Study of Costs of 69- to 230-Kv Underground Power-Transmission Systems and Tie Lines

This is a study of high-voltage underground-cable systems, consisting of the cable line and the terminal equipment at each of its ends. The study undertaken indicates the economic zone of application of cables and attempts to find an economic relationship between the voltage and the block of power transmitted over distances up to 15 miles. Thirty transmission lines have been designed using both the solid and the oil-filled cables. The lines can be considered as either transmission links with a unidirectional power flow or as tie lines between large metropolitan steam-power stations. The prices of underground cable and terminal equipment were obtained from manufacturers, and refer to the 12-month period immediately preceding World War II. The costs of various system parts, as installed on foundations, were obtained from the study of actual construction projects in different parts of the country and reduced to the 12-month period. The system capital cost and its annual cost are analyzed separately. The quantities of major equipment items in each system are given, and costs of major equipment groups, or of major items, are represented on a percentage basis. Such a representation permits the estimating of the cost of an underground line, or of the entire transmission project, when copper prices and the cost of equipment differ from those taken in the study.