Replies

Mayor Bloomberg saying on CNN that the Con Ed shutdown was normal after overload of Niagara Mohawk station in Canada. NO fire at Con Ed. Normal burnoff producing smoke from smokestack. NO evidence whatsoever of any terrorism. People should go home, open windows, drink water.

I must say Bloomberg is exuding calm here. Very reassuring. Says there is not panic, hospitals have emergency power.

WMAL: Niagara Mohawk power grid may be overloaded. ""So Con Ed in Manhattan blows up?""

Actually, it could be the other way around. Con-ed is running on the edge, loses a key component of its system. This causes power to route itself through Niagra Mohawk's grid to other lines leading into NYC. Those lines trip, causing a cascading outage in the city.

Once the city loses power, the system's generation overspeeds due to the loss of load, causing generators to trip off line through their protective relaying. Generators trip in the most inopportune places, possibly including Cleveland, Detroit, Ottowa, and Toronto. The loss of generators causes more overloads and those overloaded lines in turn trip causing more loss of load.

The gyrations continue for a few minutes until everything interconnected is dead, or the load/supply equation achieves something close to equallibrium. That appears to be what happened, as although we saw frequency disturbances in the south, there are no major outages in this part of the country and we in Tennessee are rather tightly connected to the rest of the eastern grid.