waveforms of signal between neutral and earth

Discussion in 'General Electronics Chat' started by jindaljatinjj, Aug 16, 2010.

  1. jindaljatinjj

    Thread Starter New Member

    Aug 16, 2010
    3
    0
    AC(alternating current) means that for half cycle current goes out from one wire and is received when it comes out of load and reverse happens for the other half the cycle. (i am talking only of 1 phase here)

    so,i wanted to know what is the waveform of signal between neutral and earth (assuming neutral is grounded at the distribution panel) when the phase being talked about is going in its negative half cycle.

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  2. timrobbins

    Active Member

    Aug 29, 2009
    318
    16
    Assuming a perfect setup with no parasitics, then there is no signal. But if you have impedance between your sense point on neutral wire and the coupling bond from neutral to earth, then you will see a waveform that is your neutral current signal mulitplied by the impedance.
     
  3. jindaljatinjj

    Thread Starter New Member

    Aug 16, 2010
    3
    0
    hey timrobbins thanks for reply.
    i am sorry but i could not understand clearly the meaning.
    can u plz give me some name of book/reference from where i can learn more about this.

    also i wanted to know that will the signal present in hot wire (wrt to earth) be of the form half rectified ac (in case of grounded neutral,1phase circuit)?
     
  4. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    In a perfect world Neutral and Ground are dead, absolutely zero ohm shorts to each other.

    In the real world the #12 or #14 neutral wire floats a bit above the Ground wire or raceway (conduit) that forms it. This is because the Neutral wire carries actual circuit power whereas the Ground carries nothing except in a fault condition.

    In the real world it pays to verify that your Neutral is near zero ohms in relation to ground at all your outlets. Too many instances of outlets being replaced and the Ground not properly hooked up. There also exist cases where there was no actual ground wire to begin with (usually in in older circuits) so many just hook the Ground and Neutral together at the duplex outlet. Better than nothing but not actually proper. By code if you run into one of these situations you're supposed to use a replacement duplex outlet that has no ground terminal provision or, if feasable, run a separate ground.

    In commercial circuits or any other place conduit or MC cable is used it also pays to verify that Ground is near zero ohms in relation to Neutral. Conduit conectors &/or running splices often get loose (especially the single screw type) and the nut that holds the connector to the metal box isn't always fully tightened. I always use compression type connectors on conduit, far more reliable both electrically and mechanically.
     
  5. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    It's AC voltage, there's no DC or anything like it present. You have a hot conductor which is varying between positive and negative by 120 V RMS in relation to the neutral which is considered to be your zero reference point.

    See http://en.wikipedia.org/wiki/Mains_electricity
     
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