Evaluation of PD Inception Voltage of a New Optically Transparent Silicone Elastomer at Different Parameters and Variable Testing Voltage Frequencies

摘要

A reliable assessment of the present condition of any electrical equipment commonly used in high voltage cable systems is playing an important part in achieving a sustainable development and upgrading of the power grid. This is going to be realized by an enhancement of monitoring and on-site testing. Partial discharge (PD) measurements and diagnosis are considered as a valid tool for evaluating the condition especially of cable systems. The lately discussed optical-only detection of PDs in high voltage cable accessories using integrated fiber optic sensors imply significant advantages over the electrical methods using a test setup according to IEC 60270 since the interference of electromagnetic disturbances is avoided. However, it is mandatory to use optically transparent insulating materials which have not been utilized in high voltage applications yet. Thus it is necessary to evaluate their suitability first. Furthermore, PD-measurements are commonly carried out at testing voltage frequencies differing from the power supply frequency of 50 Hz in order to lower the required amount of reactive power or using series resonance testing systems. At the same time larger cable lengths - necessary for the connection of off-shore wind farms and more and more present in urban agglomerations -demand alternative testing voltage frequencies in order to obtain diagnostically conclusive results. In this study the PD inception voltage (PDIV) of a commercially available transparent silicone elastomer is determined at different parameter sets and variable testing voltage frequencies. All measurements are performed on test objects with tip-plate configuration fabricated in the in-house laboratory using needles with defined tip radius as high voltage electrode and carried out according to the IEC 60270 standard. The parameters were chosen from the domain of the production and testing process.