The impact of conductor material on the critical diameter of particle produced in overhead line conductor clashing
Abstract
Conductor clashing of overhead lines, particles eruption and potentially ignition of dry biomass to the soil under or around the transmission line, is a phenomenon that has not been studied sufficiently. Due to the collision of two conductors on different potentials at the point where contact or electric arc is established, electric energy is converted into heat energy. The large amount of heat causes melting and evaporation of metal, thereby creating sparks falling on the ground. The pressure of vaporized metal can be high enough to eject molten metal as small particles. Some of these droplets will ignite and burn, while others will simply fall to the ground. Metal particles are naturally cooled by convection and radiation. When the particle falls to the biomass on the ground it can cause fire if it has enough temperature and amount of heat. The critical diameter is the least diameter of the particle caused by conductor clashing that will, in spite of the particle cooling on the way, be sufficient to ignite the biomass on the ground. The results of the particle critical diameter for the aluminum and copper conductors in the same conditions are presented and compared. For both types of conductors the impact of biomass humidity, height of the collision, etc. are analysed. The results show that the copper particles in the same conditions bring a greater ignition risk due to their higher heat capacity.
