Round wires versus trapezoidal wires in ACSR and ACSS overhead power transmission conductors.
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Date
2015
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Abstract
In overhead power transmission, the greatest need is to transmit maximum power with reduced
losses, minor environmental impact and minimal infrastructure degradation, at low costs. The
conductor material and shape (form) are deemed to be amongst the main determinants for
optimal power transfer. Various forms such as trapezoidal (TW), aero-z (Z) and round-wires
(RW) have been developed for bare overhead power transmission conductors. About 80 % of
power utilities around the globe, including South Africa, use Aluminium Conductor Steel
reinforced (ACSR) conductors formed in RW for power transmission lines at voltages above
132 kV. Interest is also shown by some power utilities to use High Temperature Low Sag
(HTLS) conductors, mostly Aluminium Conductor Steel Supported (ACSS) for short
transmission lines. In this study electrical performances of ACSR and ACSS conductors in TW
and RW forms were evaluated. The electrical characteristics considered are thermal ratings,
power losses and magnetic fields. Particular reference was made to Eskom’s 400 kV power line,
using the Power Line Systems - Computer Aided Design and Drafting (PLS-CADD) software
program for the magnetic fields analysis. RateKit 5.0 software which uses both IEEE 738-2002
(IEEE) and CIGRÉ methods was used for conductor thermal rating calculations. The power
losses were calculated using the resistances and the maximum allowable current on the
conductor. The results showed slight differences between RW and TW in terms of the electrical
performances. Most of the differences are due to the variances in resistances and diameters of
the conductors resulting from the shape of the conductor.
Description
Master of Science in Electrical Engineering.
Keywords
Power transmission., Electric lines -- Superconducting., Overhead electric lines., Theses -- Electrical engineering., Aluminium Conductor Steel Reinforced (ACSR)