City blackout leaves MIT in the dark


Physical Plant workers struggled to bring back power to the campus after a cable fault in Cambridge Electric's power distribution system caused a blackout on August 7. But their efforts were hampered when a second off-campus incident--a fatal manhole explosion near the intersection of Hampshire and Portland Streets that killed one Cambridge Electric employee and injured four other people--put out the lights on campus a second time.

The problems began with bus tie cables running between two of Cambridge Electric's power stations, Kendall and Putnam, which distributes power to parts of MIT's campus. When these cables failed, they initiated a domino effect of power overloads followed by circuit-tripping that went from Kendall to Putnam to the gas turbine at MIT's cogeneration facility, and finally to the largest of MIT's 30 emergency diesel generators.

The unusual chain of events left Physical Plant employees working in the dark to restore power at the Institute.

"There were some extraordinary things done that night," said William Wohlfarth, senior electrical engineer in Physical Plant. "It's hard enough when you have normal power loss and you're working with emergency power. It's much more difficult without emergency power. We were using flashlights, opening up drawings and trying to diagnose the problems. Quite a few of us had beads of sweat on our brows that night."

Although power was disrupted on the campus for about four hours, relatively few problems have been attributed to the outage. Physical Plant received no reports of major disasters, only one report of significant experimental loss, and very few reports of minor problems. Mr. Wohlfarth attributes this to a charitable attitude within the MIT community.

"I think because of the seriousness of the damage within Cambridge, including the fatality, there are probably a lot of folks who haven't called to complain about problems on campus. It's hard to complain about a loss of data when a guy got killed," said Mr. Wohlfarth.

The cascading overloads initially resulted in a total power loss on campus from 5:45-7pm. Power was restored, only to be lost again minutes later after the fatal accident. Electricity was once again fully restored to MIT by 10pm, but a control circuit board of the cogeneration facility's gas turbine had been damaged, forcing the campus to rely solely upon power from Cambridge Electric until late Friday evening, Aug. 8, when the damaged parts were replaced.

The cogeneration plant normally supplies between 70 and 90 percent of the campus's power. The remainder is purchased directly from Cambridge Electric and comes from the Putnam station. MIT's largest emergency diesel generator, an older model that was unable to produce the amount of power needed both to maintain the central utility plant at a necessary minimal level and provide power to the campus, is one of the things that Physical Plant will look at closely in the aftermath of the outage.

"We'll be looking at the emergency generator to see what should be done. It may need to be replaced or overhauled. We'll also be looking at the protective relaying system between MIT and Cambridge Electric, as well as ways to improve our response procedures," said Mr. Wohlfarth.

Many buildings on campus have their own emergency power supplies, but those that rely on the central campus emergency generator were suddenly very dark, making it difficult for people just to find their way out.

Capt. John Driscoll of Campus Police said a dozen officers helped out during the emergency, including three patrol officers who were diverted from a training exercise.

"We were fielding hundreds of calls from people wondering what was wrong. We began to patrol the campus with flashlights to make sure that people could safely exit the buildings, and to help Physical Plant employees get into the buildings and find their way around. We also had to make sure that no larcenies occurred," he said.

"This was a very unique situation. You get used to the street lights and traffic lights and what have you, and without them, it's really dark," Capt. Driscoll said, calling the lack of serious problems associated with the blackout "miraculous in a way."

A version of this article appeared in MIT Tech Talk on August 13, 1997.


Topics: Campus services

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