ABSTRACT
The coastal region of Lima, Peru, is an aggressive salt-laden atmosphere classified by ISO 9223 as an S1P1 mixed atmosphere, having high deposition rates of Cl– ions and SO2. Lima has little rain, so the ions are not easily washed away, but instead concentrate with daily fogs. Overhead power transmission conductors in this region are required to be both of all-aluminum constructions (no steel), and to have grease between layers, in order to give longer environmental durability. This paper reports on an ongoing environmental field trial of a high-temperature low-sag ACCR (aluminum conductor composite reinforced) conductor. The conductor contains aluminum and aluminum matrix composite constituents, and for the first time uses a greased configuration. Samples were periodically harvested from the field, and characterized using microscopy and strength testing. A comparison in behavior is drawn between greased and ungreased conductors that shows the beneficial role of the grease between the layers, for protecting the aluminum strands.
INTRODUCTION
Some salt-laden coastal regions of the world experience high corrosion rates of aluminum due to the presence of high levels of Cl– ions and SO2. For overhead power conductors this presents a life limiting problem, due to the effects of atmospheric attack on the aluminum strands. One traditional solution to this is to manufacture the conductor filled with a grease in order to exclude the environment. In the last 10-20 years, new high temperature low sag conductors have entered the power industry, but as yet have not been used in a greased configuration. Newer high temperature greases have been developed to meet the demands of the higher operating temperatures of these conductors. For the first time, an ACCR conductor has been manufactured using a high temperature grease to meet the combined demand for a high temperature low sag conductor in a highly corrosive environment. Also, for the first time, this conductor has been placed in a highly corrosive field environment to monitor how it performs. This paper reports on the progress of the field study.
