Temperature profile of progressive damaged overhead electrical conductors

Abstract

The Brazilian transmission system is characterized by installations that average 20years of operation. Competitiveness of the energy sector, lack of resources for new investments and the aging of the system lead to the necessity of not only to reform but also to optimize it in order to face the increasing demand of the Brazilian energy market. The overhead electrical conductor is naturally the most important element on the transport of electrical energy and requires careful predictive and preventive maintenance programs. Therefore, it is of fundamental importance to predict the operational life of overhead electrical conductors using mathematical models so that their energy transport capacity can be optimized. However, it is necessary to validate such models by means of test programs so that their predictions can be trusted. One of the most important factors on the structural decay of overhead electrical conductors is the variation of the temperature profile in the event of the rupture of one or more of its Aluminum wires by fatigue or fretting. Therefore, models that include this temperature variation must be validated through test programs that can experimentally establish a mathematical relationship which considers effects such as contact resistance, material thermo-mechanical properties modification, annealing of the material and the presence of defects. The objective of this work is to evaluate the effect of progressive Aluminum wire rupture on the temperature profile of an ACSR (Aluminum Conductor Steel Reinforced) overhead electrical conductor, not only on the section of the damage but also along the length of the conductor. A test procedure was developed and performed to establish this effect. Results were compared to a mathematical model and showed that the temperature profile dependency of the increasing rupture of Aluminum wires is not linear and includes effects other than the cross section loss.