115-Kv submarine cable crossing of the Columbia River

THE FIRST submarine installation of oil filled cables in this country has been made. It is a 115-kv cable crossing the Columbia River just north of the city limits of Portland, Ore. The selection of a nominal transmission voltage of 110 kv was determined by an-economic analysis based on various schemes of delivering energy to load centers in the Portland area. Conditions were found favorable for laying the cable directly on the bed of the river without the digging of a trench. Three cables were laid 4 ft apart, and the shore ends above extreme low water were trenched in and covered with 4 ft of sand. Oil filled cable was found to possess many advantages for this particular service and therefore was specified instead of cable with solid insulation