Effect of Smoke on Corona and Breakdown Characteristics of Air Under Positive and Negative DC Voltages

Wildfires generate a large amount of smoke which primarily contains fine particles that can participate in gas discharge mechanisms under dc electric fields. This paper presents an experimental study evaluating corona discharge and breakdown characteristics of air under various levels of smoke at positive and negative dc voltages. Discharge pulse repetition rate, average discharge current, and partial discharge inception voltage are investigated as corona discharge characteristics of a needle-plane air gap while the breakdown voltage is measured as breakdown characteristics of air in a uniform electric field. The experimental findings show that the positive and negative dc breakdown voltage of a uniform-field air gap under the considered smoke levels is not significant. Additionally, except for the average discharge current, the impact of smoke on negative dc corona characteristics is negligible. The average discharge current under negative dc voltage shows a decrease for increasing smoke densities. The effect of smoke on positive dc corona is terminal and caused by the particle deposition from smoke on electrodes.