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220 wiring alternative

Discussion in 'Woodturning Discussion Forum' started by Nick Boyd, Jan 3, 2018.

  1. Nick Boyd

    Nick Boyd

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    just want to say - I have been turning on my woodfast 910 vs 1.5 forever using a transformer 110>220 as a solution to not having 220 wiring which would cost way more, way more to get installed or downright impossible in some cases - flawlessly. I keep seeing some using not having 220 to connect to during their quest to get a lathe.
     
  2. Fadi Zeidan

    Fadi Zeidan

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    Thanks Nick. I’d love to hear from the electrical engineers and equivalent on this forum.
     
  3. Bill Boehme

    Bill Boehme Administrator Staff Member

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    OK, I bought a couple unused Square-D Isolation/Step-Up/Down transformers on eBay a few years ago with the purpose of converting 240 VAC to 480 VAC in order to use them to power a Baldor industrial inverter. I never got around to finishing that project because I found a better alternative ... a Robust American Beauty.

    The transformers were designed for resistive loads (lighting, televisions, computers, ovens, etc.) and would have to be derated for reactive loads such as motors. I'm not quite sure what the impedance of the inverter and motor would look like as viewed from the transformer, but it might be an interesting lab experiment.
     
  4. Nick Boyd

    Nick Boyd

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    I can’t tell what that response is saying - it seemed simple to me. I bought the correct size 110>220 step-up transformer given my lathe’s needs - they make these for lots of applications and it worked fine from 1996 until 2010 when i finally hooked my lathe up to a 220 circuit and I noticed no difference in power, sound, etc. It was a solution to a problem when I wanted more punch than a 110 volt motor offered.
     
  5. Fadi Zeidan

    Fadi Zeidan

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    Sorry about that, the reason I’m looking for more feedback because I’m interested in 2HP lathe and this would be the perfect fix if it works.

    I found this discussion and the answers are mostly yes it may work for 2HP, but with some arguments that I’m not qualified to dissect.

    http://www.practicalmachinist.com/v...onverters-and-vfd/step-up-transformer-198953/
     
  6. Hy Tran

    Hy Tran

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    Disclaimer: Use what I state here as "educated opinion" and NOT AS PROFESSIONAL ADVICE.

    If you have a 2HP lathe, that's about 1500 W at the shaft. Accounting for inefficiencies, that's more like 2000 W electric.

    1 W is not equal to 1 VA (power factor, which we will minimally discuss). But for rules of thumbs, with a good modern controller that uses vector control (don't ask, seriously), the vector drive looks very much like a resistive load (like an incandescent bulb) to the power line, in other words, a power factor close to 1. Older drives will have a power factor much less than 1. As a rule of thumb, at a power factor of 0.5, 1 W requires 2 VA.

    It is very likely that your lathe will not show a power factor number anywhere, but you can make a good guess based on the voltage and current rating of the lathe on a plate stamped near the motor or controller.

    I suspect that the Robust AB uses a (purchased) vector drive; ditto Powermatics. I would look at the lathe's electrical rating plate, which will list maximum current draw. Multiply that by the voltage rating to get a VA number (e.g. if the lathe says 10A, 220V, 10x220=2200 VA, so you need a transformer good for 2.2 kVA. Don't get the 2 kVA, go next size up, which is likely 2.5 kVA). The 10A is a peak value--the lathe won't be drawing 10A most of the time--only during times of high power (accelerating a large rotating mass, etc.).

    Almost finally: If your lathe is (using my example) a 2HP lathe, with 10A/220V on the plate, that means that effectively, you should connect to a 20A circuit at 110V (practically the same VA at 110V or 220V). Most household circuits are 15A (the outlets, anyway, even if the circuit breaker in the panel is 20A). Some outlet receptacles may not be compatible with a 20A plug (1 horizontal blade, 1 vertical blade, round prong).

    A 2 or 3 kVA step up transformer runs roughly $200 to $300. I bet that if you have your house's electrical panel in the garage, an electrician could wire up a 220V outlet from your electrical panel (if there's physical room in the panel) for 2 hrs of labor + parts.

    Your house also almost certainly has a 220V outlet in the laundry room. Think about just putting the lathe in the laundry room, and doing away with the clothes dryer--after all, what's more important? Dry clothes, or turning happiness?

    Best,

    Hy
     
  7. Nick Boyd

    Nick Boyd

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    No problem i am curious too as to relevent issues that may be offered - not theory but definitive conclusions if they prove I should have not done it
     
  8. Bill Boehme

    Bill Boehme Administrator Staff Member

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    OK, in layman terms it appears that you were lucky or very conservative in your transformer selection At least nothing burned up, but depending on the transformer, the lathe motor may not be able to output it's rated horsepower. But, it runs and if you're satisfied then that's all that matters.

