A new approach is developed to inspect the internal pressure within the vacuum switchgear by no means of magnet-exciting coil, micro-discharge threshold voltage Ud and field emission threshold voltage Ud all of which are available in laboratory. Experimental results show that internal pressure is a function of the ratio of the micro-discharge threshold voltage to the field emission threshold voltage i.e., Ud/Ue. By this method, the internal pressure in the range of 10^0-10^-4 Pa within vacuum chambers can be inspected without magnet-exciting coil which is required in conventional magnetron discharge method.
