# Power line videos. Neat stuff

Discussion in 'Electrical Engineering' started by JohnR66, May 15, 2007.

1. ### JohnR66Guest

Confetti causes a flash over between power line conductors. I wonder why it
travels horizontally like that?

I thought this one was pretty neat. A linesman servicing HV lines from a
chopper.

2. ### Andrew GabrielGuest

Do a search on Jacobs Ladder Arcs.

3. ### Guest

| Confetti causes a flash over between power line conductors. I wonder why it
| travels horizontally like that?
|
|
| I thought this one was pretty neat. A linesman servicing HV lines from a
| chopper.
|

Do you have normal videos for these? YouTube still can't figure out what
version of Flash player my browser has (likely because their code does not
understand Linux).

4. ### JohnR66Guest

Heat seems to pull the arc up, but this is horizontal and judging by the
sparks there is little or no wind.
John

5. ### John RyeGuest

Hello All

I have not seen the video, but if you have a pair of parallel wires, and
establish an arc between them it will travel along the wires away from the
power source. Remembering that the arc could be replaced by a piece of wire,
if you work out the force on the piece of wire, by doing the appropriate
integrations on the fundamental equation Force = Flux Density x Current x
Length you will find that with a few thousand amperes of current there is a
significant force in this direction.

There is a message in this for those investigating equipment failures. That
is that the major damage will be where the arc ends up. The place where the
failure started is usually somewhere back towards the supply from this point.
You can usually find a series of bright spots on the conductor where the arc
was stationary for a few milliseconds.

If you consider single phase ac supplies the arc will often go out for a
short time at current zero and then restrike.

John

6. ### The Great AttractorGuest

Some local lines have coatings on them, and the burn travels along as
the coating is breeched.

7. ### The Great AttractorGuest

Totally incorrect. Such arcs operate on the rise of heat in air. This
was HORIZONTAL.

Think before you speak, boy.

8. ### The Great AttractorGuest

What I hate is all these damned sites that allow one to view, but not
save a clip.

They act like they are going to lose money or some such SPAM related
CRAP.

9. ### The Great AttractorGuest

Pretty silly. Arcs find least resistance paths, period. Air ionizes
around them, and some lines are coated, so an arc could move in either
direction.

These were parallel lines, so it likely moved along them as it breeched
the coating on them, blazing a trail as it were.
Any arc that remains stationary is going to heat up the start and
finish points (which each is both for AC) heavily at the location where
it stands in one place.
Since all three phases are not carried on ONE pair of lines, the same
occurs one a three phase system where the arc is typically only on one of
the phases.

10. ### Guest

| On 15 May 2007 12:31:24 GMT, wrote:
|
|>
|>| Confetti causes a flash over between power line conductors. I wonder why it
|>| travels horizontally like that?
|>|
|>|
|>| I thought this one was pretty neat. A linesman servicing HV lines from a
|>| chopper.
|>|
|>
|>Do you have normal videos for these? YouTube still can't figure out what
|>version of Flash player my browser has (likely because their code does not
|>understand Linux).
|
|
| What I hate is all these damned sites that allow one to view, but not
| save a clip.
|
| They act like they are going to lose money or some such SPAM related
| CRAP.

If you can view it, you can save it. You just have to be using software
that obeys the user, or something sniffing the video card buffers. BTW,
features in the new Vista from Microsoft intentonally try to prevent that.

I would not mind watching the video directly from YouTube, if they would
make it work universally. But that probably means they would ose certain
abilities to control other people.

11. ### John RyeGuest

Hello

Agreed that arcs normally find the least resistance path.

Agreed that if the conductors are insulated it will slow the movemant down.

But you are forgeting the magnetic forces. The arc will move away from the
power source, and I have plenty of videos from experiments demonstrating
this. Unfortunately they are on film, and can not therefore easily be put on
the web.
Sorry but no. The arc will run on all 3 phases. If you look at a high speed
film you can see the current zeros occuring on each phase, but except for
these very short breaks, on a three conductor arrangement with bare
conductors there will be arcs on all three conductors.

John

12. ### Don KellyGuest

----------------------------
"The Great Attractor"
--------------

There is a short between lines - current flows- magnetic force is present
and tends to expand the loop and this alone can cause movement of the arc
(and is also a major factor in Jacob's Ladders-more so than thermal
effects).
This arc had little upward expansion so heating wasn't the source. A
Fats, you should be able to try this.

13. ### Don KellyGuest

----------------------------
---------------
Actually the most common arcing fault on a 3 phase system is line to ground
on one phase. However, it can, if not cleared become 2 line to ground and
then involve all 3 phases.
In many cases single pole clearing and reclosure works well.
--

Don Kelly

---

14. ### The Great AttractorGuest

Try "Devil Ducky" and hunt up the same clip.

http://www.devilducky.com/all/

15. ### The Great AttractorGuest

Look again. THAT WAS a three phase line, but only two lines were
arcing.

Nice guess though.

16. ### The Great AttractorGuest

I have had jacob's ladders where the arc sits at the bottom without
moving up the conductor pair at all.

The thing needed adjustment, and the ACTION was effected by THERMAL
energy carrying the arc up the non parallel conductor pair. Since the
top is wide, when the arc finally quenched, a new arc forms at the bottom
(least resistance path), and the process starts again.

It is 100% thermal in air, with the ONLY exception being in a vacuum
vessel. Then, I would suspect that there is STILL some air in there.

17. ### Don KellyGuest

"The Great Attractor"
Of course, in a Jacob's ladder, the current is small-typically the supply
is a Neon transformer. In a power line arc, the current will be much higher
and magnetic forces will be appreciable (it doesn't actually take much force
to move the arc). Have you heard of magnetic blowout on LV breakers? Sure a
Jacob's ladder is vertical a) get a little boost from thermal forces. b)
takes up less floor space leaving more room for spectators. c) Thermal
effects help clear the arc at the end (the arc collapses at current 0 so air
movement can break up the arc path).

Yes, I've seen Jacobs ladders for which the arc didn't move. So?

As for a DC Jacob's Ladder- definitely and with a more spectacular effect
such as the arc reaching the end and stretching much further than an AC arc
(at the same current) before going out. Not sure that I would want one.--

Don Kelly
----------------------------

18. ### Tomi Holger EngdahlGuest

That's true. There are some nice extensions for Firefox web broser that