> Most Sub station transformers like the one in the video
> which form the looks of the bushing size is at least 69kv
> or possible 138kv normally have fuseing on the High voltage
> size and then go to buss work and feed distribution breakers
> for the journy out to the line system so for my 2 cents
> worth i would have to say there was an equiment failure on
> the lower voltage side of the transformer and that could be
> anywhere from 4kv which in getting scarce up to 13.8kv which
> caust a failure on the transformer tank that lead to the
> massive fire ball that followed what looked to be some kinda
> liquid spraying toward the arc and from what was stated
> earlier in the posting it can take several days to put that
> kind of fire out once it gets going good 1st because you
> cant get at it because the heat
> 2nd from working with fire instructors and hearing the
> stories they had to tell about fires when there were old
> trandfomers being scrapped out and got lit off from a cutting
> torch 1 they worked several days to control
I'd say your guess as to what happens was pretty close. Here's the text
that accompanied the video:
A power arc to ground on the Low Voltage side of this substation creates
an arcing fault that behaves like an uncontrollable welding torch from
Hell, chewing up everything in its path. Protection hardware either
fails to open the High Voltage side or is unable to sense the presence
of the fault. Excessive current eventually causes the windings on the
substation's power transformer to overheat, severely cooking its innards
and causing the mineral oil inside to begin violently boiling. In a vain
attempt to prevent the transformer's tank from exploding, pressure
release valves vent clouds of superheated oil vapor which subsequently
ignites and explodes in a ball of flame. A phase to phase short circuit
occurs, perhaps caused by a flashover within the flames or a heat
induced fault within the transformer. This causes an expulsion fuse to
blow with a flash and a resounding BANG, finally killing power to the
substation.
However, by this time, the weakened transformer's tank fails, and it
spills hundreds of gallons of flaming mineral oil onto the already
devastated substation. Local firefighters can only watch from a distance
since there's no way to safely fight this fire, and the substation is a
total loss. As one fireman quipped, "Firemen don't mess with their
wires, and linemen don't mess with their fires". A very sobering look
at the explosive power silently lurking within the quietly humming
substation in your neighborhood...
What I'd like to know is how/why there was someone videotaping a
substation? Seems kinda fishy...
--- Jeff
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