After writing about this (and a couple other) insane high-voltage videos last week I’ve been wondering how this particular flaming arc of electricity came to be. Alan said it looked like a Jacob’s Ladder and, according to what I found today, he’s right! After some creative googleing I found this description on the Stoneridge Engineering website:
This video clip was captured by the maintenance foreman at the 500 kV Eldorado Substation near Boulder City, Nevada. It shows a three-phase motorized air disconnect switcher attempting to open high voltage being supplied to a large three phase shunt line reactor.
The arc stretches upward, driven by rising hot gases and writhing from small air currents, until it easily exceeds 100 feet in length. Switching arcs usually terminate long before reaching this size since they normally flash over to an adjacent phase or to ground.
As impressive as this huge arc may be, the air break switch was really NOT disconnecting a real load. This arc was “only” carrying the relatively low (about 100 amps) magnetizing current associated with the line reactor. The 94 mile long transmission line associated with the above circuit normally carries over 1,000 megawatts (MW) of power between Boulder City, Nevada (from the generators at Hoover Dam) to the Lugo substation near Los Angeles, California. A break under load conditions (~2,000 amps) would have created a MUCH hotter and extremely destructive arc.
Yikes! That’s all I can say.
Check out the High Voltage Sparks and Arcs page for more info on this and some other amazing high voltage fun, including this video of a substation going poof! Despite its vintage design, this page has some cool footage.