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It's often said that a strong solar storm can burn out the biggest transformers which would take months to replace.

If these transformers are so critical, I can't believe they don't have any safety measures. Eg. cutting them off from the grid when they overheat to cool them down, so we would have a short blackout instead of months without elecricity.

  • that train of thought is why insurance companies are so rich. Fear of unlikely events occurring. – Sickest May 6 '15 at 22:39
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    They do have safety measures. The problem is that it takes time for the safety measures to act -- you can't just turn off a 330KV electric line the way you can a light switch. – Mark May 6 '15 at 23:48
  • There's no such thing as cutting them off quickly. Look around You-Tube, you'll find some videos of some of the big switches opening under load--the current just flows through the air instead for a while. It's quite dramatic, not to mention pretty hard on the equipment. – Loren Pechtel May 8 '15 at 2:05
  • @LorenPechtel There are various techniques to prevent arcing. – Calmarius May 8 '15 at 8:10
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NASA says:

Multi-ton transformers damaged by such a storm might take years to repair.

This effect has been observed on a small scale (nasa.gov):

A similar flare on March 13, 1989, provoked geomagnetic storms that disrupted electric power transmission from the Hydro Québec generating station in Canada, blacking out most of the province and plunging 6 million people into darkness for 9 hours; aurora-induced power surges even melted power transformers in New Jersey.

[...]

Another Carrington-class flare would dwarf these events.

The Department of Homeland Security issued a risk assessment in 2011 that said (p. 3):

Recent estimates state that 300 large extra-high-voltage transformers in the United States would be vulnerable to geomagnetically induced currents. Damage to an extra-high-voltage transformer from geomagnetically induced currents could take months or even a year to repair and cost in excess of $10 million.

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    correct. Combine that with the fact that they can't be held in spare because each is different (unlike the small ones, where some spares are kept) and the fact that there are very few manufacturers left because there's not a lot of demand during normal operations (thus lead times for a very large order would be long) and you have your reasons for the long time needed to repair a large scale outage. – jwenting May 8 '15 at 14:23
  • @jwenting: Why would "each is different" prevent spares from being kept? Even if each transformer site requires a transformer specially tailored to the location, that wouldn't preclude the sites keeping spares for that specific location. – Sean Mar 20 at 2:53
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    @Sean cost and size. These aren't the little boxes sitting on poles in your street we're talking about. These are machines the size of a small house. Even an emergency one that could be shipped in on a lorry to provide emergency power to an area awaiting rebuilding of the permanent transformer needs a oversized load transporter to move around. – jwenting Mar 21 at 4:52
  • @jwenting: Hence why I was suggesting keeping the spares on-site, so you wouldn't have to truck them in. – Sean Mar 22 at 2:44
  • @Sean that'd not work in case of a strong enough EMP as it can knock out the on site spare as well. You'd need to store it disassembled somewhere, and hope the component parts don't get damaged. – jwenting Mar 22 at 4:34

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