The presented study deals with the influence of the contacts materials on
the evolution of the arc in low voltage circuit breakers. The commutation
from the mobile contact onto the electrode is especially investigated in
order to improve the breaking device performances. Hence, to preserve the
qualities of the contact, the arc must leave this area as soon as possible.
To undertake this study, several diagnostics are implemented. A measuring
device is composed of magnetic induction sensors located outside the
chamber. It allows the determination of the position and the volume of the
arc during the breaking. Optical (ultra-speed camera) and electrical
measurements are also performed with the technical support of Schneider
Electric. Different current values (assumed peak current of 3 kA, 8 kA and
12 kA) and different natures of materials composing the electrical contacts have
been tested. Copper contacts, different contacts on silver base obtained
with different processes have been used. Experimental results show the
influence of these various parameters on the arc volume and on the transfer
of the arc towards the quenching chamber. Indeed, different dynamic
behaviors are observed during the current transfer phase.