Hi, I was surprised that more people didn't comment on this video,
available on the Internet.

This is a 500 KVolt Power line, opened while energized, but with the load
removed from the circuit. The arc rises to about 100 feet before, according
to the article, another circuit breaker was opened elsewhere, an OCB, (Oil
Filled Circuit Breaker) and the arc extinguishes.

To quote one person from another site "This is the coolest f-----g thing
that I've ever seen".

Go he http://205.243.100.155/frames/longarc.htm

Click on the picture entitled "NEW MPEG of a 500 kV disconnect switch, one
phase opens hot!".

The Direct link is : http://205.243.100.155/frames/mpg/500kV_Switch.mpg

Have fun.


From an engineering site, this explanation:


http://www.engr.usask.ca/classes/EE/442/main.html
"*The video clip shows a three phase air disconnect switch attempting to
open the high voltage supply to a large three phase 33 Million Volt Ampere
Reactive (MVAR) shunt line reactor. The reactor is the huge transformer-
like object behind the truck at the far right at the end of the clip. The
clip was believed to be part of the 500 kV Lugo substation near Los
Angeles, California. Line reactors are large inductors which are used to
compensate for the effects of line capacitance on long extra high voltage
(EHV) transmission lines. The utility was having difficulty cleanly
disconnecting the line reactors and had set up a special test to videotape,
and hopefully isolate, the problem. If you look carefully, you can see
evidence of previous arcing - notice the blackened horizontal bushing
(insulator) just behind the bushing that arcs at the beginning of the MPEG.

Normally, pressurized sulfur hexafluoride (SF6) gas "puffer" interrupters,
just to the right of the air break switches, will first de-energize the
circuit so that the air break switches can the open with no current
flowing. The actual switching elements for the interrupters are hidden
inside the horizontal bushings. However, as the interrupters open, a high
voltage switching surge causes one of the interrupter bushings to flash
over. Since this phase remains energized, the air break switch for this
phase opens "hot", and it continues arcing as the switch swings to the
fully "open" position. The arc continues to grow upward, driven by rising
hot gases and writhing from small air currents, until it easily exceeds 50
feet. Long arcs usually terminate before by connecting to an adjacent phase
or to ground, causing a detectable fault which then trips out the circuit.
This particular arc could have persisted for quite some time, but the
utility manually commanded an upstream Oil Circuit Breaker (OCB) to open,
abruptly extinguishing it.

As impressive as this may be, the air switch was NOT disconnecting a real
load. The arc is "only" carrying the relatively low (perhaps ~20 amp)
magnetizing current associated with the line reactor. The 94 mile
transmission line associated with the above circuit normally carries over
1,000 megawatts (MW) of power between Nevada and California. An actual
break under normal loading conditions would have been MUCH hotter and
extremely destructive. Imagine a fatter, blindingly blue-white, 100 foot
long welding arc that would vaporize the contacts on the air break switch
and then work its way back to the feeders. But, you've gotta' admit that
this "little" 10 million Volt Ampere reactive arc is still pretty awe
inspiring!"

"Dilbert" wrote in message
...
Hi, I was surprised that more people didn't comment on this video,
available on the Internet.
Go he http://205.243.100.155/frames/longarc.htm

Some cool videos and pictures there. Thanks for posting the link.