A modern substation in the Coeur D´Alene mining district

The paper describes a typical mine substation built by the Washington Water Power Company for supplying three-phase power at 2300 volts to the Bunker Hill and Sullivan mine. The substation building is of structural steel which has been adopted in preference to brick on account of the ease with which it may be taken down and reconstructed as the development of the mine may require. The paper gives a detailed account of all the equipment of the substation and includes the total construction cost of the substation, the cost per kv-a. capacity, and the annual operating cost. The connected load of motors at the mine is approximately 3000 horse power. A table of distribution of cost of electric power and light for the average month is given, which shows the cost of this service for different mine operations.