Economics of high-voltage transmission by underground cables

The general trend of cable design and costs are reviewed and consideration is given to capital charges, I2R loss, sheath loss, dielectric loss and reactive compensation. It is shown that for the higher voltages the costs of the dielectric loss and reactive compensation are more important than those of the I2R loss. These fixed costs and also the charging current and impulse strength are dependent on the value of the designed maximum stress on the dielectric, and it is shown that the value of this stress must not be increased without consideration of all its etfects. The total cost of cable installations is reviewed and the economic voltages for various loads derived. The total costs of cable installations are analysed and examples given of the increase in cost of energy due to transmission. The author appreciates that the choice of voltage and cable size is not governed solely by considerations of the cable, since the cost of terminal equipment, short-circuit duty and voltage drop are sometimes the determining factors, These considerations are, however, outside the scope of this paper.