Telechron - Henry Warren: The Synchronous Motor and The Master Clock

Henry Warren: The Synchronous Motor and The Master Clock

Henry Warren established the company in 1912 in Ashland, Massachusetts. Initially, it was called "The Warren Clock Company," producing battery-powered clocks. These proved unreliable, however, since batteries weakened quickly, which resulted in inaccurate time-keeping. Warren saw electric motors as the solution to this problem. In 1915, he invented a self-starting synchronous motor consisting of a rotor and a coil, which was patented in 1918. A synchronous motor spins at the same rate as the cycle of the alternating current driving it. Synchronous electric clocks had been available previously, but had to be started manually. In later years, Telechron would advertise its clocks as "bringing true time," because power plants kept the frequency of the alternating current perfectly constant at 60 Hz. But such constancy did not yet exist when Warren first experimented with his synchronous motors. Irregularities in the frequency of the alternating current led not only to inaccurate time-keeping but, more seriously, to incompatible power-grids in the US, as power could not readily be transferred from one grid to another. In order to overcome these problems, Warren invented a "master clock," which he installed at the Boston Edison Company in 1916. This clock had two movements, one driven by a synchronous motor connected to the current produced by the power plant, the other driven by a traditional spring and pendulum. The pendulum was adjusted twice a day in accordance with time signals received from the Naval Observatory. As long as the hands of the electric clock, powered by a 60 Hz synchronous motor, moved along perfectly with those of the "traditional" clock, the power produced by the electric company was uniform. In Electrifying Time, the standard work on Telechron clocks, Jim Linz writes that "in 1947, Warren Master Clocks regulated over 95 percent of the electric lines in the United States."

It is interesting to note, then, that the uniformity of alternating current in the US, which was necessary to build large power-grids, was initially ensured by a very traditional clock system. Furthermore, Henry Warren invented his master clock at first simply in order to guarantee that his synchronous clock motor would provide accurate time.