Publication: Street Railway Journal
New York, NY, United States
Long Distance Transmission of Electric Power.
By T. A. W. SHOCK.
The Sacramento Electric Power & Light Company was the pioneer of the world to transmit power in large units over a long distance. Thirty years ago the idea of building a dam across the American River for irrigating and power purposes was thought of by H. G. Livermore, the father of H. P. Livermore, the present general manager. The work has been continued under Albert Gallatin and H. P. Livermore, and to-day at Folsom may be seen one of the most extensive hydraulic works in the world. The dam contains 37,000 cu. yds. of masonry. It is fitted with a shutter operated by five hydraulic rams, and when shutter is raised reservoir back of the dam is formed holding 13,000,000 cu. yds., of water; thrust of dam, 1911 tons; stability, 7979 tons. A canal 50 ft. X 40 ft. X 8 ft. conducts the water from the dam to the power house, distance 1 3/4 miles.
The power house is a substantial brick structure, built on granite foundations, and contains four 1200 h. p., horizontal McCormick turbines, coupled direct each to a G. E. 750 k. w., three phase generator. The generators are excited by 30 k. w., 500 volt multipolar generators which are direct coupled to their individual wheels. The Faisch & Piccard water governor is used, and on a test regulated within four per cent from no load to full load. The generators at full speed of 300 revolutions run at a pressure of 800 volts, which is raised to 11,000 volts through step-up transformers. There are nine step-up transformers in the station, of 560 k. w. capacity each.
The power is transmitted to Sacramento over two pole lines. The poles are forty foot, round Washington cedar set six feet in the ground, and a large standard General Electric porcelain insulator is used, which has a factory test of 30,000 volts before shipping. Each pole line has six wires, and each set of three wires has a capacity of 1000 h. p. The necessity of a double line has often been demonstrated, as the service during the twenty-four hours cannot be interrupted. By means of switches at Folsom and Sacramento the power can be thrown to any line or any set of transformers, so that in any event an interruption to the service can only be a matter of a few seconds. The line has stood the severe gales of the past winter, only a few minor repairs having to be made.
At the substation in Sacramento the current is transformed down through step-down transformers of 125 k. w. and 40 k. w. capacity to 1000, 500, 230 and 115 volts for power and incandescent lighting.
In this station are three 325 h. p. synchronizing motors, which are coupled by means of friction clutches to a countershaft, to which are belted one M. P. 200, an M. P. 90 and two Edison 80 k. 500 volt generators for operating twenty miles of street railway owned by the company and four small 500 volt motors. To this countershaft are also belted three 100 light Brush arc machines and two 125 light machines of the same type for city and commercial lighting. The company has in operation 234 city lights, 117 commercial arcs and 3000 incandescent lights, 150 h. p. in small direct current motors and 100 h. p. in small three phase induction motors, also operating twenty-two regular cars on its street car system. Electrical machinery is now being placed in the Buffalo brewery, Phoenix mills and other institutions, and recently a contract was closed with the Southern Pacific Company for electric power for its shops. The plant both at Folsom and Sacramento is duplicated throughout, thus avoiding any possibility of a shutdown.
The low tension distribution is laid out on the standard four wire "Y" system, the three wires of the three phase and neutral system for incandescent lighting and small motor work. Motors can be operated successfully on this system without any apparent change of voltage to the lamps. In addition to the low tension distribution for incandescent lighting a 1000 volt line is run, stepping down to too volts at the transformer for residence lighting and outside motor work.
The plant commenced operation July 16, 1895, and has been operating constantly ever since. This proposition is the pioneer for similar propositions in this state, which are now being installed, and prove to the world that it is a success electrically and financially. To commemorate the coming in of electric power an electric carnival was given on the night of Sept. 9, 1895, which in splendor could not be beaten the world over. Ten thousand incandescent lights, in the form of circles, towers, Maypole and signs, were burning on that night, and those who saw it will have the satisfaction of knowing that they were able to see one of the grandest exhibitions of the nineteenth century.
Another achievement in the electrical field, and which is coincident to the entrance of electrical power, is the successful operation of a long distance telephone over a pole line carrying 10,000 volts.
A test of the power plant showed ninety-seven per cent efficiency of transformers, ninety per cent in the line, and the water wheels eighty per cent. All the machinery has come up to guarantees and in the case of transformers and generators have exceeded the guarantees one and two per cent.
* Read at the first annual meeting of the California Street Railway Association, April 21, 1896.