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Re: [Phys-l] Chimp unsuccessfully hangs from high voltage line



When I was growing up on a dairy farm some very long time ago, we used
electric fences to separate pasture lots, corn fields etc. I remember
one time we let the new yearling calves out and one of them ran into the
fence and got tangle up, was laying on the ground and jolting with the
pulsating electric shock. My dad went over and grabbed her, trying to
help her get off-not a good thing to do before turning off the voltage
source. Painful but not fatal.

Warren

"Matt Coia" <matt.coia@gmail.com> 8/27/2006 9:36 AM >>>
I seem to recall using long grass blades to "test" to see if a fence
was
on. By using the grass as an insulating buffer between your hand and
the
fence, you can minimize the jolt to a light tingle in a live wire. Of
course, I've had my share of full jolts, too! :)

Matt


On 8/26/06, Brian Whatcott <betwys1@sbcglobal.net> wrote:

At 07:45 AM 8/26/2006, Joe, you wrote:
Some years ago, I had a crazyish uncle who had a small resort in
the
Catskills, and decided it would be fun to have a chimp to entertain
the guests. While as it happened, one day the chimp got away. Now
this "resort" was in the middle of cow pasture country, a very
lovely
setting with pastures separated by electric fences...a single wire
with some high voltage on it. There was enough internal resistance
in the power supply so that animals got shocked by not killed.
///
Joseph J. Bellina, Jr. Ph.D.


I have lately developed a personal interest in electric fences.
During a hot Summer, when grass easily burns out, horses are tempted
to reach through wire to the greener grass on the other side.
If that wire is barbed, they cut ears, shoulders, legs etc., in
reaching
through. Unlike cattle, they are said to be slow to learn from
their
cuts.

Horse owners like to place an offset electric wire, to keep them
back.
The ordinary sort of fence charger resembles an induction coil,
which
pulses the fence wire with a high voltage pulse.
(Some are apparently configured like a transformer, instead)

The source impedance is high enough to avoid permanent injury to
animals. But this leads to a problem. The grass that is no
longer
nibbled, grows to touch the wire, and this can easily emasculate
the pulse.

A recent approach to fence charging takes a different tack: a high
voltage pulse is still generated, but now, its output is lower
impedance.
Instead, its duration is limited in order to avoid injuring the
quadrupeds. These are billed as "Low impedance" in that they are
not disabled by moderate grass/weed loading.
Chargers are also rated by pulse energy:
0.1 J to 1.5 J are to be seen in the feed store.



Brian Whatcott Altus OK Eureka!


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_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l