Distribution

Of the various systems of electrical distribution, each may be classed under one of two headings; namely, direct and alternating current. These two systems may be still further subdivided into parallel and series systems of distribution. The direct-current parallel system, commonly known as the Edison three-wire system, is one of the oldest systems for the practical distribution of electrical energy. The general principal of this system involves the connection of two generators in series, having a tap carried out from the connection between them, thus providing three wires for the transmission of the current. The capacity of the system may be increased by simply adding an even number of dynamos of similar voltage as the first pair, and connecting them in the same manner as described, or by the addition of batteries or single generators that generate current at double the voltage of the single generator operating in series. This system is used principally for furnishing light and power in the congested or built-up sections of a city.