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Technical Phase converters, one big rotary converter or repower the equipment ?

Discussion in 'The Hokey Ass Message Board' started by 31Vicky with a hemi, Nov 21, 2018.

  1. Not sure what would be the best thing to do since the new place doesn't have 3 phase power.
    My air compressors are 3 phase, my disc sander is 3 phase, my pedestal grinder is 3PH, my buffer and big reciprocating machine is 3ph as well.

    The disc sander gets used everyday and easiest and cheapest to repower. The air compressor with a repower would give up a good donor for 1/2 of a site built rotary converter I think ?? Use one converter to power the other stuff that needs a converter. I can't ever remember using all of it at once either. Maybe each one should get its own VDF ?

    Not sure how to handle this so looking for some input
    Thanks .
  2. i bought one static phase convertor for the two machines i have. the "plus" was it was cheap, the "minus" there is a 1/3 power lose [don't notice] and i have to swop plugs when i use the other tool [p.i.t.a.].
    Joined: Jun 3, 2005
    Posts: 8,210


    For me, at home, I had a whopper of an air compressor. 10HP, 35 CFM@150. Had 200 gal total tank volume too. In order to save $$$ I decided to just buy a 10HP 1 PH motor. Selling it didn't make sense, convertor to run even close efficency was $1,200. I went to Grainger and picked a farm duty that was a direct fit and asked the counter man to discount it as far as he could and still keep his job. Now this was a few years ago (2005) but I walked out tax and all less than $650. So now with 2 motors (it's back in shop duty on 3PH) I have a grand total investment in it of less than $1,500. On single it ran just under 7min to fill both tanks from empty, ran 1 min 18 sec to cycle. It's just a few seconds faster on 3 PH.

    Some machines don't mind the idler motor power drop gig but I didn't want that for a compressor. 5HP motors are pretty costly too. You may need to "pick your battles" on that score Vic. 3PH is cheaper to run as you already know, but a ph covertor can suck up a lot of energy. I only had 1 worry/solution. It pays to ask for deals;)
  4. continentaljohn
    Joined: Jul 24, 2002
    Posts: 4,837


    I run a static phase converter for my Bridgeport mill and Sheldon lathe . I only run one at a time and don’t have any issues . I also have another for my bandsaw and surface grinder and something no issues. I have a buddy that runs a CNC milling center but with a rotary converter with no issues. The air compressor depending on the HP maybe a repower. I am in the same place with my compressor newer IR 7 hp with baldor motor running 3 phase . I believe I am just going to buy a new motor single phase.

  5. SeanIUOE150
    Joined: Mar 27, 2018
    Posts: 5

    from Illinois

    On your smaller equipment you could run VFDs. I’ve got a bunch of older three phase woodworking tools that I run off of VFDs and I haven’t had any issues with them.

    They’re Teco FM50’s. Mine are rated for the size of the motor, no oversizing is required with VFDs typically, unless you have a large amp spike on start up. But these can be programmed for a slow ramp up.

    But since you have the air compressor I would just look at American Rotary phase converters and get you shop setup with one of those. It would be cheaper in the long run.

    The guy I bought my drill press from had an American Rotary unit that he used to power his planner off of and that was rated for a 30hp motor.
    wraymen and bedwards like this.
  6. oj
    Joined: Jul 27, 2008
    Posts: 6,257


    I bought the rotary phase converter and I see an increase in my electric bill, its an extra 15(?)HP motor running in addition to the load. I don't remember how big mine is, the machine it powers is 10HP so it might be 20HP converter. I sure do see it in the electric bill.
    Noisy sucker too!
  7. GearheadsQCE
    Joined: Mar 23, 2011
    Posts: 2,752

    Alliance Vendor

    Just wondered if you looked into getting 3 phase?
    I couldn’t get it in my shop (residential) but my son has it in his cabinet shop.
    I’d spend the $ if it was available.
    That being said, I have Teco FM 50s for my lathe and mill. They work great.

    Sent from my iPhone using The H.A.M.B. mobile app
  8. Marty Strode
    Joined: Apr 28, 2011
    Posts: 5,807

    Marty Strode

    I have several 3 phase machines, some run off boxes, but my lathe is 10 hp, not sure how it would have worked on a box. This rotary was built out of a 15 hp water pump motor, with a 110 v pony motor. Kinda noisy, but it runs the lathe, and 2 mills, at the same time. IMG_2254.JPG
    Last edited: Nov 21, 2018
  9. 1934coupe
    Joined: Feb 22, 2007
    Posts: 4,506


    It is a lot to consider, like tb says it does work but how many machines can run at the same time? How much power is lost? I was told that you need around a 7 hp rotary converter to run one 5 hp motor. Plus the converters are one more thing you have to deal with. I had a 3Ph. wood planer that I put a converter on (not rotary) but I did not like the extra stuff so I sold the machine and gave the guy the converter with it. He's happy, I'm happy I picked up a single phase 220v planer. The cheapest and easiest way out is not always the best. Choose wisely.

    tb33anda3rd likes this.
  10. Can you get 3 phase power to the building ?

