1994 Volume 114 Issue 11 Pages 1168-1174
Arc interruption in a high voltage circuit breaker is usually performed in gas blast to an arc column through a nozzle throat. The authors have pointed out in various types of the flat air blast quenching chamber that better interruption performance was found when a sharp minimum of electron density was brought about at the nozzle throat around current zero and it was realized in an orifice type of nozzle.
This paper describes effect of air flow passage on current interruption ability in the flat type of arc chamber with the orifice nozzle. The following three kinds of air blast are tested by modifying the flow passage: (a) oblique blast in which air flow passes through the arc column at an angle with it, (b) both-side blast in which air flow passes along both sides of the column, this corresponding to a usual gas blast method, (c) single-side blast in which air flow passes along only one side of the arc column. The flat type of quenching chamber makes easy for measurements of the pressure rise distribution and of the electron density by microwave at 70 GHz in the nozzle throat space.
The obtained results are summarized as follows.
(1) The oblique blast type has more excellent interruption capability than the both-side and single-side blast type.
(2) The pressure rise in the upstream region of the nozzle throat as well as the electron density decay at the nozzle throat are both remarkable in the oblique blast type. These are brought about by a nozzle clogging-like action and by effective arc energy dissipation due to direct cross of air flow with the arc column.