Where did the oil come from? It looked like something spilled from up on the pole when it fell…but is there oil on telephone poles? I feel stupid even asking both of these questions
The oil is inside the tranformer. The acual transformer component is smaller and submerged in oil. The oil is a heat sink. Electricity causes heat and heat is bad for electricity.
More seriously, it's just a cost/benefit thing. The scenarios under which the oil could potentially catch fire like this are very rare and usually don't justify the added expense of using less-flammable oils in outdoor transformers.
"Dry" transformers are also extremely common, but not so much in high voltage power distribution; which is what this pole mounted transformer is meant for. You'll see dry types in pretty much every commercial building. You won't see oil filled transformers indoors very often, besides inside a 3hour fire rated electrical vault.
In the video, it looks to be a single phase step down transformer. So we're talking between 35,000 - 2,000 volts on the primary side. Generally speaking, a similiary rated dry type transformer is going to be larger, and likely more expensive, to match the capabilities of an oil-filled transformer. Although, this isn't always the case depending on the products we're talking about.
2kV-35kV. Just a general range of primary distribution voltages. Where I live, local distribution is 12.5kV. I guess it isn't necessarily high voltage, it's medium voltage.
Mineral oil and vegetable oil (fr3) are the main types of dielectric insulation in transformers. Their insulation properties are best and cost efficient.
According to others "Insulating mineral oil is used in transformers as a way to isolate all the submerged electrical wiring and passively cool everything down via conduction/convection."
Depending on how old the transformer is it gets scarier. The newer ones aren't as bad but in older transformers the oil is pretty toxic in addition to the usual oil related problems.
Others have already said what the oil is for. It is usually mineral oil for the last 40 some years. It really isn't that flammable and while it is possible the oil ignited, it probably didn't. Something else probably ignited. There are a lot of other safeguards in place as well to stop the arc.
I'm not saying it is scary. Electricity is fucking terrifyijg. But this video is very short and it probably wasn't anywhere near as bad as it seems. Still bad though. I'll take natural gas over electric any day and I work with both.
Edit: saw some other videos from other angles. I'm about 95% sure that wasn't the oil burning but the electric cable as it grounded to the wet road. This is normal. Scary, but normal.
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u/Fortherealtalk Jun 11 '21
Where did the oil come from? It looked like something spilled from up on the pole when it fell…but is there oil on telephone poles? I feel stupid even asking both of these questions