Register now to get rid of these ads!

Any 3 phase electric guys on here?

Discussion in 'The Hokey Ass Message Board' started by Willy301, Mar 24, 2012.

  1. Willy301
    Joined: Nov 16, 2007
    Posts: 1,426

    Willy301
    Member

    Run a common white wire to what connections? Three phase doesn't normally have a common wire....
     
  2. Willy301
    Joined: Nov 16, 2007
    Posts: 1,426

    Willy301
    Member


    If I did this, I would put a 220 motor on it, but how do I get a 220 motor with all the correct mounting flanges, or do I need to adapt something?
     
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 47,791

    squirrel
    Member

    That's usually the tough part, finding a single phase motor that is relatively easy to adapt to a mill. That's why the VFDs are becoming so common.
     
  4. Wow, ain't seen one of those in years. One shop I worked in had a bank of them, all in tip-top shape. Hardinge also made something real similar.

    Bob
     
  5. I would go 220 myself. But do you still have the instant-reverse capability? Kind of essential for power tapping and running in back gear.

    Bob
     
  6. 28pontiac
    Joined: Nov 14, 2003
    Posts: 192

    28pontiac
    Member

    I have a WEG VFD I have used for several years... Much easier than anything else. I think I bought it at M & R Electric in Dayton for $150. For a home hobbyist, this was the cheapest easiest way I found.
     
  7. Truckedup
    Joined: Jul 25, 2006
    Posts: 3,964

    Truckedup
    Member

    Residential single phase house current is 240 volts in 99 percent of the country,220 volts is long gone.if the machine has a non geared reverse using a switch to swap motor leads to reverse direction,a non three phase motor will require some rewiring.
    I've seen simple solid state phase converters the size of a man's fist run a 1-1/2 HP three phase mill.
    Converters aren't a substitute for a three phase electrical service in heavy duty situations.But they work quite nicely in a small shop.
    For an example to compare to the cost of phase converters,I'm an semi retired electrical contractor in Western NY state...A new 200 amp three phase overhead service is about 3000 bucks.that would be a new 42 space panel with main breaker,metering,grounding,necessary wiring to the utility co attachment on the building,reasonable priced permits and or inspection if required.This situation would be for a replacement on an existing single phase service or new work.Obviously if the building wiring is all fucked up the price is higher.
     
  8. squirrel
    Joined: Sep 23, 2004
    Posts: 47,791

    squirrel
    Member

    And that's in an industrial area where there is 3 phase available, right? I know a couple guys who were setting up shops in "industrial areas" and they couldn't get 3 phase service from the electric company.
     
  9. Truckedup
    Joined: Jul 25, 2006
    Posts: 3,964

    Truckedup
    Member

    Yes,where's it's available.And that depends on you or your contractor's "pull" with the utility company.Generally speaking if there's overhead wiring ,and you see three wires at the top ,it's three phase.Same goes for underground only you can't see it ,lol.The utility company may allow it or not depending on many factors including politics.And usually at the minimum,a 300 buck one time hook up charge.If they have to install transformers ,you will get charged for that,in the range of 800-1800 bucks.
    I would say if your friend's are in an industrial area with readily available three phase and they can't get it,they aren't speaking to the right people.
     
  10. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 5,408

    Ebbsspeed
    ALLIANCE MEMBER

    No brushes in a 3-phase motor. It uses a "rotating" magnetic field created by the three phases to move the armature
     
  11. MeanGene427
    Joined: Dec 15, 2010
    Posts: 1,584

    MeanGene427
    Member
    from Napa

    I have two of the simple $75 Anderson static converters, one on the Bridgeport and one on the 16x60 South Bend, both have their original 3ph motors, and have never been short of power on either one- how often do you make that big of a cut to need "full" power? If one ever goes bad, I would probably try the VFD setup- but I wouldn't change just for the halibut
     
  12. Dawai
    Joined: Oct 1, 2007
    Posts: 263

    Dawai
    Member
    from North Ga.

    30 plus years of electrical experience, 3phase, industrial, plcs & automation.
    Welcome to call me.. pm for number. I can talk you through this.

    It's ain't rocket science. I second on the single-phase in-three phase out inverters thou.. a good 2hp will set you back a couple of hundred, that plus the reduction in the top end will make excellent speed control.

    Mine runs just fine, it's a old cnc converted from paper tape to PC. When you can keep the mice outa it..
     
  13. Willy, probably have done this but I haven't seen it mentioned.
    Check that your motor is wired for the voltage you are feeding it.
    Most of the 3 phase motors are capable of running on multiple voltages, depends on the orientations of the nine wires. Should be under the connection cap.
     
  14. Dawai
    Joined: Oct 1, 2007
    Posts: 263

    Dawai
    Member
    from North Ga.

    Common 9 wire connections for 240 volt 3 phase.

    1 & 7 line a in
    2 & 8 line b in
    3 & 9 line c in
    4,5,6 tied together.

    Some bridgeports are 12 lead motors, I'd have to look in the book..
     
