## User Tag List

1. Originally Posted by SG-1
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

2. 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. Senior Member
Join Date
Oct 2007
Location
New Jersey
Posts
6,335
Mentioned
0 Post(s)
Tagged
Originally Posted by FionaZuppa
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. Originally Posted by FionaZuppa
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.

5. Senior Member
Join Date
Oct 2007
Location
New Jersey
Posts
6,335
Mentioned
0 Post(s)
Tagged
Originally Posted by LarryFine
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. Originally Posted by LarryFine
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.

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. Senior Member
Join Date
Oct 2009
Location
Austin, TX, USA
Posts
10,459
Mentioned
0 Post(s)
Tagged
Originally Posted by LarryFine
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. 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.

9. gar
Senior Member
Join Date
Apr 2008
Location
Ann Arbor, Michigan
Posts
7,497
Mentioned
1 Post(s)
Tagged
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. Originally Posted by LarryFine
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.

#### Posting Permissions

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