SPECULATION: Could temporally transient and spatially isolated magnetic field fluctuations be causing the transformer failures?

Transformer Failure Modes

The following failure scenarios are given by the International Association of Inspection Engineers, [link to www.bplglobal.net] (listed in order of frequency). I've also included my own thoughts on the probability that each failure mode might explain the recent string of failures (in italics).

Insulation failure

Insulation failures were the leading cause of failure in this study. This category excludes those failures where there was evidence of a lightning or a line surge. There are actually four factors that are responsible for insulation deterioration: pyrolosis (heat), oxidation, acidity, and moisture. But moisture is reported separately. The average age of the transformers that failed due to insulation was 18 years.

This failure mode would require all of the transformers that have blown to have the same degree of insulation deterioration at nearly the same time. This seems highly unlikely unless they all overheated - but that would imply that the feed voltage to all of these transformers was higher than the design voltage. This might be somewhat reasonable if there were a computer virus affecting power plant outputs. The other possibility is solar activity. However, solar data shows that the sun, although quite active, is not spitting out anything extreme in terms of coronal mass ejections.

Design/Manufacturing failure

This category includes conditions such as: loose or
unsupported leads, loose blocking, poor brazing, inadequate core insulation, inferior short circuit
strength, and foreign objects left in the tank. In this study, this is the second leading cause of
transformer failures.

This failure mode appears to be highly unlikely although it would be interesting to know the make/model of all these transformers that have failed and when they were installed.

Oil contamination failure

This category pertains to those cases where oil contamination can be established as the cause of the failure. This includes sludging and carbon tracking.

This failure mode also appears to be highly unlikely.

Overloading

This category pertains to those cases where actual overloading could be established as the cause of the failure. It includes only those transformers that experienced a sustained load that exceeded the nameplate capacity.

This goes along with insulation failure - not likely but possible.

Fire/explosion

This category pertains to those cases where a fire or explosion outside the transformer can be established as the cause of the failure. This does not include internal failures that resulted in a fire or explosion.

Obviously not the case.

Line surge

This category includes switching surges, voltage spikes, line faults/flashovers, and other T&D abnormalities. This significant portion of transformer failures suggests that more attention should be given to surge protection, or the adequacy of coil clamping and short circuit strength.

Again, very similar to insulation failure and overloading.

Maintenance/operation

Inadequate or improper maintenance and operation was a major
cause of transformer failures, when you include overloading, loose connections and moisture. This category includes disconnected or improperly set controls, loss of coolant, accumulation of dirt & oil, and corrosion. Inadequate maintenance has to bear the blame for not discovering
incipient troubles when there was ample time to correct it.

Not a likely failure mode.

Floods

The flood category includes failures caused by inundation of the transformer due to man-made or natural caused floods. It also includes mudslides.

Obviously not the case here.

Loose connections

This category includes workmanship and maintenance in making
electrical connections. One problem is the improper mating of dissimilar metals, although this has decreased somewhat in recent years. Another problem is improper torquing of bolted connections. Loose connections could be included in the maintenance category, but we customarily report it separately.

Not a likely failure mode.

Lightning

Lightning surges are considerably fewer in number than previous studies we have published. Unless there is confirmation of a lightning strike, a surge type failure is categorized as “Line Surge”.

There was a storm in the Ft. Worth area when the transformers failed. I don't think this was the case for the Wisconsin and Las Vegas explosions. Someone correct me if I am wrong. However, even with the Ft. Worth explosions it wasn't a single isolated explosion as one would expect with a lightning strike.

Moisture

The moisture category includes failures caused by leaky pipes, leaking roofs, water entering the tanks through leaking bushings or fittings, and confirmed presence of moisture in the insulating oil. Moisture could be included in the inadequate maintenance or the insulation failure
category above, but we customarily report it separately.

Not a likely failure mode.

Speculation

I do not believe these transformer failures are caused by solar activity (at least, not any type of activity that we routinely measure). This pretty much leaves insulation failure or overload as the only failure mode above that makes any sense. Given the number of failures we have observed over the last few days, the only explanation that seems appropriate is that the power output and distribution controls have been compromised by a computer virus.

However, there is another possible explanation in my mind but it is far more speculative than anything else presented here. The heart of a transformer is the iron core which has a high magnetic permeability and uses the magnetic flux generated by the high voltage windings to induce a low voltage in the other set of windings. If there were spatially isolated and temporally transient fluctuations occurring in the geomagnetic field (or some extraterrestrial magnetic field) transformers would be the first place this would be expected to manifest itself. The iron cores have such a high magnetic permeability that the field generated within the volume of the core could be drastically changed by magnetic fields of relatively modest strength. The variation of the magnetic field within the core would influence the input and output voltages in the transformer. If the effect were large enough you might see overloading of the transformer which would cause it to fail.

I have no idea if this hypothesis is reasonable. Even if it is correct, I don't know what would be causing magnetic field fluctuations to occur in a way that is spatially isolated and temporally transient. Yet, it is still thought-provoking. There is certainly SOMETHING causing these failures. The question is what? It is beyond our normal everyday experience to observe this kind of phenomenon.