Developments in insulation for high voltage overhead transmission systems

By facilitating the transmission and distribution of electrical energy at relatively low cost, overhead lines have played a very important role in the growth of our modern technological civilization and will continue to do so to an increasing extent in the future. For major electrification schemes the investment in overhead lines is between 20 and 40% of the total expenditure. Insulation accounts for about 10% of line cost at 132 kV, rising to approximately 25% at 750 kV.