Usually it is, if you are looking for it.
If you are doing regular sampling of the transformer’s oil you can detect the gases given off from the dielectric break down caused failing winding insulation and internal arching.
If you find it early you can take the failing transformer off and replace it before failure happen.
I work for an electric utility and we sample our big transformers on a regular bases.
Most transformer failures are caused by wild life. Four legged but occasionally two legged as well.
I’ve made a list of medium voltage events and their causes. 98% are explained by a list of about 10 explicit causes, generally colloquial. These are typically provided within 24 hrs of the event, but generally, the observed damage are secondary failures caused by more elusive sources. The following are what tends to satiate the uninformed.
Bird Strike
Rodent gnawing insulation
Pinhole in insulation
Gopher digging earth in transformer
Solar Flares
Lightning Strike
Wind induced wire slapping
Mylar Helium Balloon
Tree Limb falls on OH lines
Leaking Oil from transformer
Mechanical Failure of Vacuum Switch
Construction accident nicking an underground line.
Car accident hits utility pole.
etc
The ConEd event is interesting because backup generators didn’t energize at LaGuardia. Their ATS should have provided near seamless power to the tenants. Even if the circuit protection isn’t adequately coordinated, the damage likely would have been localized and protection relays and fusing would have kept the event to a very short duration, way less than 1 sec.
Another event in Kenner, Louisiana, on the same evening also appears anomalous. Looks like a reversed phasing issue or crossed lines as a fireball repeatedly travels down the transmission line, with other services down-line showing evidence of over-voltage failures, ...perhaps a neutral being energized by a medium voltage line frying all the local panel-boards and metallic grounded surfaces.