EXPERIMENTAL AND NUMERICAL-STUDIES OF ARC RESTRIKES IN LOW-VOLTAGE CIRCUIT-BREAKERS

This paper is devoted to the study of the are restrike phenomenon in l ow-voltage circuit breakers, We focused our interest on the type of ar e restrike that can be described as a sudden reignition in the arcing contact region while the are was situated in the quenching chamber a f ew tens of microseconds before it occurs, Our experimental investigati ons have established that the critical arcing contact region is still crossed by a so-called residual current on the order of several ampere s, A gas temperature around 4200 K was derived from electrical measure ments in this region before the are restrike occurrence, We also demon strate that the restrike takes place through the growth of the remaini ng current of several amperes in the arcing contact region. A numerica l approach was carried out with a two-dimensional hydrodynamic code in order to simulate the gas behavior in the arcing contact region befor e and during the are restrike phenomenon, The same temperature as the measured one is calculated just before the restrike, It is demonstrate d that the current density appears to be the most sensible quantity, A critical value of 5 A/cm(2) was calculated.