EMP effect on electrical transformers

Dr. Jeff Masters. 3 Apr 2009. A future Space Weather catastrophe: a disturbing possibility.

We have the very real possibility that a geomagnetic storms of an intensity that has happened before–and will happen again–could knock out the power to tens of millions of Americans for multiple years. The electrical grids in Europe and northern Asia have similar vulnerabilities, so a huge, years-long global emergency affecting hundreds of millions of people and costing many trillions of dollars might result from a repeat of the 1859 or 1921 geomagnetic storms.

A May 2013 study by AER and Lloyd’s (available here) concluded that the total US population at risk of extended power outage from a Carrington-level storm is between 20-40 million, with durations of 16 days to 1-2 years. The duration of outages will depend largely on the availability of spare replacement transformers. If new transformers need to be ordered, the lead-time is likely to be a minimum of five months. The total economic cost for such a scenario is estimated at $0.6-2.6 trillion USD.

Increased vulnerability to geomagnetic storms?
On the other hand, the evolution of open access on the electrical transmission system in recent years has resulted in the transport of large amounts of energy across the power system in order to maximize the economic benefit of delivering the lowest-cost energy to demand centers. The magnitude of power transfers has grown, and the increased level of transfers, coupled with multiple equipment failures, could aggravate the impacts of a storm. For example, the long distance between Hydro-Quebec’s hydro-generation stations and load centers is one of the factors that is believed to have contributed to its crash during the 1989 Superstorm. In a remarkable 2008 National Academy of Sciences report, “Severe Space Weather Events–Understanding Societal and Economic Impacts Workshop Report”, John Kappenman of Metatech Corporation theorizes that a future repeat of the Carrington event or the 1921 geomagnetic storm could result in catastrophic failure of large portions of the electrical grid that would last for years, costing 1-2 trillion dollars in the first year, and putting million of lives at risk. Full recovery from the event would take 4-10 years. The possible extent of a power system collapse from a repeat of the great magnetic storm of May 14-15, 1921–the second strongest geomagnetic storm in recorded history (Figure 2)–shows that a large region of the U.S. with a population of 130,000,000 might be affected.

The strong electric currents that would flow through the the electrical grid during a repeat of the Carrington event are likely to cause melting and burn-through of large-amperage copper windings and leads in electrical transformers. These multi-ton, multi-million dollar devices generally cannot be repaired in the field, and if damaged in this manner, they need to be replaced with new units. There are only a handful of spares in reserve, so most of the region affected by the collapse would remain without power until new transformers could be custom built. During the March 13, 1989 Superstorm, geomagnetic-induced currents (GICs) melted the internal windings of a 500kV transformer in the Salem Nuclear plant in southern New Jersey (Figure 3). The entire nuclear plant was unable to operate until this damaged transformer was replaced. Fortunately, a spare from a canceled nuclear plant in Washington State was available, and the Salem plant was able to reopen 40 days later. Had the spare not been available, a new custom-built transformer would have been required, potentially idling the power plant for years. The typical manufacture lead times for these transformers are 12 months or more. According to a January 2009 press release from Metatech, Inc., 300 Extra High Voltage (EHV) transformers in the U.S. would be at risk of permanent damage and require replacement in the event of a geomagnetic storm as intense as the 1921 or 1859 events. Here’s where it gets really scary. According to the press release:

* Manufacturing capability in the world for EHV-class transformers continues to be limited relative to present market demand for these devices. Further, manufacturers would be unable to rapidly supply the large number of replacement transformers needed should the U.S. or other power grids suffer a major catastrophic loss of EHV Transformers.
* Manufacturers presently have a backlog of nearly 3 years for all EHV transformers (230 kV and above). The earliest delivery time presently quoted for a new order is early 2011.
* Only one plant exists in the U.S. capable of manufacturing a transformer up to 345 kV. No manufacturing capability exists in the U.S. at present for 500 kV and 765 kV transformers, which represent the largest group of At-Risk transformers in the U.S.

January 2009 press release from Metatech, Inc., “An Overview of the National Academy of Sciences Report on Severe Space Weather and the Vulnerability of US Electric Power Grid”.

August 2008 Scientific American article, “Bracing the Satellite Infrastructure for a Solar Superstorm”.

2008 National Academy of Sciences study, , “Severe Space Weather Events–Understanding Societal and Economic Impacts Workshop Report”

March 2009 newscientist.com article on Space Weather threats.

Excellent 2007 lecture by John Kappenman of Metatech Corporation, “Electric Power Grid Vulnerability to Geomagnetic Storms” (50 minutes).


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