Impact of quality of glass cap-and-pin insulators on life cycle costs and proposals for screening tests

摘要

During the latest years there has been a large scale restructuring in the market for toughened glassinsulators. Manufacturers have moved or opened new factories and several new producers haveentered the toughened glass cap-and-pin insulator market. Service experience and specialinvestigations have revealed that there is a great variance in the manufacturing quality of insulatorsfrom new producers, although they formally withstood standard IEC requirements. Thus, today it isnot possible to distinguish the low quality from the high quality insulators relying on standard IECtests only and this in turn has a direct influence on life cycle costs (LCC). Two parts of the LCC areincreased in the discussed case, i.e. quality assurance and un-scheduled maintenance. The goal of thiswork was to identify suitable and practical additional test procedures that can be used to verify thequality of glass insulators including:1. Impulse puncture withstand test in air (steep-front test)2. Mechanical failing load3. RIV tests in dry (standard procedure) and wetted (non-standard procedure) conditions4. Residual strength tests.The main practical output of the present work is that in the tests on “low quality” insulators 60-80% ofthe batch was shattered both in the mechanical, thermal-mechanical and steep-front tests. Thus theresult confirms a need for future standardization work within CIGRE/IEC to prevent such insulators toreach the power utilities.