Concept for Determination of a ‘Health Index’ for Field-Aged Composite Insulators by Thomas Schiml and Fabian Lehretz

HTV silicone is the preferred material for composite insulators used on overhead lines due to its hydrophobicity, hydrophobicity recovery and hydrophobicity transfer. While these properties have been verified in standardized test procedures, resistance to ageing during operation is also critical since this can lead to insulator failure. TenneT, a cross-border TSO, applies a systematic approach to assess reliability using a ‘Health Index’ for each grid component. This presentation explains how this concept is applied to new lines being equipped with polymer insulators. It also discusses choice of samples as well as assessment of laboratory test results and provides specific examples showing the practicability and reliability of this process.