Powerton-crawford 220-kv line-system operating features and terminal design

A 220-kv line, 150 miles long has been constructed between Powerton Station near Peoria, Illinois, and Crawford Station in the city of Chicago. This line will probably operate continuously near the static stability limit and will deliver 150,000 kilowatts to the city from Powerton Station near the coal fields of southern Illinois. This line has the highest capacity of any in this area and includes several novel features, such as a unique carrier current system for tripping the breakers at the remote end of the line, for telemetering, load control, and communication. The 180,000-kva transformer bank at Powerton has two 22,000-volt primary windings connected to different busses. The Crawford transformer bank has a 150,000-kva winding at 220-kv, a 75,000-kva winding at 12-kv, and two 90,000-kva windings at 69-kv for connection to separate 66-kv systems. Regulating transformers are provided at both terminals. A 75,000-kva synchronous condenser at the Crawford terminal is connected to the 12-kv transformer winding for voltage control. No 220-kv breakers are used at either end of the line. This paper describes only the operating features and the terminal facilities; a companion paper by Messrs. Oldacre and Wollaston describes the construction features of the line.