X-ray Direct Radiography in GIS Testing

In this paper, the typical defects that were found in testing of operating gas insulated switch(GIS) using X-ray real-time direct radiography(DR) were introduced. The bus line of 110 kV GIS, equipped in certain transformer substation of Yunnan, was found unusual sound while operating. Via DR testing, we found the broken insulator supporting the horizontal post of B-phase and the oblique post vertical to the horizontal one. Contrasting between the obtained X-ray photographs and the real inner parts of GIS showed that the results obtained using DR were completely in accordance with the real one. These conclude that DR testing can give intuitive and qualitative results to the inner flaws of GIS, such as the cracks and assembling defects. These results provide the most effective evidences for making repair schedule and therefore save repairing period.