Would attribute to terrorism, myself.
Too small a foot print plus:
- the winter power debacle
- ramping into a warm spring and hot summer
- transformers built in China (lately).
If the transformer sat idle in the winter power outage and wasn’t tested for water content (condensation) at start-up, it could have been gassing right up until explosion.
on the big ones (345kV) up here in the north, we circulate the oil during cool down and check for water before re-start.
Or, drain and replace.
That and the Chinese thing; they ship them over fully assembled. If inferior equipment was used to save a buck...
would \NOT\ attribute to terrorism...
Yes, condensation buildup and oil contamination is a possibility. I know that industry practice is to keep a low pressure “blanket” of nitrogen on the top of the tank, above the oil level to keep moisture out. positive pressure prevents the vent from “inhaling” moist local air. But it it was off line for an extended period of time, and if nobody checked the nitrogen gas pressure (we used to change out tanks regularly at stations) it could have gone to 0 PSI, then vacuum could occur any time it gets cool (at night or winter).
They’ll analyze the issue at the company that owns it (I think it’s Centerpoint energy, but not sure) to see the root cause. But first, they need to put out the fire and restore all the customers from other sources.
Oh, it looks like the high voltage side of the 2 transmission voltage transformers is quite possibly 345 kV. They use that in Texas quite a bit. Can’t tell from google maps what the low side is, but probably 138 kV or 115 kV, whichever is more customary in that area.