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motor and pumps use 2 x 115 v ac and this is problem

Discussion in 'Sensors and Actuators' started by christos, Sep 9, 2015.

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  1. christos

    christos

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    Sep 9, 2015
    Hi , i have bought a machine from USA that has some motors and pumps. All of them use 230 vac to work . As i saw at the manual they take 2 phases 115 vac each without neutral . In Greece i am now we have main power 230 vac . Is there any way to manage to use this power instead of using a transformer ? (the transformer i beleive it will have input 230 vac and a neutral and output 2 x 115 vac and neutral . In other words , is there any way to use 230 vac and neutral to make the machine work ? Sorry for my poor English and you must know i do not know many things about these .

    Thanks a lot
     
  2. BobK

    BobK

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    Jan 5, 2010
    The two phases in U.S. 230V are really not phases, they are 180 degrees, i.e. inverted from each other. When you place a device across the two "phases" it is equivalent to a 230V single phase system. You can use your 230V single phase power to directly power this.

    Bob
     
    Minder likes this.
  3. Minder

    Minder

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    Apr 24, 2015
    I agree they should work, N.A. is 60Hz 240vac 1ph with centre tap for 120v, don't you have 50Hz in greece?
    If so the motors if induction type will run a little slower, and could run at a slightly higher temp.
    Something you may want to monitor.
    M.
     
    Last edited: Sep 9, 2015
  4. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Yes, but there may be 115v circuits on this machine where you would need the neutral connection. Also running at 50hz may cause motors and such to run slower.
    A mid tap neutral is often called a "split phase" not 2 phase.
     
  5. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Sorry for redundancy, I'm slow at the keyboard.
     
  6. christos

    christos

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    Sep 9, 2015
    Fist of all thank you very much for your replies . So , as i understood instead of using 2 x 115 vac i can use 1 phase 230 vac and neutral , right ? The connection inside the motors should be the same ? About the 50HZ i beleive it will not be such a problem . There are 115 volt circuits but it will be much easier to use a transformer for these . I post some photos of the motors , pumps and a heater i want to use .Thank you
     

    Attached Files:

  7. Old Steve

    Old Steve

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    Jul 23, 2015
    It's clearly stated on the labels that 230VAC is OK. No transformer needed. Just wire them according to the diagrams on the labels. The only issue is the 50Hz. You might get overheating. When you run them, keep an eye on the temperature at first. Edit: As pointed out by Minder.

    Note that the heater will draw in excess of 20A per element, too. Can your supply provide that OK? How many elements? (It doesn't say on the label shown.)
     
  8. christos

    christos

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    Sep 9, 2015
    All the system is a water treadmill (i post a photo) . The diagram do not say how to connect a single phase of 230 vac and a neutral (only with 115vac uses neutral) but i beleive i will use the diagram that uses 2 x 115 vac and instead of 2 x 115 i will use 230 and neutral . About the heater i will check it but as i read from the manual all the system needs 45A and my main power is 65A . The temperature will be a problem as you say , so as a solution i could use some extra air on them ?
    Thanks
     

    Attached Files:

  9. Old Steve

    Old Steve

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    Jul 23, 2015
    Doesn't 230VAC single phase imply only 2 wires, an active and a neutral?
    (Three-phase has a neutral connection, single-phase doesn't.)
    Or perhaps I'm not understanding you properly.

    Yes, that would help if it was needed. See how you go. May not be necessary.
     
  10. christos

    christos

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    Sep 9, 2015
    My main power has 230vac single phase and a neutral , 2 wires (and of cource the earth line) . In USA as i understand if you want to use 230 you have 2 wires of 115 vac and you use them without neutral and a neutral if you need to use it to a 115 vac circuit . So the machine has 4 wires at the main cable ( 2 x 115 , neutral , earth line) . In Greece we have 3 wires ( 230 vac , neutral , earth line) .
     
