Abstract :
THE placing in service of the 220-kv Powerton-Crawford transmission line of the Commonwealth Edison Company marks the completion of a project begun 12 years ago and subsequently dropped during the depression years. When work was suspended in 1932, most of the right-of-way had been secured, tower sites were located, the tower contracts had been let, typical towers had been built and tested, and some of the terminal apparatus was completed. This line, with a normal rating of 150,000 kva and an emergency rating of approximately 200,000 kva, is to serve as a very important link in the supply to the Chicago area. The plans were carefully reviewed when the project again became active, with the object of incorporating the new ideas that had been developed in the industry for protecting overhead lines from hazards of lightning, sleet, vibration, and galloping conductors. The desired objective was virtually trouble-free operation and this, rather than the lowest cost, was the first consideration. The extent of the advance in the industry is revealed by the present design of the line, which retains only the conductor size of the original designs of 1928 to 1930. Towers, insulators, ground wires, hardware, and all other elements are of present-day design. It is anticipated that the line will have an outstandingly good operating record.
