Behavior of GIS epoxy insulators with metallic inclusions

Investigations of the breakdown behavior of epoxy insulation systems with controlled defects based on floating metallic inclusions and protrusions fixed to cast-in electrodes were carried out. Spacers made with filled resins and blunt embedded metallic needles failed at lower stress than spacers with sharp needles. However, the results may be compromised by the presence of a multiplicity of defect sites. The manufacture of filled epoxy GIS (gas insulated switchgear) spacers with controlled defects proved difficult to control. The newly developed XIPD (X-ray induced partial discharge) system with 0.01 pC sensitivity was instrumental in identifying the existence of inadvertent defects which could prove more severe than the intended defects