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Electrical question when doing wrong might be right

Discussion in 'Electronics' started by C4ENG, Jul 11, 2011.

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  1. C4ENG

    C4ENG Senior Member

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    We want to supply power to an electric stove that requires 240V 60hz.

    We know the US single phase 240V 60hz voltage and has L1 and L2 supplying power for the heating element.

    But now you are on a vessel that has 380 three phase 50hz house power. L1 to L2 will give you the 380V. L1 to N will give you 220V.

    Would the 240V US stove heating elements work if L1 is 220V and L2 is neutral?

    This is oppose to L1= 120V and L2=120V for the way it is intended. What will happen?
  2. PropBet

    PropBet Senior Member

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    How are you solving the 50 to 60hz issue?
    (with / if that is solved), no, I'd make 240 through L1 and L2.
    L1 to N will yes, give you 240V however it's half the cycle. So whatever is on the other end won't last long. Let alone a host of other [electrical safety] issues that I'm sure the true electrical experts can elaborate on.
    I believe the only place you can safely do what you're describing is in a 3 phase environment.
  3. K1W1

    K1W1 Senior Member

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    Hi,

    Can you please explain how the frequency (cycles) can be changed by a variation in the voltage? (I am not asking about changing the genset speed)


    There is still going to be the Frequency Issue which will not have much of a problem dealing with the heating loads if it is 50 or 60 cycle the element is just a bit of wire it has no real moving parts other that a few electrons.

    The potential problems come from anything that uses frequency for a rime function - The clock or oven timer and fans in the unit.

    That being said it has been done before and has worked on a simple oven with mechanical controls.
  4. Marmot

    Marmot Senior Member

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    The voltage between any of the 3 legs should be 380. The voltage between any of the legs and neutral should be 220.

    Yes

    You will have a large phase imbalance when the stove is on. This may or may not cause problems elsewhere. K1W1 addressed the other issues regarding timers that use line frequency for clocking.
  5. C4ENG

    C4ENG Senior Member

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    Thank you guys.
    I am in an awkward situation with people buying parts while saying "The salesman said it would work" Of course he did.HA.. and charter guess coming tomorrow and bla bla bla..
  6. C4ENG

    C4ENG Senior Member

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    It did not work. It would just trip the breaker. You need the right tool to do the job right.
  7. K1W1

    K1W1 Senior Member

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    Hi,

    Can you tell us a bit more?

    Were you exceeding the amperage on one leg of the Three Phase Breaker that used to supply the Oven?
  8. jhall767

    jhall767 Senior Member

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    Generally a stove like that is going to have some portion of it (clock, timer etc) that is only 120V. May have shorted out a 120V component. Also you would want to make sure you switched the hot lead to the burner and not the neutral. You'd really need to have a wiring diagram to convert that stove.
  9. Marmot

    Marmot Senior Member

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    Too high a load on a single phase evidently.

    Did the breaker open after turning on more than one burner element? If so you may be able to wye connect each element to a separate phase (4 elements? run the two smallest off the same leg) and prevent the current on a single phase from going sky high and tripping that breaker.
  10. K1W1

    K1W1 Senior Member

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    Hi,

    Or a good test meter and the ability to use one
  11. Marmot

    Marmot Senior Member

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    Good point, a transformer to supply the 120v consumers is required since there is no longer 120v available from line to neutral as in an American 220v supply.

    Personally, I think replacing it with a European 3 phase appliance would be the best idea.
  12. PropBet

    PropBet Senior Member

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    Perhaps my reply was misunderstood. Or not descriptive enough.
    For a heating element, I don't think that 50hz to 60hz would be a deal breaker. Nichrome with current fed to it, be it 50hz or 60hz will heat up (resistance) the same.

    Changing the frequency from 50hz to 60hz is a larger project, as I'm sure you know. This obviously is mutually exclusive to voltage. No relation or affect from one to the other.
  13. C4ENG

    C4ENG Senior Member

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    Here is what happened. It wasn't really a stove but a deep fat fryer that the chef ordered. I hard wired it from the breaker with the one leg of 220V and the N. I filled the fryer with water for a test run. The fryer came on and heated the water to temp and quite quickly. Then when the thermostat was satisfied and went to open the contactor to turn off the heat, that would trip the breaker. I then tried switching the one hot leg of 220V to the other side of the L1L2 to see if that would make a difference but it did the same thing. There was a transformer inside for the contactor and I think that was the issue tripping the breaker. It certainly heated the elements just fine.
  14. Marmot

    Marmot Senior Member

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    Can you post the make and model of that unit so we can look at the circuit diagram?

    Most appliances have a diagram pasted to an access panel so you might have it available anyway.
  15. C4ENG

    C4ENG Senior Member

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  16. Capt J

    Capt J Senior Member

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    It should be easy enough to get a commercial fryer that will use 3 phase electric.
  17. K1W1

    K1W1 Senior Member

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    Hi,

    The parts list for that machine doesn't show anything in way of a transformer.

    If the timer is mechanical and the thermostat is only used to control the contactor coil you should be able to use that no sweat on 240/ 50.

    What is the rating of the breaker you are using to supply it and what is the style of breaker?
  18. C4ENG

    C4ENG Senior Member

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    K1 You hit the nail on the head. As I was taking this wiring picture I saw that it was a 6000 Watt fryer. 6000 / 240 = 25 Amps. The breaker used was a 10 Amp that fed a salamander. It lasted just long enough to heat up the water causing me to think the T Stat was satisfied before popping..

    Attached Files:

  19. DON GREER

    DON GREER Member

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    DO NOT CONNECT a hot line L1 and neutral in a heating element circuit. The element acts as a loop and will result in voltage on the neutral everywhere in the boat where the neutral is also connected. The 50 Hz and 60 Hz is not really an issue for a heating element especially as such an element is thermostat controlled. Get an auto transformer 380 primary / 240 secondary; using L1 and L2 as the primary the output from the auto transformer will deliver the 240 you desire. As such the desired heat can be attained despite the Hz issue. In the day I have wound these transformers. They are not expensive. Good luck.