Engineering features of the 230-kv Boulder-Chino transmission line of the Southern California Edison Co., Ltd.

THIS paper deals with the problem of transmitting Boulder Dam power to the Southern California Edison Company´s system. Preliminary studies were made of this project on the assumption that it should be a high-capacity peak plant with a high degree of reliability of service.¹ It was soon recognized, however, that this power was to be delivered to a system already well equipped for peak demands. This led to a reconsideration of the problem of disposing of this power and the fitting of it into the existing system of the Southern California Edison Company as a base-load-supply project. To justify this base-load operation, it was necessary to keep as low as possible the annual cost of a kilowatt-hour delivered from Boulder Dam to the company´s system. However, since this power, 165,000 kw, was about 25 per cent of the present peak load on the system, service reliability of the transmitting facilities was still a major factor. In addition, it was desired to include those features of the peak-plant design which could not be added economically at a later date should the project be converted to a peak-load plant. High inertia constants and low reactance were retained in the design of terminal equipment for such an eventuality.