Performance Analysis of Methods at Estimating Insulated Cables Degradation

Abstract

The quality of electricity supply, among other issues, deals with continuity indicators as one of the most important factors for the characterization of an adequate service as far as power quality is concerned. In this context, one of the major problems responsible for the unscheduled interruptions is related to the degradation of electrical cables insulation and the well-known water tree effect emerges as an important cause for the deterioration of their insulation layer. If this phenomenon happens, a large loss of insulating properties of dielectric material used to build up such component will occur. In light of these facts, the development of procedures to evaluate, predict, and indicate the operational status of operating cables shows itself highly attractive in order to improve the quality and reliability of energy supply. Focusing on this subject, this paper presents a synthesis of existing methods and a new trend towards the mentioned matter. By using experimental measurements, carried out in medium voltage commercial operating cables in a distribution utility throughout non-invasive approach, applied voltage and insulating leakage currents are obtained to support the analysis. The data are used to obtain degradation indexes to estimate the cables physical operational conditions and the indicators found are further considered in the view of the effectiveness of the strategies for the diagnosis purposes.