  15. 1967gtafb
    Joined: Mar 22, 2012
    Posts: 41

    1967gtafb
    Member

  16. cjsavage
    Joined: Oct 28, 2011
    Posts: 57

    cjsavage
    Member
    from eastern nc

    I have a 3HP manual lathe and 2HP manual mill running off the same 6HP factory made rotary phase converter. No problems in over 35 years. Cost $500.00 35 years ago. Have a 7.5HP CNC lathe running on a homemade 10HP rotary. Have a 20HP T-20 Cincinnatti Milacron machining center running on a 20HP homemade rotary. Have a 2HP CNC Bridgeport running just the spindle on a 3HP Variable Frequency Drive. As said before, the VFD is the way to go on smaller stuff, forward, reverse, variable speed, $150 is what I paid for my 3HP VFD. If my 6HP failed, I would replace it with 2 VFD's. Go to cnczone.com for info on all things machining, rotaries, VFD's, etc. Great site.
     
  17. Truckedup
    Joined: Jul 25, 2006
    Posts: 3,964

    Truckedup
    Member

    cjsavage says;
    Interesting,how much amperage does that set draw and what amps is your electrical service?
     
  18. cjsavage
    Joined: Oct 28, 2011
    Posts: 57

    cjsavage
    Member
    from eastern nc

    200 amp service. Not sure of the draw.
     
  19. cabriolethiboy
    Joined: Jun 16, 2002
    Posts: 872

    cabriolethiboy
    Member


    Did you get the one at the auction in Alexandria, Indiana?
     
  20. '51 Norm
    Joined: Dec 6, 2010
    Posts: 722

    '51 Norm
    Member
    from colorado

    I just had to weigh in on this one.

    First my credentials; I have been an industrial electrician at a power plant for 30+ years. I also play with old three phase machine tools.

    The first machine I had came with a static converter. It worked well the whole time that I owned the Machine. Static converters make what I refer to as "pretend" 3 phase by shifting one of the phases about 90 degrees. It is a little complicated to explain but the result is that the motor develops about 2/3 power; plenty for most applications.

    When I got my second machine I had been reading all of the articles on rotary phase converters and so I built one. It didn't work worth squat; having about the same problems that you describe. Eventually I determined that the cause was the reactive power draw in the system. Please don't have me try to explain the difference between reactive and real power. With some fussing with the capacitors and inductors I managed to get the rotary converter to work but it isn't something that I would recommend. I donated that converter to the new owner when I sold the machine.

    My current machines use a VFD and I believe that is the way to go.

    What hasn't been mentioned is that the VFD will need to be rated about 1/3 higher that what the motor on the machine is rated. This is because the VFD doesn't make any power; it just changes it. You can't get something for nothing and so the single phase input will draw more current in than the three phase going out. This usually isn't a problem unless you are working with motors over three horsepower.

    Most manufacturers of VFDs will address the phase converter rating somewhere in the manual that no one reads.

    The additional benefit of variable speed, motor overload protection, dynamic braking, soft start capability and easy reversing are icing on the cake.

    As has been mentioned CNC zone has a wealth of information on all three types of phase converters. Home Shop Machinist magazine is also a good resource.

    My latest machine tool project is to change the control system on my CNC mill, again. The current system works lots better than the old one but being a hot rodder at heart I just can't seem to let well enough alone! Some day I may even make some parts.

    Good luck with your project.
     
  21. ems customer service
    Joined: Nov 15, 2006
    Posts: 2,570

    ems customer service
    Member

    most bridgeport parts are the same, everything is a copy of the orginail bridgeport,

    but you could start with a electric motor repar shop they may sell it or direct you to a seller
     
  22. Willy301
    Joined: Nov 16, 2007
    Posts: 1,426

    Willy301
    Member

    There is one shop, and it is probably about a half mile by the way the wire would have to run...and was told that 3 phase would never be hooked to my home hobbyist shop, but if it were even a possability, I would have to buy every inch of wire, and pay the hourly rate for the crew to run the line and hook it in, on top of paying for the actual additional pole requirements and additional transformers.....I don't forsee this even being a possability, I already have a second mortgage:D
     
  23. Willy301
    Joined: Nov 16, 2007
    Posts: 1,426

    Willy301
    Member

    I am having a problem, that is kinda the point. And like I said before, if I had a 1.5 hp, I would not sweat it either, but a "big cut" to a 1.5 hp is a lot different than a "big cut" on a 3/4 hp....Considering the cuts I already made causing this issue, I have not even seen a "big cut" yet.... Static is not the answer to my problem...
     
  24. Willy301
    Joined: Nov 16, 2007
    Posts: 1,426

    Willy301
    Member

    I am actually not too far from Dayton, and 150-200 sounds like it is very reasonable. I will have to see if they are still in business, and still have them at a good price...or see if something in Columbus might be available... Thanks
     
  25. Willy301
    Joined: Nov 16, 2007
    Posts: 1,426

    Willy301
    Member

    Well Vicky, I can only say that the electrician that was actually supervising the project, did know his stuff about the voltage, and I am pretty sure he took that into account. Although, he was an old guy, and the whole "phase converter" thing had him a little flustered. He did have all the info I had compiled, in front of him, and he did seem to study it at great length before we did anything, and several other times throughout the process....

