have your answer. I paid $650 out the door for a Farm Duty 1PH 10HP motor for my home compressor. It was cheaper than selling off the compressor and replacing it with 1PH 5HP. Now I have 35CFM, 10HP, and a much cheaper electric bill than if I had gone the other way. And a phase convertor for me would have used way more amperage, cost over double the cost of the motor, and I woulda been just over 7HP for my trouble and expense. Think it through and use the 'net to design to your needs. It CAN be done...
  14. A phase convertor is not the best idea for an air compressor. However, Look into a 5 Hp VFD (Variable Frequency Drive). You should be able to find one that takes 220 single phase input and outputs the correct 3 phase voltage and amperage for that motor. VFD's are used alot in industry and can often be found at equipment auctions cheaply. I have installed a number of VFD's at work (ranging from 1.5 to 30 Hp) and I have yet to be disappointed by the performance.

    Good Luck
  15. squirrel
    Joined: Sep 23, 2004
    Posts: 44,071


    Have you ever run a compressor off a VFD?
  16. MEDDLER1
    Joined: Jun 1, 2006
    Posts: 1,593


    I dont believe they will work with a piston unit because of the way they run. They cycle (start stop) unlike a lathe or mill. They do however use them on rotory screw type units all the time.Im sure squirrel knows this Im not answering to him, But they also run continuous and do not stop running when unloaded. I should know this ( I work for Quincy ) honestly I have never asked why they dont . But I will on monday. So right now Im guessing......
    Also I believe the start up (loaded start) would have a pretty high amp draw in wich case you would have to have a pretty big vfd theres got to be something to that.....
  17. Nope, But I have run a hydraulic power unit off one. That worked quite well. Similar application, starts and stops as fluid pressure was required. The hydraulic unit powered a press that would get moved around the factory, and there wasn't always a 3 phase plug in available.
  18. Kirk Hanning
    Joined: Feb 27, 2005
    Posts: 1,604

    Kirk Hanning

    I'm runnig a 3 phase Bridgeport off my garage. I bought a 5 HP American Rotary phase convertor to make it all work. It's definitely a quality piece and doesn't cost that much to run especially seeing that I run the Bridgeport as neeed maybe 4 hrs a week tops. They suggest running a convertor rated at a higher HP than what is needed + you can always add equipment at a later time. My Bidgeport is 2 hp so I bought a 5 HP rotary phase convertor. Stay away from static phase convertors as they provide the third leg at intial startup then your running on 2 legs which is single phase. Not only is the electric motor only running on 2/3 power but you decrease the life of the motor greatly.
  19. Wicked50
    Joined: Apr 14, 2008
    Posts: 882


    Wouldn't a 3 pole breaker and some panel rearranging work
  20. GTS225
    Joined: Jul 2, 2006
    Posts: 1,128



    No.....It's not about how many wires you can feed to the equipment from your panel. It's about having the three-phase power into your panel.

    The phases are actually 120* apart, (if graphed correctly), due to the way the municipal generator was manufactured. Three windings on a rotary central core, spinning at either 1800 or 3600 rpm. It takes time for each winding to rotate that 360* of the core, thus generating three-phase power.

    Most municipalities will not run three-phase to a residence.

  21. squirrel
    Joined: Sep 23, 2004
    Posts: 44,071


    If you have 3 phase power coming into the building it would. Usually you only find 3 phase power at larger commercial buildings.
  22. MEDDLER1
    Joined: Jun 1, 2006
    Posts: 1,593


    So I talked with the guy at my shop that does the most VFD stuff and he says it can be done on a piston unit but the cost and work would be alot more than just getting a single phase motor. He was concerned with to low of voltage going to the motor and causing heat issues as well as not bieng able to spin the correct rpm wich could be an issue if the unit is pressure lubed. Over heating the motor was the main one in wich he said would burn it up prematurely. Lathes and mills generally are 1/2 to 2 1/2 Hp motors and they do not need as much power and thats why people can use the VFDs.
  23. Can you explain a little further? Would mounting one of those five gal. portable air tanks in line next to the blaster do the trick? If so, what are the benifits?
  24. 57JoeFoMoPar
    Joined: Sep 14, 2004
    Posts: 4,306


    Great info there. If you're going to run 3 phase, go with a rotary converter all the way. If you're hooking up a shop or garage where you're going to be for some time, step up and get the 3 phase, you'll be able to get all kinds of crazy powerful tools dirt cheap because you'll be equipped for 3 phase.
  25. Has anyone here actually had 3 phase installed in a residential area? Costs involved, red tape?
  26. I don't think they would do it. Maybe if you lived next or close to an industrial complex they might give you a 3 phase drop.
  27. swissmike
    Joined: Oct 22, 2003
    Posts: 1,276


    Go to eBay. You can buy good quality 5hp single phase motors for $200-400 all day. This is a no-brainer in my book. Did the same to a compressor I got fro my work.
  28. zman
    Joined: Apr 2, 2001
    Posts: 16,559

    from Garner, NC

    They won't do it here at all. I asked.
  29. big creep
    Joined: Feb 5, 2008
    Posts: 2,945

    big creep

    nope you are partly correct dont forget the stinger leg! a phase converter is just a glorified capacitor.

  30. If you want to be correct , as I see here, then a glorified capacitor phase converter should be called out as a "static phase converter" of which there are several types and not all phase converters are static.

    A rotory phase Converter is not a glorified capacitor and delivers full power
    However, it uses energy in the process.

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