  11. Old Steve

    Old Steve

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    Jul 23, 2015
    Yes, that's what I thought. It's the same here in Australia - 240VAC, single phase, 50Hz, with active, neutral and earth wires.
    The earth is for safety only, not for connection to the motor terminals. It should be attached to the case of the motor.
    All you need, for the motor terminal connections, is the active and the neutral, as shown on the motor labels. You're good-to-go, as they say.

    In the first of the motor labels you posted, there are two diagrams. Use the bottom one. Connect your 240VAC 'active' wire to one, and the 240VAC 'neutral' wire to the other. Then, for safety, connect the earth wire to the case.

    N.B. The label says "Line' 'Line', but for you and I, that equates to 'Active' 'Neutral'. Do you understand now? (Active and Neutral are the two 'Line' wires.)
     
  12. christos

    christos

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    Sep 9, 2015
    I will try it and i will inform you . Thank you so much
     
  13. Minder

    Minder

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    Apr 24, 2015
    If you have line and neutral it should not matter which line you connect the neutral to.
    In N.A. the unit would only have three supply lines also but 2 (240v) live conductors and a earth ground.
    In your situation the unit will see 1 live and 1 neutral (240v) this will appear the same AFA the unit is concerned.
    M.
     
  14. Old Steve

    Old Steve

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    Jul 23, 2015
    Isn't that what I said? I thought I explained it pretty clearly.
    And you might confuse him more, mentioning 3 supply lines, especially if he doesn't realise what NA refers to. I had to think for a bit.
     
  15. Minder

    Minder

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    Apr 24, 2015
    I only meant to point out to him and try to explain the meaning of the neutral as he appeared to be getting a little confused about 4 conductor that can be used in US/CAN.
    It was intended to re-enforce your comments not override them.
    Poster here seem a little more touchy than other forums, it is the second 'rebuke' if this nature I got this week!!!o_O
    M.
     
  16. Old Steve

    Old Steve

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    Jul 23, 2015
    Sorry. I didn't mean to offend. I'm a bit blunt sometimes, but just ignore it.

    I just thought that you might confuse him more with the 3-wire reference. He seemed to be having a great deal of trouble understanding, possibly due to language difficulties.
     
  17. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    People often throw out the term "neutral" with single phase (2 wire) incorrectly.
    A neutral is the conductor the carries the unbalanced current between phase conductors.
    Single phase (2 wire) has a grounded conductor. White in US, or blue in EU.
    It is not a true neutral.
     
  18. Old Steve

    Old Steve

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    Jul 23, 2015
    In Australia, the two wires are known as 'active' and 'neutral'. These are the correct terms here. (And in the OP's country, Greece, as far as I know.)
    I'm not just incorrectly "throwing out the term" at all, as you so bluntly put it.

    The term 'neutral' here is derived from the fact that the neutral wire is connected to the true neutral in the 3-phase 415VAC source.

    And no-one said that the neutral is ground, as far as I can see.
     
    Last edited: Sep 10, 2015
  19. Old Steve

    Old Steve

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    Jul 23, 2015
    Here's a diagram of what I'm talking about:-

    415-240V.gif
     
  20. Minder

    Minder

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    Apr 24, 2015
    The term neutral may not be strictly an exact quotation but it is a term that is has been customarily used by most of the world to indicate a grounded conductor quoted in N.A. by NEC/CEC/NFPA79.
    e.g. in N.A. If a piece of equipment uses a 3ph 480v/600v transformer with a 120v secondary for control purposes, it is allowed to set up a local 'neutral' by earth grounding one of the secondary conductors, this then is termed neutral.
    In other parts of the world a Neutral often refers to the star point of a 3phase transformer which is then earthed.
    My electrical qualifications were actually obtained in the UK, where the term neutral has also been used as far as I can remember.
    My beef in N.A. is the term ground is used for both chassis or frame ground And Earth ground.
    Rather than as in U.K. Earth and Ground may be two distinct descriptions and the two symbols correctly used, rather than the way they are misused in N.A.
    M..
     
    Old Steve likes this.
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