Why Did Our Transformer Blow On A Cool Oklahoma Morning?

I was sitting in the house yesterday morning, trying to get the day started, when a huge pop rang out in the neighborhood.

It sounded like a gunshot, which isn't the weirdest thing to hear in Lawton. It was so loud, it took a few seconds for me to realize the whole house had gone dark.

Texted the neighbors. Same/same.

For the second time this summer, our transformer blew.

It's odd, isn't it? First cooler day in a month, and the electric grid opts to fail with cloudy skies on a cool morning.

I know PSO isn't having the best public relations at the moment, but credit where it's due. Our local linemen were in the alley within twenty minutes, working on the problem. It wasn't out long enough for the house to heat up, which is a pretty impressive turnaround on a big job like that.

Naturally, this became the talk of the nerds at work, and that's where it got interesting.

After a little deep dive, I found out that while it's not exactly normal for transformers and other electrical components to fail after a serious heat wave, there's enough empirical evidence to suggest it's not unusual.

It seems backwards. You'd think the hottest part of the summer would be when everything is most likely to give up. I mean, that's when the grid is being pushed hardest, right?

All that heat creates a tremendous amount of stress on electrical equipment. Transformers spend weeks absorbing that heat, cycling through extreme temperatures and dealing with the additional load being demanded from the grid.

The strange part is that some of the damage doesn't immediately announce itself with a dramatic explosion.

Inside a transformer, you've got insulation, cooling oil, and a whole bunch of components doing their jobs while temperatures rise and fall. That constant thermal cycling creates wear, and some of the little problems can sit there waiting for the right conditions to turn into a very large problem.

While it's not common for these things to fail when the weather changes, it's not unusual either. The load drops. Temperatures fall. Everything starts cooling down and contracting. Those accumulated little weaknesses can finally become an electrical failure.

In other words, sometimes the transformer doesn't blow because it's still 114 degrees outside. Instead, it blows because it finally isn't.

At least that's the best way I can try to describe the incredibly technical peer-reviewed paper I just read about this phenomenon.

Huge shoutout to the AEP power crew that got the neighborhood back up and running in record time yesterday. Even though we barely cracked 100 degrees, it could have made for a noticeable blip on next month's electric bill.