Newspaper article The Christian Science Monitor

The Wyman Dam Mystery, Revealed

Newspaper article The Christian Science Monitor

The Wyman Dam Mystery, Revealed

Article excerpt

We thought you'd enjoy this response to a question posed in a John Gould essay: What is the electrical-generator doohickey that makes clocks run on time?

Dear Editor,

I am writing in response to John Gould's column of June 21 {"Two Electrifying Ideas That Never Lit Up the World," Page 17}, in which he tells of a disappointment. He had not heard back from his electric utility, which had promised him a letter more than 60 years ago describing a device at Wyman Dam in Moscow, Maine, that controlled the pulse of power to keep clocks on time.

When I started this job of responding to customers' questions a few years ago, I had no idea there was an unanswered one going back to the 1930s.

We supply electricity at 60 cycles AC. This means that the voltage alternates between a positive and negative charge 60 times a second. The speed at which the generator rotates determines the cycles per second. Clocks with small synchronous motors are very sensitive to the frequency of the electricity supplied. If it is less than 60 cycles a second, they run slow. If it is more than 60 cycles a second, they run fast.

The generators at Wyman Dam are tied into a regional power grid, the New England Power Pool (NEPOOL). Frequency on the grid is monitored by NEPEX, the operating arm of NEPOOL. It sends signals via microwave to generating stations around New England to increase or decrease power to the generators to maintain proper frequency.

When the generator shaft at Wyman Dam is rotating at 138.5 revolutions per minute, the generator puts out 60-cycle current. To change the frequency, the governor (not John Reed, the former Maine governor Mr. Gould referred to) on the water turbines is adjusted to increase or decrease the flow of water, which in turn spins the generator faster or slower.

Dana Sullivan in Hydro recalls in the 1970s seeing a device that monitored frequency at Wyman and made automatic adjustments to the governors. It was tied into the National Bureau of Time Standards via the phone lines. Perhaps this is what Mr. Gould should have been shown on his tour in the 1930s.

Uncle Sam, as the official timekeeper, runs the master atomic clock in Washington. …

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