Practical Aspects in the Application of Conductive Barriers to Field Controlled Air Gaps

The principles of an optimization technique to improve the dielectric strength of nonuniform air gaps, by mitigating the field intensity of the most stressed point(s) in the gap, is presented in this paper. The approach consists of modifying the gap geometry and, if required, of adding a minimum number of conductive barriers of proper shapes. The technique is applied to some practical and relatively complex geometries, namely an air insulated wall bushing and the top electrode of a high voltage transformer. Experimental verifications are performed for the former configuration. Application of the optimization scheme to outdoor geometries is also discussed.