Analysis of the Influence of Water Trees Geometrics' Shapes in the Level of Degradation of the Power Cable's Insulation

Water tree is the major problem that causes unscheduled interruptions, due to degradation of power cable insulation. Therefore, many techniques have been developed to detect water tree at their early stages and to increase the cable efficiency by reducing the time frame of the cable failure. The loss current technique is a suitable method for investigating this degradation, for the cable degradation by water tree inserts harmonics components in the leakage current. This technique aims to estimate the performance parameters of insulation deterioration from the supply voltage and leakage current measured that flows through the insulation carried out in hot-line cables without interrupting the service. This paper presents the influence of different geometric shapes of the water tree submitted to different voltage stress and different frequency in the values of various parameters that have been used to predict and indicate the operational status of power cables. The results confirm that the geometric shape of water tree has influence in the level of degradation and that the stress increased has been used to identify water trees in their initial stages.