A record-breaking heatwave caused a significant infrastructure disruption, knocking out electricity and phone services for millions of customers across a vast region stretching from Canada to the Southwestern United States.
The widespread power failure highlighted the vulnerability of electrical grids during extreme weather conditions.
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On July 2, 1996, California and the coastal Pacific Northwest imported extensive hydropower from the inland Pacific Northwest and Canada and thermal power from the eastern Rockies.
North American grid managers regularly simulate possible grid conditions to plan for contingencies, but had not investigated these particular long-range power flows.
Although managers did not realize it, the system operated close to a dynamical singularity, and grid response to a small reactive power deficiency in the Idaho area would involve very large and very rapid voltage changes all across the system.
A brief grounding and misconfigured relay then effected the deficiency, and protective devices separated large segments of the grid faster than operators could react.
The power failure affected parts of Alberta and British Columbia in Canada, western Mexico, as well as Idaho, Montana, Utah, New Mexico, California, and Arizona, affecting more than two million people. Most power was restored in an hour or two.
The following day, transmission lines disconnected in a similar manner, but precautionary limits imposed on the transmission system following the July 2 blackout prevented cascading failure.
President Bill Clinton directed the United States Department of Energy to investigate the reasons for the widespread power outage and whether it could have been prevented.
I was also writing to Nicola Nash of Fotherigills seeds as follows: 'Dear Nicola, I write in confirmation of our telephone conversation today, in which you assured me that our terms of trade for Redgrave Account 17894 were in accordance with the code printed on our order document (pink copy) of 5/X/SC/50.00/0.00 ie Stock Credit at 50% discount, whereby we could return unsold stock at the end of the season for cash refund or credit against next season’s order.
These terms are as agreed with your representative at the beginning of this year but in contrast to those printed on the order document.'