Comparison of the economics of paper-oil and polymer-fluid extra-high-voltage cables

Pressures have been growing for increased power transmission via underground cables, in spite of costs which may be 10 to 20 times as great as for corresponding overhead systems. To reduce these costs, the trend has been toward higher power capability through higher operating voltages. This has led to a growing concern over increasing dielectric losses and to a more careful consideration of the replacement of the widely used paper-oil insulation by other lower-dielectric-loss systems (e.g., polymer and pressurized gas). In this paper we examine the limitations on the oil-paper system for voltages above the presently used maximum of 345 kV and compare costs with a model fluid-impregnated polymer system.