Design of an electronic frequency changer

THIS paper discusses the circuit arrangement and design features of an electronic-frequency-changer station for interchanging power between the Carnegie-Illinois Steel Corporation's 25-cycle system and their 60-cycle system. The transfer of power by rectification and inversion has been discussed in a companion paper by Cramer, Morton and Darling.¹ The reader should consult their paper to obtain a clear picture of the power flow from alternating to direct current in the rectifier and from direct to alternating current in the inverter. The operating requirements as presented in the Cramer, Morton and Darling paper may be summarized as follows: 1. The direction of power flow must be reversible at will. 2. The load must be independent of system frequency and small variations in system voltage. 3. It must be possible to atijust the load to any desired value for either direction of power flew.