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| The movies below
are examples of what can go wrong. Don't try this at home! |
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345kv_switch.mpeg
- Air break gang disconnect switches are not normally intended
to actively switch load current. This shows three phase 345 kV arcs
that are likely due to relatively low reactive currents, such as from
line charging or unloaded transformers, and not a full load break. At
the
very end of the video, a brief phase-to-phase power arc causes an
upstream Oil Circuit Breaker (OCB) to blow, finally extinguishing the
arcs! Originally found on More
Arcs
'n Sparks! |
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lugo_swr.mpeg
- This
video clip shows a three-phase air disconnect
switch opening line reactors in a 500 kV transmission system at the
Lugo substation near Los Angeles, California. The utility was having a
difficulty cleanly
disconnecting these reactors and had set up a test to help isolate the
problem. A set of SF6 gas puffer interrupters (to
the right of the air break switch) open first. However, at the start of
the clip one phase flashes over the outer bushing of the interrupter.
This causes one phase of the air break switch to open "hot", and it
begins arcing. The resulting hot arc grows
and rises until it easily exceeds 50 feet. Finally, an upstream Oil
Circuit Breaker (OCB) is commanded to open, abruptly
extinguishing the arc. As impressive as it is, this switch is NOT
breaking a real load. The arc is "only" carrying the relatively
low capacitive charging current associated with energizing an unloaded
transmission line (~20-25 amps). A break under
full load would be MUCH hotter and extremely destructive... imagine a
fatter, blindingly bright 50 foot welding arc. Originally found on More
Arcs 'n Sparks! -- More details |
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xfrm_blast.mpeg - A
power arc to
ground on the low voltage side of this substation behaves like the
welding torch from Hell,
chewing up everything in its path. Protection hardware either fails to
open the HV side or is unable to
detect the presence of the arcing ground fault. Excessive current
eventually causes the substation's power
transformer to overheat, severely cooking its innards, and causing the
mineral inside to begin boiling. The transformer's
pressure release valves then vent a mist of hot oil vapor which
subsequently ignites and explodes in a ball
of flame. The forceful explosion of an expulsion fuse finally cuts
power with a bright blue flash and BANG. However,
by this time, the weakened tank of the transformer fails, spilling
flaming oil onto the already devastated substation. Originally fouond
on More
Arcs 'n Sparks! |
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Coin
shrinking - What a million amps
does to a quarter. The Quarter Shrinker uses a technique called high
velocity electromagnetic metal forming, or "Magneforming". This
technique was originally developed by the aerospace industry in
conjunction with NASA, and has been popularized by Aerovox, Grumman,
and Maxwell. It involves quickly discharging a high energy capacitor
bank through a work coil to generate a very powerful and rapidly
changing magnetic field which then "forms" the metal to be fabricated.
While it works best with metals of relatively high electrical
conductivity such as copper or aluminum alloys, it will work to a more
limited extent with poorer conductors such as sheet steel. |
