AN EXPERIMENTAL STUDY ON THE INFLUENCE OF TEMPERATURE ON THE FATIGUE BEHAVIOR OF POWER CONDUCTOR CABLES MANUFACTURED WITH AL 1350 ALLOY
Orchid; fatigue; high voltage.
This thesis has exploratory objectives of an experimental nature, whose main objective is to present an analysis on how the influence of temperature affects the fatigue life of the Orchid conduit. In this sense, to reach the general objective it was necessary to implement an engineering solution based on a PID control that provides real temperature conditions, whose high voltage cables are subjected daily during their useful life. Thus, the development of controlled infrared heating equipment for the connection between the conductor cable and the suspension clamp (regions susceptible to fatigue failure) will be presented. In this sense, a device responsible for heating and temperature control in the connection region was implemented and tested. The series of tests was carried out to evaluate the operation, the experimental device demonstrated excellent performance and satisfactory operation, and the operational criteria were fulfilled, to carry out the fatigue test on the cables under high temperature conditions. Continuing the investigation, two test steps were performed under fatigue conditions, nine tests at 75°𝐶 (maximum conductor temperature for ampacity calculation) for step one (E1), whose results were compared with literature data at room temperature. And seven trials for step two (E2), with four trials at 21°𝐶 and three trials at 75°𝐶. The analysis of E1 allowed to verify a reduction of the order of 30% in the useful life in the samples tested at 75°𝐶, considering as failure criterion the rupture of 10% of the total number of aluminum wires. Assuming the first breakage of the aluminum wire as a failure criterion, the average reduction in the useful life of the conductor was only 10%, the E2 analyzes corroborated this result and presented an average reduction between the tested amplitudes of 9% reduction. This comparison allows us to affirm that the survey of the comparative experimental curves for the cable/clamp assembly constitutes an interesting and strategic tool for the design of transmission lines, as well as establishing parameters capable of leading to projects of retraining, preventive and corrective maintenance of existing transmission lines. Considering these results, it was observed that there is room to improve design approaches at high temperatures, which could be a valuable tool to define new design boundaries.