Induced fields, charges and currents on a lineman engaged in transmission-line insulator washing

Abstract

This paper aims to calculate the distribution of the field, induced charges and currents on a lineman engaged in power transmission line insulator washing. The method of analysis is based on the charge simulation technique. The lineman is modeled by small sphere for the head and a large sphere for the body. For simplicity, the tower is chosen to be of the duct type and the insulator of the suspension type. The transmission line conductor is simulated by finite and semi-infinite line charges to account for the nonuniform distribution of conductor charge resulting from the suspension insulator and the supporting tower. As the purity of the washing water is high, the water spray is simulated by a thin conducting stick extending between the column insulator and the lineman sitting on the crossarm of the tower. This represents a three-dimensional field problem and care has been devoted in the choice of the number and coordinates of charges simulating the tower, the insulator, the conductor, the water spray and the lineman. The induced currents increase as the lineman approaches the insulator with the suspended line conductor. These currents are higher than those for insulated lineman and may exceed safe limits.