The Kita–Iwaki Powerline is the largest double-circuit powerline for three-phase electric power

Three-phase electric power

Three-phase electric power is a common method of alternating-current electric power generation, transmission, and distribution. It is a type of polyphase system and is the most common method used by grids worldwide to transfer power. It is also used to power large motors and other heavy loads...

 in the world, which was built in 1999. It runs from Minami-Iwaki (Japan) to Higashi-Yamanashi (Japan) and has 2 circuits, which are operated at present with 500 kV

KV

-In physics and chemistry:* Voltage-gated potassium channel,a large family of potassium channels* Kilovolts , 1000 volts* The rating of RPMs per volt as used in reference to the rotational speed of brushless motors...

, but can be switched over to 1100 kV if necessary equipment will be installed. The conductors of the lines consist of 8*31.5 mm ACSR

Aluminium Conductor Steel Reinforced

Aluminum conductor steel reinforced cable is a specific type of high-capacity, high-strength stranded cable typically used in overhead power lines. The outer strands are aluminum, chosen for its excellent conductivity, low weight and low cost...

 ropes providing for a total current capacity of 4000 Ampere

Ampere

The ampere , often shortened to amp, is the SI unit of electric current and is one of the seven SI base units. It is named after André-Marie Ampère , French mathematician and physicist, considered the father of electrodynamics...

s.
The line is supported by pylons

Electricity pylon

A transmission tower is a tall structure, usually a steel lattice tower, used to support an overhead power line. They are used in high-voltage AC and DC systems, and come in a wide variety of shapes and sizes...

 lattice tower

Lattice tower

A lattice tower or truss tower is a freestanding framework tower. They can be used as electricity pylons especially for voltages above 100 kilovolts, as a radio tower or as an observation tower....

s with a typical height of 108 metres. These have three crossbars of spanning 31, 32 and 33 metres.

There are two such lines: the first one is 190 kilometres long and starts at Kashiwazaki-Kariwa Nuclear Power Plant

Kashiwazaki-Kariwa Nuclear Power Plant

The is a large, modern nuclear power plant on a 4.2-square-kilometer site including land in the towns of Kashiwazaki and Kariwa in Niigata Prefecture, Japan on the coast of the Sea of Japan, from where it gets cooling water...

and runs over Nishi-Gunma substation to Higashi-Yamanashi substation. It was built in 1993.
The second 240 kilometres long line, which was built in 1999 starts at Nishi-Gunma substation and runs over Higashi-Gunma substation to Minami-Iwaki substation, whereby it passes close to Shin-Imaichi substation, which is not connected to the line.

Sites

Substation	Coordinates
Higashi-Yamanashi	35°35′26"N 138°47′59"E
Higashi-Gunma	36°34′33"N 139°13′25"E
Kashiwazaki-Kariwa	37°25′33"N 138°35′51"E
Minami-Iwaki	37°22′53"N 140°48′16"E
Nishi-Gunma	36°37′22"N 138°48′6"E
Shin-Imaichi	36°42′46"N 139°49′57"E

External links

• http://www.life-needs-power.de/2008/24-04-2008_Donnerstag/24042008_16-30_LNP_Luxa_1100%20kV-V2%203.pdf