Getting Chinese 240V from US 110V?

Discussion in 'General Electronics Chat' started by jstumbo, Dec 21, 2006.

  1. jstumbo

    Thread Starter New Member

    Dec 21, 2006
    2
    0
    I am in the US. I just bought a machine that was made in China, and it needs 240V power. The power is not like the 240V in the US, where it is a neutral and two power leads out of phase. It is only two wires, one for neutral and one for power (240V because they run 240, not 110V). My question is, using my existing power, 110V, 240V and 3-phase, is there a way to somehow replicate the power setup that they have in China/Europe so that I can have just two wires, and have 240V? I know I can get a step-up power converter, but it would need to be about 10,000 watts, and they are a bit pricey.

    Thanks,
    Jim
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,

    Just use the red and black wires (ignore the white). Make sure your circuit can handle 60 amps, and ground the case. 240 VAC is 240 VAC. The only difference may be in frequency. If they run 50 Hz, then your motors (?) may run fast.
     
  3. jstumbo

    Thread Starter New Member

    Dec 21, 2006
    2
    0
    That is what I was thinking. But my boss got me thinking differently instead of trusting myself. He kept saying that the power (hot) wire needs to be hooked up through a circuit (110V) and the neutral to another, and then the electricity comes through the hot and out the neutral, and if you reversed it and had the other way around, it would fry things. Or in this case if you had both sides hot, that there would not be a way for the electricty to get out. I did not think that he was correct, but needed some confirmation. Maybe if we were running DC, but this is AC.

    Thanks,
    jim
     
  4. wireaddict

    Senior Member

    Nov 1, 2006
    133
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    I think it'll work OK. Just to be safe, get an ohmeter or, better yet, a megger set to 1250 V & make sure the frame of the machine is insulated from the 240 V supply terminals, then, if it's insulated, ground the frame of the machine to the building ground [or neutral if there are only 3 wires].
     
  5. Rperlot

    New Member

    Dec 21, 2006
    1
    0
    The boss is no electrician and is confused about the need for a neutral when running 380v but no neutral if running 220V.
     
  6. m4yh3m

    Senior Member

    Apr 28, 2004
    186
    39
    Please make sure you video tape the entire thing. You might have a popular you-tube video in the making ;)
     
  7. wireaddict

    Senior Member

    Nov 1, 2006
    133
    0
    As an afterthought, possibly not everyone knows what a megger is used for. It is used to test electrical insulation. UL requires that insulation on new equipment be tested at twice the operating voltage+1000 V more in order to be listed with them.
     
  8. alim

    Senior Member

    Dec 27, 2005
    113
    1
    What do you mean by my existing power? your domestic supply should be described as 3-wire 110v- 240v it is a single phase supply,so if you have a240v outllet you are good to go.
     
  9. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    In an ideal building wiring system, voltage between ground and neutral will be zero volts. Both white and green wires are supposed to be at ground potential. (Look at where both white and green wires land in the breaker box.) White is the grounded lead and green is the grounding lead.

    There should be 110vac between white (neutral) and black (hot 1), 110vac between white (neutral) and red (hot 2), and 220vac between black and red.

    Actual measurements may vary slightly due to imbalanced loading of the system.

    http://www.allaboutcircuits.com/vol_2/chpt_10/1.html
     
  10. kielhofer

    New Member

    Dec 24, 2006
    1
    0
    Usually 220 v outlets in europe and asia have the hot at 220 v and a neutral. Basically they are using a 3 phase 4 wire wye configuration where they use the hot and neutral.

    The posibillity exists that the internal neutral of the appliance may be connected to the case, using a 220 v american outlet would put voltage on the case and cause problems.

    They do sell step-up transformers and I would use that approach since you can have more isolation than just plugging into the wall.
     
  11. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    That's where Wireaddict's ohmmeter comes into play!:)
     
  12. Johann

    Senior Member

    Nov 27, 2006
    182
    30
    If you measure with a Megger, as suggested by wireaddict, and find good isolation between either of your machine's hot and neutral conductors tested to the frame, you don't need a step-up transformer. Only if the neutral conductor of your machine is "earthed" (grounded) to the frame or chassis of the machine, will an isolating step-up transformer be needed.;)
     
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