115-Kv submarine cable for Columbia river crossing

Outstanding among cable installations is the recently completed 115-kv oil filled submarine cable which crosses the Columbia River between the states of Washington and Oregon. Three single-conductor hollow-core 750,000-cir-mil cables having armor wires of hard drawn copper instead of steel, are laid directly on the bed of the river 4 ft apart, and cross 2 channels of the river, 3,460 and 1,360 ft in width. These crossings are connected by an overhead transmission line. A 33-ft maximum difference in the water level of the river necessitated the solution of a number of problems at this installation. The many interesting features are described in this article, which is divided into 4 main sections. The first section describes the general reasons for the principal decisions regarding the cable, the second describes the specifications and manufacture, the third describes the design of the field installation, and the fourth covers installation and construction methods. Each section contributes valuable information in its respective field.