IV--Combined Reliability and Economy in Operation of Large Electric Systems Chicago District

The paper outlines the load characteristics, generating stations, and transmission lines of the Chicago territory and particularly the power supply of Chicago proper. The economics of the scheme of supply are discussed from the points of view of interchange energy agreements, comparative increment fuel costs of generating stations, increment losses of transmission lines, load schedules, remote metering and load dispatching, economics of 550-to 650-lb. units, automatic frequency regulation, control of wattless mva. voltage and phase angle. The reliability of the system is outlined with respect to the design of generators, switchgear, transmission lines and cables, relay protection, methods of operating, and reserve capacity. From the experience gained in the Chicago territory conclusions are drawn as to the policies of economy and reliability which have been adopted in operating the system.