Electric Power Generation

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World Power Grid

Worldwide Grid of 50hz and 60hz Power

Why is it that some regions of the world use 60 hz power and other regions use 50hz power ?

All of North America and the Northern portion of South America operate 60hz grids.

With a handful of exceptions, the rest of the world is 50hz. 
Japan is unique in that about 50% of the country uses 50hz power and the
rest of Japan uses 60 hz power.

Here’s how it all happened:

60hz standard for North America

In 1878, Thomas Edison formed the Edison Electric Light Company.  In 1882, Edison’s Pearl Street power station in downtown New York City began supplying DC power to 52 customers within a 1 square mile region.  A bright Serbian engineer by the name of Nikola Tesla, emigrated to the US in 1884 to go to work for Thomas Edison.  Tesla had his own theories on electricity and soon had a falling out with Edison.  In 1885, Tesla sold his patents on AC power generation to George Westinghouse and together they went into competition with Edison.

Edison was promoting low voltage DC power for safety purposes but unfortunately, this would have required generating stations every few blocks and was not economically practical.  With AC power, electricity could be produced at higher voltages and transmitted economically over great distances.  Westinghouse and Tesla experimented with different frequencies for AC power and concluded that the lower the frequency, the lower the losses over transmission lines. A 20hz design looked promising but 20hz power caused an annoying flickering in lighting.  A frequency of at least 50hz was needed to eliminate the flickering.  Westinghouse had originally favored 133.3 hz because the steam turbine driving his first generator was optimized for 2000 rpm and his generator had 8 poles.  The resultant 8000 cycles per minute or 133.3 hz was good for lighting but less efficient for power transmission.  They settled on 60hz since the induction motor, another invention of Tesla, was optimized for 60hz.

50hz standard for Europe

The first demonstrated transmission of electricity over a long distance occurred in 1891, first in the US and a few months later in Germany.   Allgemeine Elektricitaets-Gesellschaft (no wonder they shortened this to AEG) built its first generator with a 50 hz design.  As power grids were created in Europe, the 50hz standard stayed in place because that was the design of the alternator being manufactured by AEG.  Most of the colonies and territories of Western Europe were outfitted with electrical systems from their motherlands while the US influence covered most of South America.

Japan has 50hz and 60hz

The development of the Japanese power industry started with the formation of Tokyo Electric Lamp Company in 1883. In the following several years, the same kind of companies were also founded in Kobe, Kyoto, Osaka and other cities. The early systems of transmission and distribution in Japan, like in America, used Edison's DC system, but as demand for electric power increased, high voltage alternators were adapted. Tokyo Electric Lamp Company bought alternators made by AEG in Germany while at the same time, Osaka company in Western Japan bought an alternator made by General Electric Company. The GE alternator was manufactured under a license from Westinghouse, the same license that Tesla had sold to the Westinghouse Company.

Today, the Japanese grid has two discrete regions that are not interconnected.  Western Japan is 60Hz and Eastern Japan is 50Hz. The dividing line is the Oi river in Shizuoka prefecture about half way between Tokyo and Nagoya. In some ways, this is comparable to the unconnected grid regions in the US.  While all of the US is 60 hz, the regional grids are not synchronized with one another and therefore not interconnected except for small amounts of power flow over special DC ties.