50,000 volt three-phase transmission from the Missouri River

50,000 Volt Three-phase Transmission from the Missouri River.—The Electrical World of New York for July 13th publishes an illustrated article on the Missouri River Power Co.'s 50,000 volt transmission plant from Cannon Perry to Butte, Mont. At Cannon Ferry the river valley is of such a shape that by building a dam 500 ft. long and about 40 ft. high a lake 1/2 mile wide and 6 miles long was formed. The available head is 32 ft. Four units of 1,200 H.P. consisting of Westinghouse 60 cycle generators directly coupled to Dayton Globe Iron Works turbines have been installed, and at present supply Helena, Mont., over a 12,000 volt line, and six more units are being fixed. The distance to Butte is 70 miles. Two polo lines, 50 ft. to 100 ft. apart, will each carry one circuit, the wires being placed in a triangle 66 in. apart. The pins will hold the insulators 9 in. above the cross-arms, and are secured by 3/8 in. bolts. The pins driven into the pole tips will have 3.8 in. vents to drain water from the pin hole. At Butte there will be a sub-station containing six 980 kw. oil transformers, water-cooled and connected delta fashion. The motors will be supplied at 2,000 volts, except in the case of very small machines. Ordinarily the whole system will be operated in parallel, but double bus bars will enable the lines to be operated independently.