Modelling of Streamer Breakdown in a 0.1 cm Air Gap using Positive Polarity DC in Subtropical Conditions

As there is an increase in the transmission of power occurring in tropical countries, it is imperative that research is conducted on the influence that high humidity has on the insulation characteristics of power lines and stations. Electrical streamers are known for being the precursor of sparks and is also known for performing the same function in the inception and propagation of lightning leaders. COMSOL Multiphysics allows for streamer discharges to be developed accurately using the plasma module. The article introduces the gaseous insulator air as well as electrical discharges and presents the results obtained from the numerical simulation conducted of a streamer initiating in the presence of space charge and propagating in a 0.1 cm air gap. The numerical model was used to investigate the relationship that exists between the breakdown voltage of air and various atmospheric conditions such as relative humidity and pressure. The results obtained from the numerical model showed that the breakdown voltage of the air gap shared a directly proportional relationship with the relative humidity and the atmospheric pressure of the system. This indicates that in high humidity environments for DC breakdown, the lightning attachment may have to be lower or higher due to attachment or ionization of the water molecules.