The Big Allis generator sixty years ago 

Think back to the 1965 electrical power blackout in the Northeast United States of just over sixty years ago. It was on November 9, 1965. There was a huge consequence for Consolidated Edison in New York City.

Their power-generating facility in Ravenswood had been equipped with a generator made by Allis-Chalmers, as shown in the following screenshots.

Figure 1 Ravenswood power generating facility and the Big Allis power generator.

That generator was the largest of its kind in the whole world at that time. Larger generators did get made in later years, but at that time, there were none bigger. It was so big that some experts opined that such a generator would not even work. Because of its size and its manufacturer’s name, that generator came to be called “Big Allis”.

Big Allis had a major design flaw. The bearings that supported the generator’s rotor were protected by oil pumps that were powered from the Big Allis generator itself.

When the power grid collapsed, Big Allis stopped delivering power, which then shut down the pumps delivering the oil pressure that had been protecting the rotor bearings.

With no oil pressure, the bearings were severely damaged as the rotor slowed down to a halt. One newspaper article described the bearings as having been ground to dust. It took months to replace those bearings and to provide their oil pumps with separate diesel generators devoted solely to maintaining the protective oil pressure.

So far as I know, Big Allis is still in service, even through the later 1977 and 2003 blackouts, so I guess that those 1965 revisions must have worked out.

John Dunn is an electronics consultant, and a graduate of The Polytechnic Institute of Brooklyn (BSEE) and of New York University (MSEE).

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