Publication: Electrical Age
New York, NY, United States
Kern River No. 1 Power Plant
The continuation of the description of Kern River No. 1 Power Plant of the Edison Electric Company, of Los Angeles, is given in the Electrical World, August 31, 1907. The article starts in with a description of the transmission towers. The data given for calculating strains on the towers is taken on a basis of a wind pressure of 30 pounds per square foot on the tower and the wire of a 700-foot span. The towers will also withstand absolute failure of any single wire, even though none of the resulting strain is transmitted to adjacent wires. There are nine insulators, spaced on six-foot centers, five on the upper of two cross-arms, and four on the lower, the arms consisting of 9-inch 13 1/4-pound channels. A standard 60-foot tower is 12 feet square at the base, the uprights are formed of 4-inch angles and the cross braces of 2-3/4-inch, 3-inch and 3-1/2-inch angles, the diagonal rods being 11/16-inch and 5/8-inch in diameter. Four insulators for the telephone lines are mounted on one cross bar twenty-one feet above the ground. Forty of the towers were made extra heavy for use at points where the line changed its direction.
The insulator pins are of cast-steel, and were furnished as a part of the tower. They are secured to the tower by four bolts and are cemented into the insulators.
The transmission line is" designed to consist of three circuits with wiring spaced symmetrically on six-foot centers. This wire is 7 strand 4-0 hard drawn copper, having an elastic limit exceeding 35,000 pounds total, and an ultimate strength of 62,400 pounds.
The insulators are stated to be the largest yet made for commercial transmission purposes. They are 18 inches high, and 8 inches in diameter at the grooved top. The top section i; 18 inches in diameter, and the two lower petticoats are respectively 14 inches and n inches in diameter. Each assembled insulator weighs 50 pounds. They are light gray in color to harmonize with the color of the towers. Specifications called for a guarantee of a 100,000 volt test from the groove to the pin for half an hour under a precipitation of one inch in five minutes at an angle of 30 degrees from the vertical. The assembled insulator was required to withstand a wet test of 150,000 volts for 30 seconds, and the separate parts are guaranteed to withstand a voltage of 25 per cent, in excess of the normal proportion of over-voltage test. The insulators are guaranteed to withstand a side strain of 4000 pounds, and actually fail at approximately 9000 pounds.
The article then goes on to describe the switching stations and substations, touching on the hydraulic features.