Con Edison revealed Monday afternoon that a malfunctioning protection system for parts of the electrical grid may have been the root cause for Saturday’s blackout that affected 72,000 Manhattan customers.
The utility offered the initial findings of its investigation into the blackout, which took out power for the Upper West Side and midtown, and said the relay protection system at its West 65th Street substation failed to contain a 13,000-volt distribution cable that stopped working Saturday night. The protection system, “detects electrical faults and directs circuit breakers to isolate,” however, it didn’t work when the cable stopped working, according to the utility.
“The failure of the protective relay systems ultimately resulted in isolation of the fault at the West 49th Street transmission substation, and the subsequent loss of several electrical networks, starting at 6:47 p.m.” Con Ed said in a statement.
The utility said it was able to restore power quickly to the affected parts of Manhattan, by midnight, and immediately began its investigation. Con Ed said it is still investigating the incident and will provide more information when it becomes available.
Several elected officials, including Mayor Bill de Blasio and Gov. Andrew M. Cuomo, have called for an independent investigation into Con Ed to determine how the blackout was able to affect such a large portion of the city.
"While I appreciate that Con Edison released their preliminary findings so quickly, I am troubled that one of the few factors Con Edison initially ruled out, the 13,000-volt cable, has been determined to be the catalyst of the outage," de Blasio said in response to Con Ed’s update Monday. "Our city cannot be left in the dark like this ever again, and we will continue to push Con Edison for a full accounting of this incident to ensure they are taking necessary steps to protect all New Yorkers."
Cuomo gave several media interviews Monday to express his frustration with the utility. He told WNYC’s Brian Lehrer that the blackout was a serious public safety risk and he threatened to issue fines to Con Ed or revoke its franchise.
“This is not a God-given right, and if they don’t perform well, they can be replaced,” he said.