Koi Koi Grace
by on February 21, 2019
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   Count Alessandro Volta (1745−1827), the Italian physicist and inventor of the battery, was the first person to suggest the idea of a transmission line by writing in 1777 “… the igniting spark could be transported from Como to Milan with barbed wire supported by wooden poles planted here and there …’’ The structures in use those days for telegraph poles were wooden poles with zinc iron barbed wire supported by porcelain insulators fixed to the pole with screws and bolt hooks (TERNA, 2013). The first industrial transmission line ran somewhere between Tivoli and Rome in 1882. The line carried a 5.1 kV single-phase circuit supported by metal fixtures made of double beams, concrete bases and insulators mounted on bolt hooks with wires made of copper. On September 16, 1882, Miesbach in Germany became the starting point for the first long distance transmission of electric power in the world. A 2.4-kilovolt direct current (DC) power transmission line transferred electricity from Miesbach over a distance of 31 miles (50 km) to Munich.

However, the first long distance transmission of electrical energy occurred in 1884 during the Turin Expo. A 3 kV single phase current was sent over a 26-mile (42 km) line from Como to Lanzo, Italy. The supports were wooden poles and bell insulators with bronze wires were used. The construction of the first three-phase 12 kV alternating current (AC) overhead transmission line took place in 1891 between Lauffen and Frankfurt, about 112 miles (180 km), coinciding with the International Electricity Exhibition in Frankfurt. Back in Italy, the Tivoli-Rome line was followed in 1898 with a 20-mile (32 km) line between Paderno and Milan: the first 3-phase circuit with metal pylons and delta-type multiple bell insulators with copper wires. In the United States, the first power transmission line operated at 4 kV. It went into operation in June 1889 between Willamette Falls and downtown Portland in Oregon, running about 13 miles (21 km).

In 1912, the first 110 kV overhead transmission line was constructed between Croton and Grand Rapids, Michigan. The year 1913 saw the construction of the biggest and longest high-voltage line – the 150 kV Big Creek Line in California – which spanned 250 miles (402 km). The following years witnessed technical advances and rapid developments everywhere. The first 220 kV lines were constructed in Germany and Italy in 1928; by 1936, a 287 kV line was built between Hoover Dam in Nevada and Los Angeles, California. Sweden built the world’s first 380 kV line from Harsprannget to Stockholm, running 596 miles (959 km), in 1953. At the same time, American Electric Power (AEP) constructed the first 345 kV transmission line. In most cases, the average design spans between structures ranged from 1000 to 1500 ft (305 to 457 m); almost all lines used aluminum-steel conductors, bell insulators and latticed steel towers. Hydro-Quebec in 1965 built Canada’s first 735 kV overhead line; soon, Russia and USA built overhead lines at 765 kV – then the largest voltage in the world. A 1200 kV line was commissioned in the Soviet Union (now Russia) in 1982.

 

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