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Thread: More fallacious grounding

  1. #31
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    [QUOTE=mbrooke;2000922]
    Quote Originally Posted by Fulthrotl View Post




    For a portable generator? Show me the code section which requires it
    ahem. you brought the pamphlet. you back it up.
    ~New signature under construction.~
    ~~~~Please excuse the mess.~~~~

  2. #32
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    Depends- feeding a building or stand alone?
    Last edited by mbrooke; 06-10-19 at 01:08 AM.

  3. #33
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    Quote Originally Posted by GoldDigger View Post
    Actually, a very firm NO to that.
    In both theory and practice, the movement of current through a near infinite three dimensional solid is such that once you correctly subtract the interface resistance of the ground electrodes at both ends, the additional resistance of the path through the earth itself, regardless of distance, is so close to zero as to be negligible. Cross country telegraph circuits proved this quite well. Higher resistance over long distances was entirely the result of the metal line impedance. Modeled as a transmission line with resistance, capacitance and inductance but with a perfect return conductor (except for electrode interface resistance.)


    Then why are uni grounded system treated as ungrounded systems miles down from the substation?

  4. #34
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    Quote Originally Posted by mbrooke View Post
    Then why are uni grounded system treated as ungrounded systems miles down from the substation?
    1. Can you recommend a reference for that? I would like to understand it better.
    2. The term uni-grounded has different consequences in the context of a single premise system and the context of a transmission line with a lumped load at the end.
    3. My first impression would be that if, as you say, the system with a ground reference ONLY at the substation and not at the load end, is considered ungrounded (from the point of view of induced transients?) it is not because of earth resistance but rather because of the impedance of the line conductors themselves.
    4. A system with a grounding transformer at the load end with only a local ground electrode rather than a metallic neutral would, IMHO, be considered solidly grounded. The resistance of the earth path is not a factor in whether or not the system is considered solidly grounded.

  5. #35
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    Earthing is like a secret society or elite club: it's hard to get in, but once you're in, you're in. I think an MGN is able to keep neutral to ground voltage low because of the extensive number of electrodes throughout the system. You kinda have to be all in or all out. If you're not all in, you probably need to just not treat the neutral as grounded.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  6. #36
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    Quote Originally Posted by GoldDigger View Post
    1. Can you recommend a reference for that? I would like to understand it better.
    2. The term uni-grounded has different consequences in the context of a single premise system and the context of a transmission line with a lumped load at the end.
    3. My first impression would be that if, as you say, the system with a ground reference ONLY at the substation and not at the load end, is considered ungrounded (from the point of view of induced transients?) it is not because of earth resistance but rather because of the impedance of the line conductors themselves.
    4. A system with a grounding transformer at the load end with only a local ground electrode rather than a metallic neutral would, IMHO, be considered solidly grounded. The resistance of the earth path is not a factor in whether or not the system is considered solidly grounded.
    I'm trying to find something good, but nothing on the physics of why that is.


    If you look at lightning arrestor sizing, uni grounded has its own category like ungrounded.


    I'd PM Mivey, he would know what that is.

  7. #37
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    Quote Originally Posted by myspark View Post
    How would people know if the phrase had not been published.

    To paraphrase Tom Lehrer, "Stealing from one source is plagiarism. Stealing from multiple sources is research!"

  8. #38
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    Quote Originally Posted by roger View Post
    So I ask that you watch all threads (I mean all threads) from this point on and make sure a quote is not plagiarized and TIA

    Roger
    LOL
    BB+/BB=?

  9. #39
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    Quote Originally Posted by GoldDigger View Post
    Actually, a very firm NO to that.
    In both theory and practice, the movement of current through a near infinite three dimensional solid is such that once you correctly subtract the interface resistance of the ground electrodes at both ends, the additional resistance of the path through the earth itself, regardless of distance, is so close to zero as to be negligible. Cross country telegraph circuits proved this quite well. Higher resistance over long distances was entirely the result of the metal line impedance. Modeled as a transmission line with resistance, capacitance and inductance but with a perfect return conductor (except for electrode interface resistance.)
    He said unigrounded, and is correct.
    BB+/BB=?

  10. #40
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    Quote Originally Posted by GoldDigger View Post
    1. Can you recommend a reference for that? I would like to understand it better.
    2. The term uni-grounded has different consequences in the context of a single premise system and the context of a transmission line with a lumped load at the end.
    3. My first impression would be that if, as you say, the system with a ground reference ONLY at the substation and not at the load end, is considered ungrounded (from the point of view of induced transients?) it is not because of earth resistance but rather because of the impedance of the line conductors themselves.
    4. A system with a grounding transformer at the load end with only a local ground electrode rather than a metallic neutral would, IMHO, be considered solidly grounded. The resistance of the earth path is not a factor in whether or not the system is considered solidly grounded.
    To keep it simple, picture the neutral and egc at a panel as being at the same potential then diverging as you move down the feeder. An Earth bonded wye point at a substation puts Earth at the neural point of the phases. As we move well away from that location, the neutral point begins to float away and eventually Earth is practically unbonded from the neutral point.
    BB+/BB=?

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