IMPULSE INSULATION STRENGTHS OF LONG ROD-PLANE, CONDUCTOR BUNDLE-PLANE AIR GAPS AND INFLUENCE OF NEARBY CONDUCTIVE EARTHED OBJECTS ON THEM

摘要

The paper presents the results of the breakdown strength of a simulated four sub-conductor bundle (used in 765 kV system) and eight sub-conductor bundle to ground plane under standard switching impulses of 250 μs/2500 μs as well as under non-standard switching impulses with varying front times. It has been observed mat there exists a minimum breakdown voltage for each gap length at a particular wave front. The breakdown strength of rod-plane gaps at different gap lengths was also studied. The results of the breakdown strength, critical flashover value and critical front time of 4 & 8 sub-conductor bundle are compared together with the results of the rod-plane gap. A critical analysis of these results has resulted in the emperical formulae for critical front time and critical flashover voltages for all the gap configurations, hi addition, the influence of the earthed objects in the vicinity of these gaps on their switching impulse strengths was experimentally determined and critically analysed.