ELECTRIC FIELD MEASUREMENT IN ROD-DISCONTINUED PLANE AIR GAPS USING DISTRIBUTED CAPACITY PROBE

The present experimental carried out investigations aimed at elucidating the effect of earth discontinuity on the breakdown voltage of short rod-plane air gap (80 to 160 mm) under negative lightning impulses (-1.2/50?s). We also carried out investigations on electric field measurement on the surface of a discontinuous plane of a rod-plane air gap arrangement. For this purpose, we used a probe with distributed capacity, under negative lightning applied impulse voltage. The probe is incorporated on the same level of plane surface. The interface locally reinforces the electric field. The electric field increases at the interface may lead to a discharge between the high voltage rode and the interface. In the vicinity of the interface, we observe a kind of discontinuity in the evolution of the electric field intensity. This one becomes greater than the value obtained in the case of gaps with homogeneous plane earth.