User Tag List

Page 13 of 15 FirstFirst ... 3 11 12 13 14 15 LastLast
Results 121 to 130 of 146

Thread: Experiments

  1. #121
    Join Date
    May 2005
    Location
    Richmond, Virginia
    Posts
    24,282
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by SG-1 View Post
    If you have any of Ben Franklins DNA you might want to stroll around during a thunderstorm with your new Fluorescent tube handled umbrella & see how that lights up your path.
    "I don't think so, Tim!" ~ Al Boreland
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  2. #122
    Join Date
    May 2014
    Location
    AZ
    Posts
    2,463
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Here's an interesting idea. A whole bunch of people (a lot of them) standing under HV lines will in fact change the impedance of the lines. Why? Because the human body has less electrical resistance than air does, thus the leakage current now has less ohms between lines and ground

    You can also take a whole bunch of rebar, glue a part of their end into pvc, jam the pvc into the ground, place a whole bunch of them between two towers (which can be 100yds or more), rebar stands 5-6ft in the air. Now connect all the bottoms of rebar together with wire (bond them just above the pvc, above the gnd, etc) and then take a wire from the last rebar and connect a load between it and the earth (or metal of a tower). Power away folks, power away.

    Ever wonder what happens to the line impedance when it rains? HV perhaps saves more from low amps but also has some challenges dealing with leakage and impedance fluctuations.

    Wrapping the lines in say a pvc sheath would help the poco, but that's extra cost and weight.

  3. #123
    Join Date
    Oct 2007
    Location
    New Jersey
    Posts
    6,335
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by FionaZuppa View Post
    Here's an interesting idea. A whole bunch of people (a lot of them) standing under HV lines will in fact change the impedance of the lines. Why? Because the human body has less electrical resistance than air does, thus the leakage current now has less ohms between lines and ground

    You can also take a whole bunch of rebar, glue a part of their end into pvc, jam the pvc into the ground, place a whole bunch of them between two towers (which can be 100yds or more), rebar stands 5-6ft in the air. Now connect all the bottoms of rebar together with wire (bond them just above the pvc, above the gnd, etc) and then take a wire from the last rebar and connect a load between it and the earth (or metal of a tower). Power away folks, power away.

    Ever wonder what happens to the line impedance when it rains? HV perhaps saves more from low amps but also has some challenges dealing with leakage and impedance fluctuations.

    Wrapping the lines in say a pvc sheath would help the poco, but that's extra cost and weight.
    I don't think that's correct. As gar has pointed out, there is no leakage current with pure capacitive coupling. You need something that is actually putting a load on the system to get current flow.

  4. #124
    Join Date
    May 2005
    Location
    Richmond, Virginia
    Posts
    24,282
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by FionaZuppa View Post
    Ever wonder what happens to the line impedance when it rains?
    According to my EE friend, damp air has greater impedance (higher dielectric strength) than dry air, not less.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  5. #125
    Join Date
    Oct 2007
    Location
    New Jersey
    Posts
    6,335
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by LarryFine View Post
    According to my EE friend, damp air has greater impedance (higher dielectric strength) than dry air, not less.
    In my last house I had a plug-in fluorescent fixture over a very small workbench. As there was apparently no vapor barrier under the sort-of concrete floor, it was perpetually damp in the warmer months. During such times, I would have to touch the lamps in order to get them to fire up.

  6. #126
    Join Date
    May 2014
    Location
    AZ
    Posts
    2,463
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by LarryFine View Post
    According to my EE friend, damp air has greater impedance (higher dielectric strength) than dry air, not less.
    I suspect not. Here's a real world example to explain it.

    Data centers do not allow humidity to drop too low,,, why? Because when the air is dry it allows static charge to build up on objects. Having moisture in the air provides more "conductor" and less "insulator", thus no static charge buildup. In other words, there's more free electrons available with water in the air. Remember, when water (not steam) is in the air its usually not 100% pure water, etc.

    Quote Originally Posted by gadfly56 View Post
    I don't think that's correct. As gar has pointed out, there is no leakage current with pure capacitive coupling. You need something that is actually putting a load on the system to get current flow.
    Things sticking up under HV lines are not ideal caps. And, its alternating field at 60Hz, and we know caps "pass" current in alternating e field. A cap is physically an open circuit, but will appear to pass current when its subject to e field that has Hz, etc. All caps have leakage even when placed in a vacuum.
    Last edited by FionaZuppa; 01-11-19 at 07:28 PM.

  7. #127
    Join Date
    Oct 2009
    Location
    Austin, TX, USA
    Posts
    10,459
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by LarryFine View Post
    According to my EE friend, damp air has greater impedance (higher dielectric strength) than dry air, not less.
    I suspect that either he was mistaken or you misunderstood him. A vacuum has the highest dielectric strength.

  8. #128
    Join Date
    Jul 2009
    Location
    Ware Shoals, South Carolina
    Posts
    1,258
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I think GAR was speaking of conduction current, no electron flow.

    If you wire a light bulb in series with a capacitor it burns just fine. Yet no electrons pass through the capacitor. The electric current through the capacitor is displacement current, no charge flow.
    Advise is a dangerous gift, even from the wise to the wise.

  9. #129
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    7,497
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    190111-2127 EST

    An ideal capacitor dissipates no energy as heat when an AC current flows thru the capacitor.

    Generally when leakage is used with the discussion of a capacitor it refers to resistive components of the capacitor that dissipates heat as current flows thru the capacitor.

    With respect to power lines there is power lost via objects in the electric and magnetic fields of the power lines. There is also radio frequency radiation at 60 Hz from the power lines, but not much.

    When a new object is placed in the fields of the power lines it places an additional loss load on the power system. The object might reduce some other losses, but it does not totally replace other losses, and therefore it is a new net load on the power system.

    .

  10. #130
    Join Date
    Jul 2009
    Location
    Ware Shoals, South Carolina
    Posts
    1,258
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by LarryFine View Post
    According to my EE friend, damp air has greater impedance (higher dielectric strength) than dry air, not less.
    My research into this indicates that water vapor has a higher Voltage Break Down than dry air. Ions are recombined into the water droplets before they can form into an electric circuit.

    The presence of water on the contaminated surface of insulators & other materials does make a flashover more likely in the presence of corona discharge.
    Advise is a dangerous gift, even from the wise to the wise.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •