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Thread: Question about Step-Up Step-Down Transformer Neutral Wiring

  1. #21
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    This is the feed side. I traced that through bunch of manholes and pull boxes. There were three conductors - Two Blacks and a Green .
    I remember sticking my hands in the dirt at the #4 pull box and getting nasty buzz. I was so happy enough to find the Route so I never opened up the Step Up Transformer
    but downstream of the Step-Up Transformer, there is this Switch (2nd picture) that I did open where the Two Blacks became Red. There was No Ground or Neutral at the Switch.
    When I get back to the Site,I'll trace and meter everything carefully, but I have a lot of pictures showing Grounding done locally to a Block in the Square Duct on the Frame both at the Step Up Side and the Step Down Side.

    So that's what started my Original Post -I had questions about how to derive or identify the Ground or Neutral for a Step Up and Step Down transformer. I need to get a Meter on each of the two Blacks going across the Manholes and Pull Boxes

    Thank you everyone for your Help..
    Click image for larger version. 

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    Last edited by Installer; 04-18-19 at 11:43 AM.

  2. #22
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  3. #23
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    190418-1109 EDT

    Installer:

    You need to get some books on electrical theory, and along with these some components, power supplies, and instruments. Then study and play.

    Alone all by yourself you will not be able to figure things out. In the evolution of the study of electricity is was probably well over 100 years that study of electricity was needed, for persons on their own, to get to the state of knowledge we have now. I am using roughly the time frame from 1800 to 1900. That accumulated knowledge is now contained in books, etc., for you to study.

    Some points ---

    1. "Voltage" is measured between two points. Those points need to be defined.

    2. A "voltage gradient" is measured at a point. This is how rapidly voltage changes from one point to another, but at an infinitely small incremental change of distance. Usually associated with electric fields.

    3. "Current" is measured at a point.

    4. To know how transformers work you need to study electromagnetic fields and their interactions with each other. Same for motors.

    .

  4. #24
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    Quote Originally Posted by Installer View Post
    Yes that's what's confusing me. Also I should have traced where the Ground and Neutral were coming from , that was my fault and its important. I also didn't check the Step Up side.

    BTW I appreciate everyone's feedback and replies . Thank you very much, I've learned a lot from this post

    BTW But its a bit confusing and humbling with everyone shouting at me so when I get to the Site I'll trace everything very very carefully on both sides

    I'll take the New transformers for the Second Feed out of the box and see the leads,and set them up on a bench and test them and meter everything and try figure it out

    I may be inexperienced but my parents were immigrants and I learned from them --If you hustle and are conscientious and work hard you will get there ,
    Do you realize you can ground any point in the system? If you are grounding a system and it has a neutral conductor, NEC generally requires the neutral to be the conductor that is grounded, but you could ground any conductor of the system, you just can't ground more than one or you end up with undesired current through the grounding means.

    A neutral is a conductor with equal potential to other points of the system, most common examples are the center tap of a single winding source or the mid point of a three phase wye system.

    With a two wire secondary, you have no neutral. You can ground either lead to create a grounded conductor though. That grounded conductor is still white or gray if you are to comply with NEC requirements.
    I live for today, I'm just a day behind.

  5. #25
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    Thank you everyone and thank you for putting up with me.

    Thank you everyone and thank you for putting up with me.
    I'm going to do exactly as everyone says.
    I was wrong .
    When I get back there in several weeks, I will carefully document and trace and put a voltmeter on everything .
    Thanks for having me on this Site and not booting me off of it for being so stubborn.

  6. #26
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    If this site booted people for being stubborn, most of us would not be here anymore!

    We are here to help, even if crotchity replies.

  7. #27
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    Quote Originally Posted by kwired View Post
    ...you just can't ground more than one or you end up with undesired current through the grounding means.
    Very diplomatically put.

  8. #28
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    190420-0937 EDT

    Installer:

    Going back to your first post drawing and the left transformer. I would put a round dot near the top end of the X1 winding to indicate phasing. Then a round dot at the top end of the X3 winding. Now you see the two coils are in series opposition. Thus, magnetically you have close to a short circuit between A and B.

    A transformer does not define a neutral. Neutral is a term relating to a circuit and relating to currents and voltages. The concept of neutral was created by Edison as a means to reduce copper usage in the distribution network.

    In the first post your left transformer drawing should be changed so wire B is connected to X2X4 and X1 should have a wire to X3. Neither A or B is a neutral.

    If winding X1X2 is rated 120 V, then winding X3X4 must also be 120 V.

    On the output end, if the wiring is as shown, then there is no problem other than the voltage between E and F will be zero. If wiring on the output side is corrected so there are only two terminals E and F, and the output is 120 V, then there is no neutral, but there should be a grounded terminal. Either E or F could be the grounded terminal.

    If the output were changed so X2 and X3 were connected together, and this went to a terminal F, and the wire between X2 and X4 was removed, and X4 went to a terminal G, then F could be called neutral, if the load was balanced and current to F was minimal.

    Even, if there were no load on G, then most people would still call F neutral.

    The original purpose of neutral was to eliminate one wire. Four wires down to three.

    .

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