Partial Discharge Decomposition Characteristics of Typical Defects in the Gas Chamber of SF6 Insulated Ring Network Cabinet

The decomposition products of SF6 partial discharge (PD) were experimented to detect PD fault in the gas chamber of SF6 gas insulated ring network cabinet. The SF6 decomposition products and the decomposition characteristics of typical defects (i.e., metal protrusion and metal particle) were investigated. Two models of typical defects were constructed in the simulated gas chamber. Various discharge intensities were generated by applying different voltages, and the samples were collected and detected by gas chromatography mass spectrometry. Experimental results showed that the stable SF6 decomposition components under PD were CO2, SO2F2, SOF2, and SO2. The concentration of the four components increased with time and were saturated. In addition, the increase in discharge intensity significantly affected the decomposition process. Decomposition characteristics under different defects were analyzed according to the different electric field characteristics. Research showed that CO2 formation rate in the two kinds of defects under similar discharge intensity exhibited minimal difference. Furthermore, sulfide formation rate under metal protrusion defects was higher than that of metal particle defects. The same experiment was carried out in the ring network cabinet chamber, and the results were consistent with that in the simulation chamber.