Electrical Breakdown Study in CO2 and CO2-O2 Mixtures in AC, DC and Pulsed Electric Fields at 0.1–1 MPa Pressure

In this paper, the results of AC, DC and 2/160 μS impulse electrical breakdown experiments of CO
₂
and CO
₂
-O
₂
mixtures in weak and strongly non-uniform fields are presented. In weakly non-uniform fields, the electrical breakdown field approximately follows 11 [(kV)/(cm bar)] when stressed with both AC and DC (positive and negative) waveforms. For positive impulse, the breakdown voltage is higher and the time lag to breakdown is scattered, indicating a lack of starting electrons from CO
₂
gas. The breakdown strengths of CO
₂
-O
₂
(10-30%) mixtures is investigated. On application of negative polarity impulse, the breakdown strength is significantly higher than positive impulse in the measured pressure range of 0.3-0.7 MPa in strongly non-uniform fields, contrary to that seen during breakdown in weakly non-uniform fields. Breakdown voltage for negative impulse is further enhanced in a mixture of CO
₂
-O
₂
(80-20%).