Negative and positive impulse corona development along cylindrical insulator surfaces

Streamer propagatio studies i a non-uniform gap under both positive and negative impulse voltages are presented, i the presence of cylindrical insulators and air alone. It is sho that the negative corona is highly constrained i all cases i compariso to positive corona, at comparable voltage levels i relatio to breakdo n voltages. Under both polarities the presence of PTFE promotes streamers to the largest extent. As evinced by photographs, positive corona i all cases studied sho marked branching compared to negative corona here hardly any branching occurs. The presence of glass retards the gro th of corona under negative polarity, hereas for positive polarity corona gro th i the presence of glass is comparable to that i air.