With nearly 40 percent of its power supplied lost, apparently to lightning strikes, Con Ed averted a systemwide power failure yesterday by quickly cutting voltage, imposing limited blackouts in Westchester and firing up reserve generators.
130,000 customers in Westchester and a sliver of the north Bronx were blacked out for an hour or more, 80,000 deliberately to cut back the demand on the utility system. Service to nearly all was restored in an hour. The crisis was the most severe since July 13-14 when New York and Westchester were plunged in darkness for up to 25 hours and spawned widespread looting, arson and other problems.
Even before the emergency struck yesterday, Con Ed had declared an internal storm watch under which reserve generators were prepared for use and other steps were taken.
Lightning strikes occurred about 3:30 in the vicinity of Staten Island and near Ramapo New York and sent surges through the transmission lines that tripped circuit breakers and shut down four generating plants. To cope with the sudden lose of 2100 megawatts (38% of the 5,500 megawatts being supplied on the system at the time – the utility first implemented at 8% voltage reduction to all of the three million customers on the system. 80,000 Westchester customers were cut off (another 50,000 were affected by power failures caused by down lines).
“The reports we received were that they were the heaviest thunderstorms ever seen in this area.”
During the July blackout, more than a score of gas turbines representing almost 2000 megawatts of generating capacity were not manned at night, to cut costs, and were thus unavailable for an emergency. Since the July blackout the turbines have been manned around the clock and tested regularly.
In July a Con Ed spokesman had labeled the blackout “an act of God.”
excerpt from Robert McFadden NYT 9/27/77