Gaseous by-products of a CF3I-CO2 gas mixture under lightning impulse and AC breakdowns

This paper examines the use of a CF3I-CO2 gas mixture as an environmentally friendly insulation medium in high voltage gas insulated equipment. The gaseous by-products of a 30:70% CF3I:CO2 (Trifluoroiodomethane – Carbon dioxide) gas mixture are examined after being subjected to HV lightning impulse breakdowns and sustained HV AC breakdown. The experimental results obtained from direct gas samples taken before and after high voltage breakdown in a point-plane electrode configuration indicate the presence of a small quantity of by-products. The main by-products detected were CF4 or C2F6O3 or both. Other possible by-products may include CHF3, C3F8, C2HF5 and C2F5I, however, it is difficult to accurately detect these by-products because of the high quantities of CF3I and CO2 in the original gas mixture