Suitable properties of stress grading materials

The scope of this paper is to present, both from a theoretical and a practical point of view, some aspects involved in stress grading in the general configuration where insulated high voltage conductors pass through a grounded screen. Particular attention is devoted to the rules governing the potential and the field distribution in the case of stress grading resistive materials. A discussion is proposed about the possible use of constant conductivity materials. Finally, practical considerations are listed as basic rules for optimizing the grading effect.