Aging of vacuum insulation and insulation with gas at low pressure due to electric breakdown

The paper discusses and compares the rates of aging (destruction) of insulation systems insulated with gas at low pressure and vacuum under conditions of frequent electrical breakdowns. Helium (He) was used as a gas. The insulation system in which the aging rates were tested had the same dimensions and CuCr and CuBi electrodes of the Rogowski shape were used. The electrode contact material was selected in such a manner so that its composition corresponds to the material used for vacuum switches manufacture. To assess the speed of aging, i.e., the length of a lifetime, a mathematical-statistical model was developed, the effectiveness of which was verified by an experimental procedure. The experimental procedure was carried out under well-controlled laboratory conditions. All instruments used were certified. The combined measurement uncertainty was less than 7%. Based on the graphical assessment and the analytical procedure, the obtained quantitative results show that vacuum insulation ages about twice as slowly as insulation with low pressure gas. This result is explained by the mechanism of breakdown initiation in gases at low pressure and in the vacuum.