A Lemon Named Big Allis

Almost exactly a year ago, the Consolidated Edison supergenerator known as "Big Allis" short-circuited, melting her metal insides and reducing Con Ed's electric power supply to New York City by 14%. "Brownouts" followed --reductions of power that dimmed lights and left New Yorkers chagrined. Con Ed engineers toiled on the generator, built by Allis-Chalmers, round the clock. After six months and 80,000 man-hours of work, Big Allis was "on line." But not for long. Within 87 minutes she conked out for four more months.

Tripping Out. Last week, after only 35 days of operation, Big Allis in the jargon of power engineers "tripped out" again--and again corridors darkened in many Manhattan buildings as residents tried to conserve power for such needs as air conditioning and elevators. After the million-kilowatt generator shut herself down. Con Ed reduced power to the city by 5% and purchased power from utilities in the eastern U.S. and Canada to make up for the shortage. New Yorkers alternately worried with affection about Big Allis and cursed the day they became dependent on her.

What caused the breakdown in Con Ed's most sophisticated piece of generating equipment? Engineers say Big Allis shut down because she was vibrating due to a faulty bearing connected to her high-pressure turbine. Though they have discovered the problem, they do not know why the bearing failed.

It is possible that the six-year-old, $168 million generator keeps breaking down because she simply is too big and too complicated. After the 1970 trip-out, for example, engineers had to remove each of the 188,000 layers of sheet iron composing Allis' 325-ton stator, which surrounds the rotor, then rebuild the stator in an air-conditioned, dust-free enclosure, because of the sensitivity of the equipment.

Joseph Swidler, chairman of the New York State Public Service Commission, has a simpler suggestion for the cause of Big Allis' ills: "It's a lemon."

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