Reliable method for accurate measurements of the breakdown voltage in microgaps

The up-to-date tendency of compact design of low/medium voltage equipment implies micrometer distances between the active parts. In order to reduce losses and prevent operational failure of the devices under such conditions, knowledge on the breakdown voltage is essential. However, measurements of the breakdown voltage in microgaps remains quite delicate experiment, mainly because of difficulties related to the accurate definition of the distance between the electrodes. To overcome these limitations, we propose here a reliable method based on measurements of the current amplitude and phase between current and applied voltage for AC signals. It is shown that when contact between the two electrodes occurs the current amplitude increases substantially and the phase changes abruptly to zero. Thus, no arbitrary conditions are needed to define the contact point. The system is well-defined and the procedure accuracy improved.