A study of the various phases of the break in a low-voltage circuit breaker thanks to the magnetic camera

Abstract

By analysing the magnetic induction created by the arc motion from the outside of a breaking system at numerous points, it is possible to determine the position of the average line of current that magnetically represents the arc. This method is called the `magnetic camera' method. It had to be adapted to the circuit breaker studied here. Thanks to the method three phases of the course of the electrical arc are highlighted for a typical experiment: expansion of the arc, commutation from the mobile contact onto the lower rail and displacement through the splitter plates. In order to be more precise about the duration of the commutation phase, during which more than a single line of current must exist, an improved model of the arc motion has been developed.