Electronic frequency changer used as nonsynchronous tie between A-C power systems

EARLY in 1943 a 6,667-kw electronic frequency changer, using mercury-arc rectifiers, was installed in the Gary Sheet and Tin Mill of the United States Steel Corporation, at Gary, Ind., to provide a nonsynchronous tie between the 25-cycle and 60-cycle power systems, for the controlled interchange of power in either direction.1 All the 25-cycle power is generated in the steel company´s plants in the Chicago district. The 60-cycle system is supplied by the steel company´s generating equipment and by the Northern Indiana Public Service Company. The generating capacity of each system is over 200,000 kw.