Partial Discharge Measurement During Interfacial Tracking Degradation Under 50 Hz Voltage Excitation

Modern high-voltage solid insulation is a system of multiple dielectric layers of different properties brought together to provide the best stress relief. Thus, understanding the degradation in interfaces of these layers, is essential for assessing the dielectric performance of the insulation system. This paper focuses on the interfacial degradation of SiR-SiR under AC stress using Partial Discharge (PD) measurement to assess the mechanism and its visual characterisation. Results from this work will aid in understanding the propagation of interfacial tracks, especially around stress grading in HV assets. This study used coplanar needle-plane geometry to analyse the degradation of solid dielectric interfaces. SiR sheets were pressed together using transparent acrylic plates and nylon bolts, which were tightened using a torque wrench to control the contact pressure. After five hours of testing at 12 kV
rms
50 Hz, the tests showed electrical degradation in the material's surface (tracking) and the bulk (treeing) with extensions between 444 µm and 817 µm, depending on the sample and its pressure. These results suggested that the contact pressure affects how the degradation develops at the interface.