February 3, 2011
Becky Bray, a San Angelo mother of two, said she thought the power would be off Wednesday for about 15 minutes, the length of time Texas electric companies said the controlled outages would last.
Michael Giesselmann, a professor and chairman of the Electrical and Computer Engineering Department at Texas Tech, said that as the demand for electricity increases, the power must increase.
If the power does not increase proportionally with the demand, the frequency of the transmitted electricity drops to the point that the power station shuts itself down, so that the station trips like a breaker. An uncontrolled blackout results from the domino effect of stations shutting down.
“If the load is going up more than you expect and you don’t have the generation, you have to shed some load so you don’t have your system totally collapse,” Giesselmann said.
ERCOT said the grid lost 7,000 megawatts of capacity.
Giesselmann estimated one megawatt could support about 400 homes.