The Role of Wire Size in Negative Electrical Discharge at High Temperature

Negative corona onset and sparkover voltages in air are shown to be affected by temperature, density, and the pipe-to-wire ratio of radii when using concentric cylindrical electrodes. Use of large wires at high temperatures demonstrates that onset of electrical discharge occurs at voltages significantly less than those predictable by earlier theory and that sparkover occurs at voltages considerably greater than those anticipated. Theory is presented to account for the results obtained.