Pre-breakdown photoelectric monitoring of AC gaps

Prebreakdown photoelectric monitoring of gaps is introduced. The photo and electric channels of measurements are discussed in detail. Photo and electric traces obtained for a point-to-plane air gap at natural temperature and pressure and under AC voltage are presented as examples. The gap geometry or gap length does not change the general character of the traces. Distinct relations between the photo and electric traces are presented and discussed relating to the breakdown mechanism. The presence of streamers at successively decreasing intervals leads to a plateauing in the photo trace which is a prebreakdown indicator. It is concluded that the proposed photoelectric monitoring provides a good tool for investigating the prebreakdown and breakdown processes of a gas gap