Safe distance approach dimensioning-application to high voltage live works

Nowadays, the industrialization and economic development require more continuity, availability and quality of the electric energy. Thus, producers and distributors are obligated to perform a maximum of maintenance and repairing works on overhead lines and substations while being under voltage. Approach distances to be respected must be determined by the most rigorous way in order to ensure a total security of the operators in charge of these works. Several authors propose different empirical formulas of the statistical breakdown voltage U50 as a function of the gap Du in rod plane electrode configuration under normalized surge overvoltages. Safe distances to be respected in high voltage line works are determined on the basis of these statistical breakdown voltages. In the present work, a comparative survey will be achieved between the proposed approaches, and their use in the minimal distance approach assessment techniques recommended by IEC 61–472 and IEEE Std 516 standards. These techniques will be coupled with electric field numerical calculations in order to foresee an extension of these techniques to live works with non conventional tools.