A switch is thrown. A slight anomoly registers with the main computer incharge of power production, and adjustments are made. Within 10 mintues 37 more adjustments are made. In the next five minutes there are so many instructions processing that the computer takes control of the secondary processor that handles the mondane operations of the power plant. It needs more control. Its getting input and readings from every substation now, and the readings make no sense.
A quick analysis of the readings and the computer makes a quick series of adjustments. There is no way for it to know that it is now causing more of the trouble than the 'anomolies'.
5:17 - PM
The power flickers, causing a few groans around the city.
5:18 PM
The adjustments have resulted in a power surge that renders 5 substations useless. The computer, still trying to cope with the changes and irratic readings, tries to reboot the systems-- and finds it can't.
5:19 PM
A power surge, built up over the last 19 minutes practically welds the computer into place, then fries it and the lines coming in and out of the building.
5:20 PM
An automatic call to the fire department is cut off in mid stream.
Darkness descends on Seattle as everthing comes to a grinding halt.