Engineering Features of the 230-Kv Boulder-Chino Transmission Line of the Southern California Edison Co., Ltd.

Abstract

The economic restrictions of base-load operation plus the necessity for a high degree of reliable service owing to the relatively large amount of power to be transmitted, has led to the design of a single- circuit transmission line with two overhead ground wires, counterpoises, and ground-fault neutralizers with an expected service continuity record closely approaching that which heretofore was Obtainable only by two transmission lines located on separate rights-of-way with crossovers and paralleling switching stations. With this new design, flashovers caused by lightning are expected to be reduced to single line-to-ground faults by the two overhead ground wires and counterpoises and suppressed by the ground-fault neutralizers. Permanent ground faults are not to be removed immediately, but are to be allowed to remain on the line until the load can be backed off the Boulder Dam generators. This alleviates the shock to the system which might otherwise occur if the load was rejected immediately. Operating in this manner is possible with ground-fault neutralizers in the power-transformer neutrals. The installed cost of the ground-fault neutralizers which permits the single- circuit line to approach the double-circuit line in performance, is less than five per cent of the cost of the second line. The successful suppression of the line-to-ground arcing faults demonstrated conclusively that ground-fault neutralizers will function on 230-kv circuits with inphase Phase components of current of the order of 80 amperes.