An important advantage for AC became apparent with the invention of the transformer in 1883. This meant that the voltage from an AC generator could be efficiently increased for transmission and then decreased at the other end for use in the home or factory. From our previous explanation, electrical energy is proportional to voltage times current, so that boosting the voltage means that the same amount of energy can be transmitted with less current flow. Since heat produced in the line is a function of the current and the resistance, less current means fewer losses due to heat. For short distances of a mile or so, this made little difference. But for long distances, it would be critical.
The Westinghouse and Thomson-Houston companies preferred AC, and their faith was justified when Nikola Tesla invented a practical AC motor in 1888. Additional Tesla polyphase patents made AC systems more efficient, and these patents were used by Westinghouse at Niagara Falls in 1895. During the 1880s a sometimes fierce (and not always logical) battle was waged between proponents of AC and of DC. Edison himself became less involved as he devoted more time to his new laboratory at West Orange, New Jersey, after 1886, and as he became more involved with his iron-ore project. The Edison and Thomson-Houston companies merged in 1892 to form General Electric.
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