Analysis of AC resistance in non-ferrous bimetallic solid conductors

This paper provides an analysis of the AC resistances obtained for non-ferrous bimetallic solid conductors. Specifically, the two most common power conductor metals are used: aluminum and copper. The effects on AC resistance for designs of aluminum conductors with copper cores and copper conductors with aluminum cores are examined. The mathematics influencing the increased AC vs DC resistance are provided along with current industry practices used to mitigate the increase of the AC/DC resistance ratio. On large power conductors, normal practice to reduce the AC/DC resistance ratio is to divide the conductor into multiple segments. In this paper the effectiveness of this segmented technique is discussed, followed by an analysis of the novel idea of using bimetallic conductors.

I. Introduction

Currently, typical conductors for AC power transmission and distribution have relied on a single metal to carry the bulk of the current/power. Generally, the primary conducting metal is either aluminum (AL) or copper (CU). Some special bimetallic designs are used in the industry, however the intention is only to use one metal as the current carrying material and the other for desirable application-driven properties, such as the mechanical strength of the steel used in ACSR conductors. Aluminum and copper both have unique advantages and disadvantages, including load capacity, cost, weight, size and susceptibility to corrosion. By using a combination of these two conducting materials, optimal hybrid bimetallic conductor designs of both aluminum and copper are possible.