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Show ,1 MINING REVIEW. 5 or induction motors will start under full load, and are capable of speed regulation. The latter possess the good qualities of direct current motors, and the additional advantage of having no commutator and, unless speed regulation is required, neither collecting rings nor brushes; the wires being simply connected to terminals on the field of the machine. On the other hand, the multiphase alternating current, like the single phase retains the indispensable quality, for long distance transmission, of being transformable from low to high voltage for transmission, and from high to low for use at its destination. stalled a light and power plant, the latter conbi polar sisting ef four generators. There are now in use in the mines at Aspen thirty motors, varying in size from 1 H. P., to and 120 II. P., aggregating G22 II. P., which are sued for hoisting, ventilating, diamond drilling and running mills, samplers and miscellaneous machinery. The Virginius plant, Ouray, Colorado. In 1891 the Caroline Mining Company, operating, at great expense for fuel, the Virginius and other mines on Mt. Sneffels, at an altitude of 12,700 feet, took advantage of the new power just coming to the front, and installed an electric plant on Canyon creek, about four miles from the mine. At this distance, wire for 500 volts would be very expensive, so they boldly faced this difficulty by adopting 900 volts, a much higher pressure than had been used before in this kind of work. From this plant they supplied two pumps, a hoist and a blower, and INTER-MOUNTAI- current is taken off from two continuous rings rectifying it, thus avoiding the difficulties experienced with the commutator, of the without machine. By the principle of induction, an alternating current of moderate voltage can be transform. ei into a current of smaller amperage and higher voltage, for transmission, and at the other end of the cau he line to any voltage desired for lights or power, the amperage varying inversely as the voltage. The energy remains the same, excepting a small loss in the transformation, not exceeding 2 per As the coils of the cent, in large transformers. transformer are stationary, and there are no any desired amount of insulation can be used, and almost any voltage can be generated that can be controlled on the line. Many plants are in operation at 10,000 to 12,000 volts, and as high as 50,000 volts has been used experimentally with promising results. The single-phasalternating current is widely direct-curre- nt pro-potii'iial- ly re-transfor- sliding-contact- s, e for lighting, used bat, being a sim- ple alternating is not wave, ble for no N non-snychrono- us : HISTORY. It may be interesting to trace briefly the de- velopment of electric mining operations in. the Rocky Mountain district, and the effects of the foregoing principles and systems on this evolution. First application of electricity in mines. In July, 18S8, the first electric hoist in this region, 100-K- w. 500-vo- lt ran their mills located at the mine After the completion of the Revenue tunnel and mill, the pumps were discontinued s and the were removed to the new mill and others added, and an electric haulage plant is suita- power, as satisfactory altern- single-phas- e ating motor of has yet large size been devised that is mill-motor- und- self-starti-ng er load and ble of speed lation. or built caparegu- If a mot- now being put in the tunnel. This plant is conspicious in the following re- on the lines as a same 9 single-phas- e gene- rator is brought up to speed the proper by some extraneous r, so that powethe al- ternating impuls- spects: High altitude and precipitous nature of country. Severity of lightning. High voltage for act in the right direction at es will V direct the right instants, ind the current is then sent through the Great saving by electricity, a m-ounti- cost of the plant gradually on, it will nm satisfactory at constant speed. a machine is called & o, be ie two, and permit- UPPER END OF POLE LINE, Caroline Mining: Company, Ouray, Colorado. a synchronous mtor, because it runs synchronously or in step with the alternations of the torrent. Its speed cannot be regulated; and if sudden load causes it to slow down and lose Jfep, it stops. It is inconvenient, and in fact practicable, for service where frequent stops tod starts are necessary, because starting it is toch a tedious operation, and if it must start ith load on, it cannot used at all. Multiphase alternating current. The successful development of the multiphase system firing the past four years has solved the prob-fetand secured the advantages of both the Afreet and alternating currents. A multiphase generator has several windings, so placed as to generate several alternating currents differing Phase, that is, passing the zero and maximum hits at different instants. Under the influenc of currents (which may be compared rough-- y l to the cranks of a duplex or triplex engine n dead center), multiphase synchronous totors are self starting under light load, while 111 year or every thrown nch ng the to motor and the load current. ting the profitable working of and probably in the world, was successfully the property at times when it would not otherstarted in the Veteran tunnel, Aspen, Colo. It wise have paid expenses. consists of a 7J H, P. street car motor of one The Anaconda, Montana, tranmission plant. of the earliest types (just coming into use at Several years ago, the Anaconda Copper minthat time), geared to aflat friction-hois- t, used for ing company installed a plant for transmitting hauling cars into the tunnel. Later, it was arranged so that it could be thrown into gear with either this drum or another used for hoisting from an adjacent shaft. This machine has done good work continuously for eight years, and is still in service. Development at Aspen, Colo. To supply this and other similar hoists that soon followed it the Roaring Fork Electric Light & Power Comfrom Hunters creek, pany, using water-powe- r lt installed a generator! same 100 Kw. generator of the and later a type. In 1892, this company developed another waterpower on Maroon and .Castle creeks, and installt led two generators. multipolar This plant was started in the spring of 1893. In 1892, the Peoples Light and Power Company, using waterpower on Castle creek, in- . 45-Iv- 200-K- w. w. bi-pol- ar 500-vo- 500-vo- power 2J miles, to run electrolytic generators in its refinery. Eight lt generators were connected in two series of four each, giving 2,000 volts, and at the receiving-end- , motors were similarly connected and belted to a shaft, from which the electrolytic generators are driven. This arrangement was abandoned some time ago because the total capacity of the waterpower plant was required for light and power in the town of Anaconda ; and a steam-plawas therefore installed at the re100-K- w. eiglit-GOK- w. 500-vo- lt 500-vo- bi-pol- bi-pol- ar ar high-econom- y nt finery. The Telluride plant. In 1891 the San Miguel Consolidated Mining Company, of Telluride, at the juncColorado, developed a water-powe- r tion of the Lake and Howard Forks of the San Miguel river, for the purpose of supplying |