MODELLING OF ARC DURATION AND EROSION IN ELECTRIACAL CONTACTS OF CIRCUIT BREAKERS

摘要

Dynamics of electrical and temperature fields in opening electrical contacts of circuit breakers is described by non-linear transient mathematical model. It takes into account interaction of electrical arc with contact surface, heat transfer with melting and evaporation of contact material, non-linear dependence of arc electrical and thermal conductivity. The dependence of arc duration and conditions of arc instability are found as functions of circuit parameters and properties of contact material. The new criterion of arc electrical conductivity is introduced which describes arc evolution. Results of calculation are compared with experimental data for AgCdO contacts. It is shown that duration of anode arc phase and erosion rate depend on the redistribution of heat flux components entering electrodes during arc evolution. Dependence of arc duration upon circuit inductance for various current is investigated.