BUNDLED CONDUCTORS IN TRANSMISSION LINE

BUNDLED CONDUCTORS IN TRANSMISSION LINE
Bundling of conductors in a transmission line is a product of experts' ingenuity.

In support to this post regarding bundled conductors, we will discuss here how bundling of conductors can affect the losses in the transmission lines.

Bundling of conductors in the transmission lines helps lessen the effect of the two major phenomena the exist especially in voltage levels of 220kV and up namely; the CORONA effect and the SKIN effect.

Corona, also known as partial discharge, is a type of localized emission resulting from transient gaseous ionization in an insulation system when the voltage stress, i.e., voltage gradient, exceeds a critical value.

Conductor bundling supports the system in minimizing losses due to corona effect and audible noise. Bundle conductors is made up of several ACSR conductor cables connected by non-conducting spacers. In a 220 kV transmission lines, two-conductor bundles are usually used, while in a 380 kV lines usually three or even four. American Electric Power is building 765 kV lines using six conductors per phase in a bundle. Spacers must resist the forces due to wind, and magnetic forces during a short-circuit. (wikipedia)

4 wire spacer

Bundle conductors are used to increase the amount of current that may be carried in a line. Due to the skin effect, ampacity of conductors is not proportional to cross section, for the larger sizes. Therefore, bundle conductors may carry more current for a given weight.(wikipedia)

A bundle conductor results in lower reactance, compared to a single conductor. It reduces corona discharge loss at extra high voltage (EHV) and interference with communication systems. It also reduces voltage gradient in that range of voltage.(wikipedia)

One known disadvantage for a bundled conductor, the bundle conductors possesses higher wind loading.

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