    The whole plan came about when a freind turned me on to a 5hp 3ph table saw that was about to be scrapped... It had the static phase coverter with it, and we wired it exactly as it was when we took it out of the place....after we disassembled the saw and recovered from the hernia caused by almost every piece of it.... I will say I did pretty well at scrap yard, recovering my cost of the saw, and then some...the saw itself was not saveable, it looked like a building had collapsed on it, but the motor runs as smooth as butter, and is quieter than any motor I have ever heard. Was thinking about mounting a buffer or something on the shaft, so it could be useful as well, but the shaft is close to 2"....
     
  26. Willy301
    Joined: Nov 16, 2007
    Posts: 1,426

    Willy301
    Member

    No, I bought it about 3 years ago out of Cleveland area of Ohio...
     
  27. If you got it from HGR, there is a possibility that something was wrong with it.

    I'm not an electrician, but I have 3 phase and I manage to get this old equipment going and have made some rotary converters before. With that said......
    If you have a static converter that runs your 5 HP 3phase, why not just have that static converter run the mill?
    The rotary versions that I have experience with were powered with single phase to generate 3 phase. Your system, if I'm understanding it correctly has too many components.
    The first part is static to 3ph which gives you a known power loss. That's trying to run a 5hp 3ph motor.
    Then you have 3ph to 3ph which gives you another drop of which I have zero idea. That out put (double dropped) is trying to run your mill.
     
    Last edited: Mar 27, 2012
  28. Truckedup
    Joined: Jul 25, 2006
    Posts: 3,964

    Truckedup
    Member

    Static converters do not really generate 3 phase.They simulate three phase for a brief time to get the motor started,then the motor runs on what electrician's call "single phasing". This means a three phase motor will run at reduced power on single phase once it get started.This will work ok for machines without a huge starting or running load such as compressors.
    All electric motors use an inrush of current when starting.On a compressor this might be 2-3 times the running amps for a few seconds.For example a typical 7-1/2 HP 240 volt single phase compressor has an inrush of 80 amps or so for a few seconds,then a running amp draw of around 35-40. A three phase 230 volt 7-1/2 motor has a running current of 22 amps,inrush of about 45 amps...But on the line side of the converter where the single phase is fed into,the amp draw is closer to a similar HP single phase.
    Usually all is fine,but if the motor locks up during starting or running ,the amps can increase many times before the over current device opens the circuit.Many installations I've seen lack the proper overload devices and this can blow the utility company line fuse.That mean the power goes out for you and maybe a few neighbors requiring a lineman to restore power.Power companies frown on phase converters for the above reasons.If you read their regulations it generally written they require you to notify them is using a motor in excess of 7-1/2 HP on a single phase 200 amp service.I'm a listed sub contractor for the local utility company so I'm aware of potential problems from poor engineered installations.
    Do it right and you shouldn't have any problems....Of course as a contractor I make money on installing three phase services,so I might be slightly bias :D
     
  29. Willy301
    Joined: Nov 16, 2007
    Posts: 1,426

    Willy301
    Member

    Vicky, while the static phase converter will work, it reduces the mill operating capacity by 1/3 hp. If I had a 1.5 hp, that would not be significant to me. But it is only 3/4 horsepower and taking it down to 1/2 would eliminate a lot of tasks that would make the mill handy to begin with. We wired this up following a diagram that was published by a certified electrician, but not one that I know, or can talk to, to determine my problem. This is actually setup as a Hybrid rotary phase converter. I actually thought it would be easier than a true rotary phase converter, but it is turning out to not be the case. In any event, I may need to either make it a true rotary or just get the VFD unit. I am researching price, availability and suitability of the VFDs now... I will update this if I make a decision, or if I need to ask more questions about making the rotary...If I buy the VFD, I will probably sell the 5 hp motor because it is just too heavy to have laying around. I would likely sell the static unit as well, it is just a small aluminum box that is screwed to the wall... I had a 3 phase lathe before this, and we used a bunch of capacitors to make a static phase converter for it, and when I had trouble with it, a 220 single phase lathe became available to me, so I just sold the larger lather to pay for the smaller one...The first one was 8 foot centers and had a 4 speed transmission hooked to the motor, I should have kept it and put a Hemi on it and made it portable:D.

    I appreciate all the responses and some really good info here, as I had not even heard of the VFD prior to posting this...Now to get past the tooling issues, as this is not a morse taper, but a 3/4 straight quill....I have some inserts to fit some tooling, but I need to make a bigger variety to fit more tooling....
     
  30. ems customer service
    Joined: Nov 15, 2006
    Posts: 2,570

    ems customer service
    Member

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.