A surface resistivity probe for assessing solid insulators in GIS [gas insulated switchgear]

The changes in surface characteristics after a spacer has been exposed to a large amount of SF₆ decomposition products for a short period of time, which is similar to conditions during fault repair, are described. The design and construction of a prototype surface electrical resistivity probe which can be used to assess the reusability of contaminated solid insulators are also described. This special, conformal surface resistivity probe was designed to carry out the demanding measurements on contoured surfaces. These measurements must be carried out under typical field conditions, and specifics of the critical experimental parameters (voltage, geometry, humidity) must be recognized. The probes have been used successfully to assess the condition of suspect spacers exposed to a high concentration of by-products following a power fault