Sunday, August 17, 2003

Worst ever power cut hits North America

14:34 15 August 03
Damian Carrington and Jeff Hecht

The worst power cut the world has ever seen - a loss of 62,000 megawatts - struck eastern North America on Thursday. By early Friday morning about two-thirds of the electricity lost had been restored, but the cause of the massive outage remains unknown.

The failure hit suddenly at 1611 EDT and about 50 million people in cities from New York to Toronto to Cleveland, Ohio are thought to have been affected. People were trapped in subway trains and elevators in New York and police officers were mobilised overnight to prevent looting.

Many areas are now regaining power but some, for example in Detroit, may have to wait until Sunday. The New York City electricity company Con Edison urged "customers with power to refrain from using major appliances such as washers, dryers and air conditioners".

Numerous suggestions have been cited as the cause for the blackout, but the US authorities have ruled out terrorism and a computer worm spreading across the internet. A key problem was the failure of the high-voltage wires connecting the region's power systems. "The disturbance appears to have been caused by the loss of several major transmission lines in the upper Midwestern United States, which caused additional lines to go out of service," said the North American Electric Reliability Council.

The trigger for this cascade of failures was suggested to be a fire or a lightning strike at a power station near Niagara Falls in New York state. But the Canadian prime minister's office also suggested a failure at a nuclear power plant in Pennsylvania might have been to blame.

Terrible luck

Daniel Kirschen, an electricity supply expert at UMIST in Manchester, UK, believes there are two main possibilities. The first is "terrible bad luck" - i.e. that more than one damaging event like a lightning strike or substation fire struck in quick succession. Single events of this type are common and are usually accommodated without difficulty.

The second possibility is that the safety margin that should always protect the grid against overload was exceeded. "It was a very hot day yesterday, meaning the system was very loaded and therefore less stable," Kirschen told New Scientist.

The US and Canada, being large countries, require long power lines, which are inherently less stable than shorter ones. Their continental climate also means that lighting strikes are much more common than in Europe.

The liberalisation of the electricity market in the US could be a factor too, says Kirschen, as power is now bought and sold over longer distances. This means local transmission systems are placed under greater strain. On Friday, critics blamed under-investment in US electricity transmission infrastructure, saying that demand had increased at twice the rate of capacity over the last 10 years. This would place the grid nearer its breaking point.

The last widespread power cut in the region was in 1965. The electricity supply was completely restored within 14 hours, but it took six days to locate the cause. This was a single faulty relay in Canada that triggered a series of overloads.

14:34 15 August 03

பதிந்தது <-குருவிகள்-> at 7:34 pm

0 மறுமொழிகள்:

Post a Comment

இந்த இடுகைக்கு மேலதிக தொடுப்புச் செய்ய:

Create a Link

<<முகப்புக்குச் செல்க