ConEd: Failed relay systems, not transmission equipment, caused NYC blackout

Utility Dive: ConEd says its analysis of Saturday's blackout will continue, but preliminary conclusions point to the failure of a system designed to detect electrical faults, and then direct circuit breakers to isolate and de-energize those faults.

"The relay protection system is designed with redundancies to provide high levels of reliability," ConEd said in a statement Monday afternoon. In this case, the utility said, primary and backup relay systems failed to isolate a faulted 13 kV distribution cable at West 64th Street and West End Avenue.

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