Direct-current generator is a machine that converts mechnical energy into direct-current electrical energy. It mainly works as direct current electrical source of direct current motors, electrolysis, electroplating, electric smelting, charging, excitation of alternating current generator and etc. Though it also uses electrical power current adjustment elements where direct current is needed to convert alternating current into direct current, alternating current adjustment can't work as well as direct current generators on the ease of use, reliability of operation, and some functions. The rated voltage that medium and small direct current generators output is not high; it can be 115 volts, 230 volts, and 460 volts. The one that large direct current generators output is about 800 volts. Direct current generators that output higher voltage belong to high-volt special machine group, and are less used.