Numerical Analysis of Dependence of Airflow Distribution between Electrical Contacts with an Airflow Hole for Blowing Out of Break Arcs on Hole Diameter

A method was proposed by the authors to shorten duration of break arcs by ejecting airflow from an electrical contact surface into a contact gap. The effect of the airflow to shorten the arc duration was confirmed by experiments. However, since it was impossible to measure the airflow in the contact gap, its distribution was unknown. Therefore, numerical analyses of airflow distribution between the electrical contacts are performed. In this paper, analyzed results are shown for different contact geometries with different diameters of airflow holes. The analyzed results of the airflow in contact gaps are used to discuss experimental results. Following results are shown. When the airflow hole is larger, sufficient airflow velocity toward the outside in the radial direction is maintained near the opposed contact surface. For the case of smaller hole, the velocity distribution toward the outside in the radial direction exists only in the thin layer close to the opposed contact surface and the maximum airflow velocity is slower. The analyzed results confirm that the faster and thicker airflow efficiently pushes out the break arc for the case of larger hole, which shortens the arc duration.