Hurricane Sandy

[glatt]

Heard a loud BOOM about ten minutes ago. Sounded like a transformer going. Facebook comments indicate they lost power two blocks over. Makes me wonder exactly what in the transformer is making that boom noise when it goes. When a circuit breaker in my house trips, it just makes a loud click.

Wind still isn't very bad at all, but occasional strong gusts. Steady rain for a few hours now.

Meanwhile, Arlington County email alerts seem designed to put the fear of God in people.

[Ibby]

Originally Posted by glatt

Makes me wonder exactly what in the transformer is making that boom noise when it goes. When a circuit breaker in my house trips, it just makes a loud click.

I got curious.

Why Do Transformers Explode?
Transformers explode when an electric power line running to a transformer suddenly transmits far too much electricity for the circuits within the transformer to process. The most common way that this can happen is during a lightning strike. There are automatic shutoffs within the transformer when too much power reaches it. They turn off within 60 milliseconds of having detected an energy spike; unfortunately, this is about 5 times too slow to do any good. The extra electricity heats up and melts the circuit. The circuits are made to be heat resistant and are kept cool by several gallons of refined mineral oil in a closed chamber. Despite this, the circuit becomes red hot and fails in a shower of electrical sparks, superheating and igniting the mineral oil. The mineral oil combusts explosively, causing a loud bang and sending metal shrapnel that was once the transformer scything everywhere.