Development of High Temperature conductors for Power Transmission Lines

Abstract

Aluminium with low strength and lower conductivity than Copper is currently used in the electric transmission lines. An Al conductor can normally transmit 78% of the load that can be carried by a Cu conductor of equivalent cross-sectional area for the same rise of temperature. For equivalent resistance per unit length, an Al conductor requires 28% greater diameter than Cu but weighs only 1/2 as much. Presently, Al conductor is being used with steel reinforced at the core (ACSR). However, recent requirement from the point of energy loss, it is being planned to have an all alloy aluminium conductor (AAAC)with electri-cal conductivity higher than the present ACSR by 10% (58-60% IACS) and UTS of -250MPa. The alloy chemistry has been modified considering the present alloy AA6082 which cons-ist of Mg and Si as alloying elements. The total alloying content was kept within -2 wt.%. By varying Mg:Si ratio along with addition of Misch Metal (MM) it is observed that a slight addition of MM led to 56% IACS along with 225 MPa UTS. This alloy was initially cast in thick metallic molds and later it has been changed to circular mold as the input material for wire drawing has to be in the circular form. However, the surface roughness of the wire was not proper. It is proposed that for better wire drawing it is required to study the solididication process in the properzi casting method.