Calculations of breakdown voltage of rod-plane air gaps in the presence of water streams

A breakdown model of rod-plane air gaps in the presence of water streams has been established. Water streams which do not fully cross air-gaps are considered. This model involves the breakup length and surface conductivity of a water stream, the stream´s diameter, the number of the water droplets in the remaining air gap and the distance between two adjacent water droplets. The breakdown voltage is considered in two parts: one being the voltage drop along the water stream surface, and the other the voltage drop across the remaining air gap. To study the two components of voltage drop, the equivalent surface conductivity of a water stream and the voltage-current characteristics between two water droplets were investigated. Additionally, theoretical and experimental results are compared and it has been found that under the conditions considered, the breakdown voltages are predictable to within 13%. Evidence regarding the impact of radial dispersion of droplets and their distortion on the breakdown process is considered.