ECONOMIC INCENTIVES FOR LARGER TRANSMISSION CONDUCTORS.

There are several recent examples of 500 kv lines using four 1. 3 inch conductors (4800 kcmil), where in the late 1960's, two 1. 6 inch conductors (3500 kcmil) would have been used for a similar application. Economic pressures are an important factor in this change. The lower future losses on the four conductor line more than offset the greater initial cost. This paper describes line costing trends that are leading to the use of increasing conductor sizes. Also, while the economics are applicable to conventional line configurations, EHV line configurations are considered which have recently been proposed and are departures from present industry practice. These new line configurations in particular will benefit from the use of larger conductors to offer improved environmental performance, and their dimensions identify an area of line design, namely phase-phase switching surge flashover of conductor-conductor gaps, that requires further research.