Dependence of Partial Discharge Characteristics on Applied Voltage Frequency with IEC(b) Electrode System

Abstract

The significance of on-site insulation diagnosis has been increasing year by year to deal with tremendous amount of aged high voltage power apparatus in utility companies. On-site diagnostic methods based on partial discharge (PD) measurement using resonant high-voltage supply are promising technique because resonant power supplies are smaller, lighter and having higher testing capacities than those with conventional power source. However, the frequency of a resonant power supply can be different from the conventional power frequency because it depends on a capacitance of the test objects. In order to develop diagnostic methods with resonant power supply, we should clarify the PD characteristics of defects in high voltage insulation under higher power frequencies. As a first step of the development of the diagnosis, we investigated the frequency dependence of PD characteristics with an IEC(b) electrode system as a model defect for delamination between insulating materials and metallic electrodes. This paper describes the PD characteristics under the power frequencies from 25Hz to 1000Hz. As a result, we found that important PD characteristics such as the maximum apparent discharge magnitude are almost independent of the applied voltage frequency within the experimental conditions except those for frequencies higher than 500Hz.