The integrity of the electrical insulation is of greatest importance in the reliability of high voltage equipment. Failure of the insulation system may cause an interruption of service, or in worst case a complete damage of the equipment with a costly replacement.
The research work aims at developing practical and reliable methods that can diagnose the degradation status of the electrical insulation. The results from diagnostic methods can be used in long-term maintenance strategies but also for short-term estimates of the failure risk in relation to the risk.
The diagnostic techniques under investigation are based on measurement of different kind of dielectric response. Low-frequency dielectric spectroscopy is developed as a general tool to diagnose degraded insulation systems. The applicability of high-frequency methods for a more precise localization of defect insulation is under development. Partial discharge activity is measured and analyzed when the insulation system contain voids, delaminations, cracks or over-stressed surfaces, etc., that may cause local discharges.
Research on new composite materials with SiC for field grading applications is performed as an industrial Ph.D. project at ABB. This would give a possibility to optimize the field control in highly stressed devices like, for example, cable terminations.