The influence of the axial magnetic field upon the low voltage electric arc in vacuum

The investigation of the influence of an axial magnetic field upon the characteristics of the large power and low voltage vacuum arc is presented. The tests were provided by help of an experimental setup able to provide asymmetrical and reproducible short-circuit currents up to 54 kA/sub rms/ at 1360 V/sub rms/. This current was interrupted in a monophase model of a vacuum switchgear, with the axial magnetic field generated by the interrupted current itself. Based on the experimental data, interesting results regarding the evolution of the arc voltage were achieved and original relationships for the evolution of the probability of breakdown failure, depending on the values of the current and axial magnetic field in the contact area were derived.