Mine Substations

The use of electricity in mines has been making rapid progress throughout the United States. Steam and compressed air are being superseded largely by central station power. Power from a central station requires a substation to supply direct current to operate locomotives, cutting machines, etc. A substation is used to transform high-voltage a-c. power to direct current at 250 or 500 volts. Substations, when possible, should be located on the surface, because if located underground there is danger from fire, and dampness weakens insulation and causes corrosion of metallic parts. Construction of an underground substation is more costly than on the surface, as there is danger of the roof giving way. The roof should be arched, or built of heavy concrete and the whole station made fireproof. When substations are located underground it is necessary to carry a high-tension cable through bore-holes. When located on the surface a low-tension cable can be used. Many accidents occur because of incompetent men. Good salaries should be paid and competent men obtained. Danger warnings should be posted and men taught to consider wires as being ``live´´, thereby lessening accidents.