Shorting 18 Car Batteries at Once

[wwswimming]

at work the other day, working on a UPS for an
aircraft carrier, i got a hint that something was
"up" by the smell of smoke in the air.

i went back to engineering, and heard the
news. one of our UPS somehow shorted all
the batteries at once.

a typical equipment rack will have a 48 volt
buss. so the circuit converts the battery voltage/
energy to a steady 48 volts. as an example.

i got in to see the equipment later in the day.
we were lucky, no one got hurt.

the inside of the inverter looked like that scene
out of Terminator 2, when they are teleporting
from the future. Arnold and the guy chasing
him time-teleport in sphere's, which vaporize
everything in their path. a chain link fence in
the case of the movie.

that's right before the scene before Ahnold
walks into the bar naked.

anyway, aluminum, epoxy-glass, phenolic,
wire, everything in the path of the thing went
"poof". like a miniature sun. a spherical volume
the size of a soccer ball, Total Hasta La Vista.

perhaps a lot of engineers have a little bit of
inner pyromaniac. everyone in the plant wanted
to see the DUT, device under test, after it blew.

i tried to make a picture. the yellow thing is the
miniature sun part.
http://www.geocities.com/wwswimming/poof.jpg

 

[Modelworks]

Arc welding at its finest !

 

[Peter]

Just one more battery, and that artificial black hole would have been able to sustain itself ...

What ship were you on anyhow, the Nimitz?

 

[CycloWizard]

I was hoping for a video...

 

[BrownTown]

Heh, when I was working for TVA they had some cool explosions of equipment. One time a 500kV 400MVA transformer exploded (they are insulated with oil and FWIW 400MVA = a small cities power) sending flames shooting 100ft into the air. Another time a 161kV capacitor bank shorted out and exploded which is more like what happened in your instance where the metal frame was literally welded together from the discharge. Fortunately nobody was in either substation at the time the capacitor bank blew up, the transformer blew up at a coal plant and shut the plant down for awhile until they could bypass it.

 

[dkozloski]

Years ago the local rural utility company built an electric car based on an old Corvair and using Ni-Cad batteries. Somebody droped a wrench on the battery and it became immediately obvious that Ni-Cads have an exremely low internal resistance and can supply thousands of amps of current to a dead short. The car was completely destroyed and the fire was spectacular.

 

[wwswimming]

well, you know that rule about disconnecting a car battery when you're
doing serious work, like swapping a transmission ?

about 20 years ago i was helping a friend with his BMW 2002 parts,
part of his larger dream of having an antique parts warehouse, also
connected to his subsequent recent divorce.

anyway, i was tightening the new transmission back into place and
snagged a 12 volt wire between the transmission casing and the
engine block. the air in the warehouse was very still. the entire
wiring harness of what was my BMW 2002 floated up into the
air, a perfect ghost of the wiring harness it used to be. wish
i had video of that. almost feel like repeating the experiment
just to get a shot of it.

anyway, the car still ran. i disconnected the transmission as
fast as possible, besides marvelling at the coolness of the smoke
cloud. it ran another 100 miles with charred plastic for insulation
on the wiring harness.

i didn't know that about NiCad's.

 

[jagec]

Originally posted by: wwswimming
well, you know that rule about disconnecting a car battery when you're
doing serious work, like swapping a transmission ?

about 20 years ago i was helping a friend with his BMW 2002 parts,
part of his larger dream of having an antique parts warehouse, also
connected to his subsequent recent divorce.

anyway, i was tightening the new transmission back into place and
snagged a 12 volt wire between the transmission casing and the
engine block. the air in the warehouse was very still. the entire
wiring harness of what was my BMW 2002 floated up into the
air, a perfect ghost of the wiring harness it used to be. wish
i had video of that. almost feel like repeating the experiment
just to get a shot of it.

anyway, the car still ran. i disconnected the transmission as
fast as possible, besides marvelling at the coolness of the smoke
cloud. it ran another 100 miles with charred plastic for insulation
on the wiring harness.

i didn't know that about NiCad's.

You sure you didn't have Kapton wiring?

 

[wwswimming]

it was about a 74 2002. most of the insulation was black in color
before it got fried. didn't look like any Kapton insulated circuit
boards, in color. pretty sure it was old fashioned BMW engine
wire insulation, pre-Kapton.

 

[NeoPTLD]

No fuse?????

 

[jhu]

pics

 

[wwswimming]

no pics. the place was crawling with managers and HR people
and rubber-neckers. it was a situation where sneaking in to
get a pic would have been a "firing offense".

the place was also kind of tense generally. they were under
a huge amount of pressure because the 5 managers who
bought the company had just re-sold it to a British company,
and made all sorts of out-sized promises. including booking
orders just to have a big backlog to show the buyer.

i started there right after the company was sold. as soon
as the company was sold, they tried to cancel orders. they
had booked some projects way below cost, just to have a
big backlog to show the buyer. upper management tried
to back out of those projects; the customer - the Israeli
Defense Forces - threatened to sue. it would have been
a very embarassing lawsuit.

so upper management turned around and said to middle
management, "we bid this 9-month job at 3 months. you
have 3 months to do it." that was the b*llsh*t situation
i walked into as one of the middle managers. after 4
months, i basically told upper management that they were
mis-project-scheduling (the diplomatic version), and pointed
out that they were 1/5 on keeping the promises in the job
offer letter they made to me. i left on fairly neutral terms.

one of the nicer tech's., someone who was quite helpful
when i needed cables and stuff for an EMI test set-up
(cables, antenna, HP spectrum or scalar network analyzer),
subsequently got laid off.

he came back in and killed one of the upper level managers
and another employee.

there were probably some pics of that !