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Sun Damage

Geomagnetic storms and the limits of human experience.

Fortnightly - June 2012

cluster failures are very unusual, out of the blue.”

In reply, Kappenman said he’d looked at all sorts of causal factors, but found that the greatest correlation of transformer failure tracked geomagnetic storm activity:

“Every heating event takes life out of the insulation, and then that accelerates the possibility of failure, or may work in combination with other stresses that happen to initiate the failure.

“The cause gets fully attributed to that other event, even though the geomagnetic storm was a significant contributing factor.”

Even PJM’s Koza was inclined to agree:

“I’m hesitant to go to medical analogies here. But the transformer has a history, just like our personal health does, and we need to understand that.”

In fact, in the comments PJM filed with FERC ahead of the conference the Foundation for Resilient Societies had noted a research paper written on behalf of Hartford Steam Boiler, a transformer insurer, that surveyed transformer failure claims for the years 1997 through 2001, and found that the claims/loss ratio was about six times higher in 2000 than otherwise. And 2000 was the year in which recorded GIC readings hit a 20-year high, as indicated by EPRI’s Sunburst Network, the collaborative, nearly real-time GIC monitoring system instituted after the 1989 Quebec blackout, and which collects data from participating utilities and then makes the GIC data available online.

The comments from FRS also note a report that analyzed transformer failures after relatively small solar storms in 1982 and 1986, finding higher failure rates in northern areas of the U.S. more susceptible to solar storms.

Interestingly, Kappenman also cited concerns over the occasional big event, coupled with a rapid grid system collapse:

“Again 40-percent over-excitation, which will be caused by a large GIC, [and] the standards now allow only a 10-second duration. They’re very specific on those time limits.

“So if your collapse scenario evolves over tens of seconds, you arguably could have sufficient time there to cause sufficient damage to a large number of exposed transformers.”

In particular, Kappenman brought up the case of the generation step-up transformer at the Salem nuclear plant that failed as a result of the 1989 storm:

“That had to have occurred within about a one-minute interval … and sufficient heat was entrained in that transformer to actually not only burn insulation away, but actually [to] melt phase conductors as well.”

Yet another key problem is the lack of historical data on transformer failures that would allow NERC to formulate models and design standards.

Testifying at the conference was John Houston, senior v.p. for high-voltage delivery and compliance at CenterPoint Energy, serving retail ratepayers in southeast Texas, far away from areas normally thought to be susceptible to GMD effects:

“At CenterPoint 10 years ago … we weren’t worrying about solar storms affecting us.

“So if we had a transformer failure, we wouldn’t have even attributed that to be a possible cause.”

Michael Heyeck, senior v.p. for Electric Transmission America, the AEP venture, regularly holds on to old transformers as spares when new ones are installed, both under the electric industry’s spare