DC POWER SUPPLY SYSTEM AND SWITCH

A DC power system comprises a rectifier which converts AC power supplied from an AC power source in a station into DC power to supply the DC power to a DC load, and a storage device normally charged by the DC power output from the rectifier. The storage device is divided into a DC short-time storage device 27 to maintain power supply only for a predetermined short time when power supply from the power source in the station is cut off, and a DC long-time storage device 37 to maintain power supply for a time relatively longer than that of the DC short-time storage device. The DC short-time storage device 27 comprises an electric double-layer capacitor having a predetermined high output density, and the DC long-time storage device comprises a second battery having a predetermined high storage power density.