Application of Miniature Pressure Gauges for fast, transient Pressure Measurement in Arc Chambers

摘要

Electrical switching devices may be equipped with an arc chamber in order to extinguish the switching arc between open contacts. The switching capacity of such a device may be strongly influenced by the gas flow around the switching arc. In this paper a pressure measurement set-up is described which can be used to detect the dominant physical gas flow effects in simplified arc chambers and furthermore to measure the pressure distribution. Because of the hot arc plasma and its direct contact with the active pressure element, together with the high electromagnetically interference (EMI) and the high limiting frequency a special screening and a calibration of a standard pressure sensor was required. Finite Element Simulations with FEMLAB proved the negligible influence of the installed pressure measurement to the gas flow in the arc chamber as well as the effective reduction of the temperature stress to the pressure gauge to acceptable values. Measurements with four installed pressure devices and an optical arc observation system showed the dominant influence of the gas flow to the arc motion at the special arrangement. Typical unsteady gas flow processes like pressure waves and their propagation with accompanying effects like changing of the shape of travelling pressure waves were observed.