Rational Analysis of Electric Fields in Live Line Working

As voltage of electrical transmission systems increases, live line maintenance by the barehand method becomes increasingly necessary to meet the requirements of system reliability. Of more importance is its value to the workman in permitting him to use power and hand tools without the strain which would be encountered with the long, heavy, hot line tools required at these voltages. Protection of the workman from exposure to high-voltage gradients and body currents is easily attained through Faraday cage-type shielding, as has been proved by an extensive test program described in this and companion papers. This paper develops a method of predicting voltage gradients and body currents utilizing both analytical and numerical techniques in the solution of Laplace´s equation. The results are compared with field measurements and excellent agreement is obtained. The method described can therefore be used to predict both currents and gradients for new designs and voltage levels as well as for existing designs and voltages.