C. Truman Hibbard and the Invention of Automatic Control for Synchronous Motors

The synchronous motor was created in 1869, nearly twenty years before the invention of the induction motor. Yet, by the beginning of the 20th Century the induction motor had achieved a maturity, such that it was being widely applied in industry. The synchronous motor, despite unique features, did not reach a similar degree of acceptance until the eady 1920's. A half-century was required to evolve suitable starting ability by symbiosis with the induction motor, and further to exploit synchronous motor advantages for power factor correction, and finally to remove the limitations ofmanual starting by development of automatic control for synchronous motors. This article gives some historical background, and recounts the part taken by C. Truman Hibbard in the progres of the motor after 1912. As Chief Engineer of the Electric Machinery Manufacturing Company, he contributed to the development and promotion of synchronous motors and was the inventor of automatic control for the motor.