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Can we use earth as neutral?

  1. Oct 4, 2013 #1
    In a power station, the transformer's neutral wire is the same which is connected to earth. My question is if the neutral and the earth is basically the same wire, can we use the earth as our neutral point? i mean will it be a closed circuit where current will flow if we connect our neutral wire to earth??

    SAM_0414.jpg

    Regardless any danger that will occur, i just want to know if the current will flow through the ground or not...
     
  2. jcsd
  3. Oct 4, 2013 #2

    dlgoff

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    Yes. In rural areas with long runs of wire, costs can be lowered by using a single high voltage conductor and the earth as the current return path.


    Swer.gif


    Single wire earth return (SWER)
     
  4. Oct 5, 2013 #3
    The "quality" of your voltage depends on how the transformer is grounded. In a floating neutral point or delta connected secondary a phase-ground connection would not give the same function as a phase-phase connection. But it would still be a potential difference between one phase and ground! That is a fascinating fact! Do you know why?
     
  5. Oct 5, 2013 #4
    thanks for ur reply, my problem is solved
     
  6. Oct 5, 2013 #5
    nope why is it fascinating??
     
  7. Oct 6, 2013 #6
    May I interject here ... in theory yes you can use the earth path as a neutral but in reality doing so if the system isn't specifically designed as such then strapping the return neutral path to earth can be very dangerous...
    Consider a fault condition where the neutral was lost then the earth will become the return path and this could make all earth metal work at mains potential if a incomplete circuit ... lethal to the next joe blogs who might put his hand on the radiator
     
  8. Oct 10, 2013 #7

    psparky

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    Yes, current will flow.

    We obviously go to great lengths to separate ground and neutral in our everyday wiring.
    You might ask the question, will the circuit work if I don't ground it. Yes, it will.
    You might ask the question, what if I just use the ground wire for my nuetral....will it work....yes it will.

    All those conditions will work, just they all break code and can kill in short circuit situations and what not.

    And just because a transformer has it's neutral grounded, that is not an invite to use the ground as neutral. Two return paths is always ideal.

    If you have an ohmeter, stick in it the dirt outside your house. Keep the prongs like 5 feet about. You will probably read a few ohms give or take according to the moisture in your soil. V=IR....so you can guess your voltage drop.
     
  9. Sep 29, 2014 #8
    Hi,

    I am an electrical apprentice currently undergoing studies and we touched on the SWER system today. My question is in regards to how the electrons actually travel back to the distribution source/transformer and not just flow off in another direction. To my knowledge they will follow the path of the least resistance so if no infrastructure or conductive aid is installed to ensure their return what's stopping them from travelling wherever they want? Thanks for your time.

    Regards,

    Kieran.
     
  10. Sep 29, 2014 #9

    psparky

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    They will take the easiest, laziest path back to their source which is typically the secondary of THEIR nearest transformer.
     
  11. Sep 29, 2014 #10

    jim hardy

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    Doesn't KCL tell us that charge MUST get back to where it started from?

    What would happen to the transformer winding if its charge flowing out one end didn't come back into the other ?

    "Ground" is widely misunderstood. It's best thought of as "just another wire" , one that goes everyplace on earth.
     
  12. Sep 29, 2014 #11

    sophiecentaur

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    I really don't think bringing electrons into this is of any help to understanding. For a start, with AC, there is no net flow (i.e. they all end up where they started at the end of every cycle) and also, you must know that the average drift speed is in the order of mm per second. Stick to Current, as all good Engineers do and save yourself from a further level of complication.

    Also, charges do not just take 'the easiest route'. The current is shared according to the resistances of all possible paths. In a simple circuit, this may only involve one significant path but in cases like this, it's anyone's guess, without more information.
     
  13. Sep 29, 2014 #12

    dlgoff

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    Electrons don't move very fast in a wire even though lots of energy is being transferred.

    micohm.gif

    http://hyperphysics.phy-astr.gsu.edu/hbase/electric/ohmmic.html
     
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