history of currents

A Short History: War of The Currents

AC became the preferred method of power transmission throughout the world, but DC technology was never entirely forgotten

It’s hard to grasp the fact that electricity originated as direct current (DC) and the first distribution system was DC, as was the first long-distance transmission system. In 1882 Rene Thury, one of the pioneers of DC, developed a DC line between Miesbach and Munich. It was only 2-kV and ran about 35 miles (57km). By the early 1880s, Edison had perfected the incandescent lamp or light bulb as it is more popularly known, but an electric distribution system was needed. Fortunately, the first commercial dynamo (DC generator) became available about the same time Edison’s light bulb started getting popular. As a result, Edison invented or improved a lot of devices needed for that early DC electric system, earning him many patents on DC equipment. Within a short time, there were over 200 electric companies in North America using DC systems and all paying patent royalties to Edison.

With the growth of his electrical empire, Edison hired a young engineer from Europe, Nikola Tesla to improve the equipment used in the DC distribution systems. Tesla improved the dynamo, but he also presented Edison with innovative ideas based on the new alternating current (AC) technology. Needless to say, Edison was less than enthusiastic about AC or Tesla. He was too vested in DC technology. The two geniuses parted company. Once Tesla was on his own, he designed a complete AC system. He was awarded seven U.S. patents for polyphase AC motors and power transmission equipment. About that time George Westinghouse entered the battle. He believed in the new AC technology and struck up a deal with Tesla to purchase Tesla’s patents. The war of the currents, as historians call it, was underway big time. It was an epic battle between these two geniuses and the technologies of AC and DC.

There was a great deal of turmoil until the Westinghouse/Tesla AC system was selected to illuminate the 1893 Chicago World Fair. Tesla’s polyphase system of AC power generation and transmission system was about half the price of the DC system and required far less infrastructure. From that point onward, most of the electrical devices ordered in the U.S. were for AC voltages. AC became the preferred method of power transmission throughout the world, but DC technology was never entirely forgotten. From the start, engineers recognized that AC and DC were complementary technologies rather than competing technologies, which is shown in today’s HVDC overgrid and mesh network schemes being explored currently.

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