Abstract :
Great progress has been made. Interconnection between independent systems is primarily a protective measure, but the greatest economic benefits have been realized when the interconnections have been made by subsidiary companies of one holding company. The capacity of tie lines and the amount of power interchanges has developed greatly. The size of generating units has increased, as has the size of power plants, resulting in lowered cost per kw. The problem of satisfactory voltage and power factor control has increased in complexity as has that of system load dispatching. While much improvement has been made in oil circuit breakers, they still leave much to be desired. Interconnection has made possible more economical operation of existing plants and has resulted in the use of a larger proportion of the available water on systems combining steam, storage, and run-of-river hydroelectric plants. Long-time forecasting of load and rainfall conditions is important in economical system planning. The 110-kv. and 154-kv. line construction is discussed; also the value of ground wires and lightning arresters. The growing importance of carrier current for supervisory control and communication and their application are reviewed.
