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Transformer fires..

We had a visit from Mother Nature two days ago; the 3rd this week. She practiced her "microburst" technique on trees in the area.

This resulted in a number of primary feeders [13.2KV] being on the ground rather than between poles.

The next morning; a cop told me there were some transformer fires. In one place, there are 3 small [oh, maybe 25KW] pole pigs on a pole

-- they feed 3PH to the dentist office in addition to the separate single phase. Sure enough, 2 of the three pig cases are now badly charred, but intact.

And farther down the road; a single-phase pig was also scorched.

Now the interesting thing was in both cases the secondaries were quite intact. And the inline fuses looked intact as well. (I've been told the 10-15A 7600v fuses eject to 30 degree position when they blow, so the line crew can see such from the ground.

[There was NO way such had been fixed by then, primaries were still all over the place then.]

The only time I've seen a pig catch fire; it was from overheating on a long-term overload; such as a heat wave when I was in FL. Shorted secondaries just cleared the fuses.

So what could have caused these?

(BTW; more physically impressive was the restaurant down the road a ways. There, the 3PH pigs are far bigger than the dentist or the one 75KW I have out front. A large tree came down, wiped out 2 cars [one was the chef's...] and on the way, pulled down the 3PH+Neutral

4/0 cable.

THAT pulled all three cans off their mounts and left them swinging from the primary fuses and returns. It took until 5pm before a contractor for PEPCO got them back in place.)

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Reply to
David Lesher
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The most impressive "show" I remember was the ice storm of... February

1999, was it? An inch or more of ice formed on all the trees and wires in the area, beginning early in the evening. We lost electricity quite early, and in the dark of our house we could look out the windows and see a bright blue flash in the sky every few seconds, followed by a "pop" for the nearby ones. These were trees falling on lines, shorting out lines. The noise was so consistent that it was like popcorn popping, a pop every couple seconds. We were without electricity for a whole week before Pepco got our neighborhood hooked back up. All the fridge stuff went to the garage to keep frozen, and we did a lot of eating out...

Oh yeah, the driveway iced over too that day, it's a rather steep downhill slope back to the main road and by the end of the night we had a USPS, a Fedex, and a UPS truck all in our driveway. They slid packages down the driveway to other trucks the next day, and a couple days later they actually retrieved the trucks.

Reply to
Tim Shoppa

Interesting.

We had a impressive show when hurricane Juan ripped through Nova Scotia, Canada. When they were restoring the high tension lines, we would hear a great big hhhuuuummmmmmmmm, when the pitch black sky would turn pinkish blue, and the light was almost as bright as daylight! This happened for several days as the high tension lines were slowly restored. Sometimes, after we got our power back, we would hear the sound and the power would go back out as a substation would blow it's breaker. The power company had to shut down some of the power plants. Repair crews were brought in from all over the place. I had no problem, since we shared a 5kw generator with a neighbor, and UPS's for a few hours late at night.

Reply to
Jeff

We get, ah....."interesting" weather here in Central Okla. Just about every spring and fall we have outbreaks of severe weather. Sometimes I go to the OU campus, to one of the tallest buildings in the area and watch the storms blow in. You can frequently tell where gust fronts are by the progression of blown transformers and power line flashes.

On a side note, I was at a friend's farm just outside Oplin, TX when a big lightning storm came through. Being way outside "civilization", the power came down 3 17KV(?) lines. Every time there was a nearby lightning strike, the lines would glow pink for a few seconds and hum loudly. What was especially strange was you could see the pink glow progress down the power lines up to the locan transformer.

Reply to
Dan Major

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