The Electrical Characteristics of Gas Blast Circuit Breaker Arcs at Very High Currents

The Electrical characteristics of very high current (3-95kA) gas blast interruptor arcs are presented for a number of different operating conditions (air and SF6, carbon and Cu-W electrodes, Cu, PTFE and steel nozzles). The current: voltage and pressure increas: arc power characteristics are interpreted in terms of the arc interaction with the imposed flow, pronounced increases in radiactive losses due to severe electrode evaporation and increased conduction due to nozzle ablation. An approximate scheme for normalising gas flow arc characteristics at very high current levels is also examined.