    The word theory or theorem can have different meanings dependant upon whether you're an engineer or a lay person. To an engineer, a theorem is definitive. To a lay person there might be a connotation of speculation.

    I agree with Hy that it is rare these days to find a house that doesn't already have 240 volt service. Essential appliances like clothes dryers, ovens, cook tops, HVAC systems, and of course larger woodturning lathes all run on 240 volts.

    To Hy, despite the words used in advertising, no woodturning lathe uses real vector drive, but several of the high end lathes have inverters with "sensorless" vector drive ... sort of an oxymoron. The project that I never finished did have an optical encoder feedback to give true vector control. Surprisingly, the Powermatic lathes, even the newest models still use simple V/Hz control algorithms.

    I suspect that you are right about the power faction when an inverter is used..
     
  9. Nick Boyd

    Nick Boyd

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    In my case I was renting a carriage house in the historic district of Fort Wayne In. No 220 was available without more substantial cost or at all - there r others out there with the same sort of issue - but perhaps they don’t need to settle for less.
     
  10. Nick Boyd

    Nick Boyd

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    Not luck - I just made sure I got the correct transformer and the circuits I used were 20 amp when 220 was not available for whatever reason. It ran at its intended hp - I dont know why the need to imply anything might have been compromised.
     
  11. Andy Chen

    Andy Chen

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    Evidently, with some lathe design, the motor is 3-phase. The speed regulator actually inverts you single phase line power to 3-phase. I have no idea how step-up transformers work. I have had an old Oneway 1018 that has a mere 1-hp motor but was wired for 240 v. I don't have any problem in my shop but occasionally I take it on the road for demos where there are no 240 outlets. A couple of years ago I bought a 120 v to 240 v converter (transformer?) from Oneway. Guess what? I was intrigued that the output was not only 240 v but is also DC not AC. This is way beyond my understanding.

    BTW, installing 240 outlets is not that big a deal. All you need is a little basic knowledge and a LOT care/caution. If you have a couple of spare slots in your breaker box you can do it.

    Bill Boehme, do you ever sleep?
     
  12. charlie knighton

    charlie knighton

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    Superhero Powers
     
  13. hockenbery

    hockenbery AAW Advisor Staff Member

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    All you really need are two independent 110 lines to make a 220.
    the Tricounty woodturners use this to make a 220 and the Florida Symposium do it for their demo rooms.

    Not sure what is in the box but two 110 cords plug into the separate circuits and the lathe plugs into the box.
     
  14. Dennis J Gooding

    Dennis J Gooding

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    Al, that works only if the two 120 V circuits come from opposite phases of the 220 V service.
     
  15. Nick Boyd

    Nick Boyd

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    Yes, not just two separate circuits
     
  16. Nick Boyd

    Nick Boyd

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    wait - is this what a 220 breaker does? Grab two different sides of panel?
     
  17. Dennis J Gooding

    Dennis J Gooding

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    I believe that Hy has pretty well summarized the technical aspects of the problem. My conclusion is that you would be operating near the edge of practicality and while it has worked to personal satisfaction in at least a few instances with a "2 HP" motor. It may not meet the needs of other, more aggressive, turners or with other "2 HP" motors. I put 2 HP in quotes, because there can be a vast difference between engineering department HP and marketing department HP.
     
  18. Dennis J Gooding

    Dennis J Gooding

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    Yep.
     
  19. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I have some heartburn about wiring kludges such as that. Using it as a expedient workaround for something like a club demo has the potential drawback of teaching someone who lacks sufficient wiring knowledge the wrong way to do it. The problem is that this is using two separate circuit breakers that aren't ganged together. So, if there is a fault condition only one of the breakers would trip leaving live voltage still present on the machine even though it can't run. I have been in the shop of a friend where this was his permanent wiring solution for having 240 volts for his lathe. To make matters more scary, he was using a 125 volt 20 Amp wall receptacle (NEMA 5-20R) rather than a 250 volt 20 Amp receptacle (NEMA 6-20R). The difference is that the horizontal blade is on the opposite side and the problem is that a 120 volt plug could be inserted into the socket with disastrous results. While I was trying to convince my friend that his wiring job was unsafe, he was telling me that it works. And, he was absolutely certain that I was mistaken about the wall receptacle. :D
     
    hockenbery likes this.
  20. Nick Boyd

    Nick Boyd

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    I do not know why so say that "operating on the edge......" a proper converting transformer 110 to 220 can be bought and for any HP
     

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