Study on factors influencing the characteristics of arc in DC contactors

The characteristics of arc in DC contactors are a major factor affecting the breaking performance of small-sized contactors. Based on the magneto hydrodynamics (MHD) model, this paper obtains the temporal and spatial distribution of arc temperature by taking DC arc as its research objective and H
₂
, N
₂
and He as arc extinguishing media. A removable arc chamber was adopted to build up a DC experimental circuit, in which a double-contact structure made of pure copper was selected, with a contact diameter of 10mm and a contact spacing of 2mm, to measure the influence of magnetic field, pressure and breaking speed on the characteristics of DC arc. The simulation and experimental results suggest that H
₂
has a stronger arc extinguishing capability than N
₂
and He when used as an arc extinguishing medium for switches; the increase in pressure contributes to the reduction in arcing time but the reduction is not monotonic, and a pressure of 3-4atm is desirable; the increase in magnetic flux density and breaking speed can effectively shorten the arcing time, and a breaking speed of 0.5m/s and magnetic flux density of 50mt are desirable.