Electricity - The Power Transmission System of Gold King Mill in Telluride

An interesting example of electric-power transmission is that of the Gold King stamp-mill near Telluride, Col. A Pelton wheel, receiving water through a two-foot steel pipe under 320 feet head, drives the generator at a speed of 833 revolutions, giving 10,000 alternations per minute. The generator, by an automatic compensation, is made to maintain a constant pressure of 3000 volts at the motor, three miles distant. The line runs 2500 feet directly up the mountain from the power station, and thence passes over a rough, and in winter almost inaccessible, country, to the mill. The working motor, being of the synchronous type, requires a special device for starting it, and this is furnished by a small auxiliary motor of the Tesla type. The operation of starting is accomplished by one man in about two minutes. The economical efficiency of the synchronous motor system, exclusive of loss in conductors, is found to be 83.5 per cent. at full load and 74 per cent. at half load. The capacity of the motor is 50 horse-power. This is the first example in this country of the installation of a large alternating motor, but the results already attained indicate that the simplicity, flexibility and wide range of application of the alternating system, are likely to make it, at least for large enterprises, the system of the future.

An alternating current power-plant is now under construction for a quartz-mill in Colorado which will have a generator of 750 horse-power and a motor of 250 horse-power located at a distance of ten miles. By making use of a pressure of 4000 volts at the generator, and allowing a loss in the line of 20 per cent., the cost of copper in a line of this length becomes only from 10 to 15 per cent. of the aggregate cost of the plant.