The vincent 220-kv. transmission line: Engineering and construction features

This paper deals with the design and construction of the third 220,000-volt line between Los Angeles and Big Creek, giving the results and brief descriptions of the research engineering investigations which were carried out in connection with the design. The salient features of the line are: Terminals — Big Creek No. 3 and Gould Switching Station, near Los Angeles. Length — 223.5 mi. Route — Direct route with few angles. Dead-ends — Dead-ends only at station terminals and heavy angles. Small angles — Small angles up to 11 deg. 40 min., in some cases, turned on suspension insulators. Conductors — Steel reinforced aluminum. 1,033,500 cir. mils aluminum, 54 strands. 134,000 cir. mils steel, 7 strands. Weight: 1.33 lb. per ft. Diameter: 1.247 in. Overhead Ground Wire — None. Towers — Towers of high elastic limit steel. Height of standard towers, 64 ft. to crossarm. Height of anchor tower, 56 ft. to cross-arm. Weight of standard tower, 8890 lb. Weight of anchor tower, 13,600 lb. Tower Footings — Grillage footings in earth. For standard towers, 4 ft. 8 in. sq. at base and 8 ft. deep. Weight, 2040 lb. For anchor towers, 7 ft. 6 in. sq. at base and 9 ft. deep. Weight, 6720 lb. Tower Extensions — Height 7, 14, or 21 ft. Any of these heights may be placed on any or all corners of the tower and in a few special cases in combination with an additional 14-ft. extension on all corners. Insulators — 10-in. cap and pin having minimum combined electrical and mechanical strength of not less than 18,000 lb. Suspension insulator assembly: Single string of 13 units where maximum stress in string will not exceed 6000 lb. Double string 13 units in length where maximum load will exceed 6000 lb. Dead-end assembly: Double string, 15 units in length. Tie-down assembly: Single string of 14 units. Shield Rings — Hoops of 8-in. by 3/16-in. strap iron. Bird Guards — Pans and saw-tooth guards on all towers. Increases in the generator capacity at Big Creek, which are scheduled to be completed in 1928, will require more transmission capacity to deliver the power to Los Angeles. For this reason, a third 220,000-volt line is being built between those points.