Electric Arc Model, for High Power Interrupters

The switching tests, to which are subjected the interrupters, consume a large amount of power and materials. The ante-calculation of the arc voltage or the post-arc current is practically impossible to be analytically achieved. A solution is the switching process modeling, by taking into account the apparatus characteristics, such as dissipated power and the time constants. Within the framework of this paper, a model of the switching phenomena in an AC low voltage vacuum circuit breaker is presented, aiming to better predict the apparatus behaviour. The model is based on a very attentive experimental investigation of the switching processes taking place at high currents interruption. Based on the experimental investigations results, statistically processed, the parameters of the electric arc model, from the Mayr's equation can be calculated. Finally, the arc voltage, the post-arc current and the transient recovery voltage, which represent the circuit breaker stresses in the switching process, are calculated. The obtained results are validated by comparison with the experimental ones and they can be used to predict the behaviour of other similar circuit breaker of new type or to optimise an existing apparatus