    Do you own the building or are leasing?

    Factor on your total costs to repower and get s converter or vfd.

    3 phase stuff is expensive to buy but cheap when selling it off. As most folks don’t have access to 3 phase power.

    Are you paying the electric bill or the landlord ( if you have one)

    This is a long game play, don’t look at the pennies now if it’s going to cost you dollars in the long run.

    I know your smarter then this and probably already thought of all this but if it were me I would be looking long term as what ever you decide can be a win or a pain in the ass in the long run.

    Good luck !
  11. Having 3-phase brought in (if it's even available) will be pricey. You'll be looking at a complete service change, plus the down time while that's being done. May put you on a different rate schedule with the local utility too. But over the long term, probably the cheapest and best solution. If the utility talks about a VAR meter, look into a capacitor bank to correct power factor, it may save you money over the long term. This could be added later if the expense is too much to swallow all at once.

    I'd also check to make sure your existing service is up to the task if using rotary or static convertors. Those will increase the overall load. Even repowering will increase it, so it's something to check.

    Lots of ways to skin this cat, but they all come with trade-offs...
  12. H380
    Joined: Sep 20, 2015
    Posts: 461

    from Louisiana

    Here IF you have 3 phase available on the pole you need a business licence. Even then it depends on how much electricity you will use as to how much the install will be. Its a min $10K for the 3 transformers to be put on the pole plus the drop to your shop is per foot charge.
  13. That varies by utility. The cheapest conversion would be a 'open delta' that only requires two transformers but many utilities don't like them for various reasons. I know for a fact that you can get 3-phase power into a 'residential' occupancy here (think Bill Gates and Paul Allen) but they're not common.
  14. 3 phase is available but they wanted $6000 to get it over to me including the drop. It's a Co Op utility and brand new to me & I to them. It's agricultural exempt so it's pretty loose. They did set me up with my own transformer and a 200 amp drop for 600 bucks. Told me that transformer would be better for me and my neighbors. I figured that's the way to go for now and if it don't work I'll still be looking at 6gs later down the road .

    I've been blessed finding dirt cheap 3ph equipment, now it's going to cost me something I guess.
    Last edited: Nov 21, 2018
    VANDENPLAS likes this.
  15. In the long run for the lowest utility bills, it'll probably be cheaper to re-power to single phase everything you can, then use VFDs on any you can't.
  16. Boneyard51
    Joined: Dec 10, 2017
    Posts: 4,958


    There are various plans on the net to make your own rotary converter, like Marty showed a few post up. You can connect all your machines to one large converter, the turn on the other 3 phase machines to help “ smooth “ out the converter. Just let them run free.I know it will take more electricity, but unles your running s business, most electrical bill for the hobby shop are not that much to start with.


  17. Ok so you have a price to do it once and forget it.
    Then any other 3 phase stuff you stumble across is fair game
    See it a lot in my line of work 3 phase welders, mills, lathes etc going for great prices used as most businesses want new for the expense and write offs and when it’s old it goes for pennies on the dollar.

    At 6 g’s

    What’s your cost to rework and phase convert your stuff?
    How will it all work together? One thing going at a time? Like was posted everything running all the time ( shit that sounds loud !)

    Do the math, I also know 3 phase is a bit cheaper on the monthly bill compared to 110 or 220 high draw equipment. And
  18. I built a 3 phase rotary converter that handles up to 5hp for my hoist, welder, and plasma cutter. I am not doing commercial work any more, but 15 years ago, when I was thinking of getting 3 phase power, the cost was $4,500 and that cost can only increased since that time. The irony of all this is, that the 3 phase service runs right in front of my shop.
    I am quite happy with my converter and idler setup because I only run one machine at a time. I still can't think of a better way to use the inexpensive, used, three phase equipment, and I know that there are more losses because of the conversion, but I am happy with what I have, and have no regrets about not converting.
    Boneyard51 likes this.
  19. CNC-Dude
    Joined: Nov 23, 2007
    Posts: 943


    I bought a rotary convertor for my big milling machine. It has a 5 horse motor on it, and it was recommended that I step up to a 7HP convertor. No regrets, static convertor do lose some percentage of power over a rotary, and anytime you give up something, it can have negative effects on machine performance. Mine is quite, and you can't hardly hear it running. I have a VFD on my CNC router and its fine for lower HP machines, but the rotary type convertors have been the standard for decades and work great.
  20. Mr48chev
    Joined: Dec 28, 2007
    Posts: 29,183


    Three phase is reasonably readily available around here because of the irrigation pumps on the circles and for a lot of the pumps for wheel lines. It would probably cost that same 6K to run it into my place though.
    Personally I'd have to weigh that outlay against the total cost of conversion for the equipment and be thinking of what equipment I intended to buy in the future. As others said usually you can find 3 phase shop equipment pretty reasonable and have it be better quality to boot as the used market for it isn't that great. My neighbor had his old 3 phase shop compressor for sale at his new shop (newer and bigger compresser) for around 600 bucks and got lookers daily but no takers for over a year until someone showed up who had three phase.
  21. As far as repower goes,
    My compressor is the biggest load and 2nd easiest to do.
    My big reciprocating machine would be the next biggest load, very difficult to repower and doesn't get used daily.
    My disc sander would be the easiest to repower and is used a lot.
    My bead roller would be the next biggest load and a bit more difficult to repower.
    Then my pedistal grinder and buffer would be impossible to repower but not used very much
  22. GuyW
    Joined: Feb 23, 2007
    Posts: 567


    Not too on topic, but this thread reminded me. It used to be that most cities use a Universal Code as the starting point for their local laws, and 0.5 hp was the electric motor limit for residential zones! Just a caution that unhappy but astute neighbors can jack you up over noise and shop equipment.
    31Vicky with a hemi likes this.
  23. my next door neighbor has three phase to power the milking machines............only problem is it is about 3/4 mile away...........
    sounds like you need a couple single phase motors, a couple static converters and a rotary for the recipricating machine.
    31Vicky with a hemi likes this.
  24. You might want to check around with any industrial motor shops in the area and see if the 'difficult' ones could be rewound to single phase.
    31Vicky with a hemi likes this.
  25. Pat Thompson
    Joined: Apr 29, 2012
    Posts: 225

    Pat Thompson

    I start a 10HP 3 Phase motor with a static converter and then run my Bridgeport, 21" Southbend, 20Disc Sander, 24" DISC Sander and my 24" Grob Bandsaw by drawing the 3rd leg off that motor. Been using them for 12 years and have no issues. Those static converters make it hard to tap a blind hole due to not reversing instantly.
    31Vicky with a hemi likes this.
  26. dodgedifferent2
    Joined: Mar 8, 2006
    Posts: 116


    Throw the phase converters in the garbage.

    RIP the three phase motor off machine. Sell it.

    Buy a single phase 220v 2 hp motor and mount on machine Make a coupler for motor to drive shaft.
    Bridgeport is easy for drum switch. Basically mount a drum switch for lathe to get reverse.
    If you can machine or weld the parts by yourself. You may have 200 bucks invested in a 2hp motor. Resale later for next homeshop increases because anyone can plug in a 220v outlet.
    Hnstray and 31Vicky with a hemi like this.
  27. I plan on using a VFD for my three machines. I will install a large rotary switch and only one piece of equipment will be used at a time. This way I wont have to play the plug-unplug game. A static phase converter is much less expensive and is essentially a starter. The motor actually runs on 1 ph after it reaches a certain speed. If you plan on running more than one machine at a time or one with a large motor a rotary converter is the way to go.
    I have also heard that a static conv. can damage welders, battery chargers and electronic motor drives. I have never used one so I have no personal experience.
  28. DDDenny
    Joined: Feb 6, 2015
    Posts: 14,864

    from oregon

    My little experience.
    I bought a new 18x80 lathe in the late 80's for my back yard shop (single phase power), it had a 10 hp 3 phase motor, I got it tooled up and ran out of money (all US made tooling and I like to pay cash).
    I had planned on more machinery in the future with a plan of ultimately getting a rotary phase converter, but figured for the one machine I could get me by with the static unit.
    At the time the price of a rotary phase converter was in the area of $800 so at $175 I'd give the static unit a try. I ended up getting a USA made static converter that, if I remember right, was rated for up to 10 hp.
    Got it wired up during a pretty cold winter period, it took a bit to figure out the "sweet spot" on the static converter dial that it liked to start at so it took a few attemps at initial start up. One night the older neighbor guy noticed the lights on in my shop about the time he and the rest of the neighborhood were running their heaters and cooking dinner.
    Apparently his lights started flickering so he comes over and goes "what the hell are you doing over here, I can't get my oven to stay on.
    Figured this was a good time to ask him if he ever needed something machined to just let me know. It all worked out once I got the sweet spot marked on the dial.
    Last edited: Nov 22, 2018
    Hnstray likes this.
  29. Happydaze
    Joined: Aug 21, 2009
    Posts: 1,134


    I don't know much about electricity. Dunno what a VFD is. I think I've seen a rotary converter is a friends shop somewhere - big noisy box?

    I have a 3ph polisher and bandsaw. The polisher was bought really cheap and I was going to put a 240v (UK) motor in it. That sat for some years! I then decided I needed a bandsaw and managed to find a Startrite (3 wheels) with a gearbox making it suitable for cutting metal without modifications etc. Not sure of the HP, not massive I'm sure, but not tiny either, bit the motor is quite huge (at least 12" diameter), ballbustingly heavy and sounds like an electric train when starting up, so it might be more powerful than I think! Killing 2 birds with one stone I got a digital phase converter for no more than about $200. Works, somehow! Can also be used as a speed controller. Also has a wired on/off/reverse switch which I can move into the workspace, and trip over later. The wrong tool is always the one plugged in - I need the plug to be a bit more accessible - another job for down the line.

    Last edited: Nov 22, 2018
    Hnstray and 31Vicky with a hemi like this.

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