Digital Computer Calculation of the Potential and Its Gradient of a Twin Cylindrical Conductor

A knowledge of the electric field is required to estimate the onset voltages of corona breakdown for extra-high voltage lines with bundle conductors. A method is described for computing the potential and electric field in the gap between unipolar twin- bundle conductors and ground based on a charge simulation technique and the principle of images. In this method the charge on the conductors is represented by several lumped charges. Boundary conditions on the conductor's surface allow formulation of simultaneous equations, whose digital solution yields the assumed lumped charges, from which the potential and electric field are directly computed. The digital computer program provided values of the potential and electric field, magnitude, and direction, anywhere in the gap with an accuracy of 0.1 percent. The results of a sample calculation for an actual 345-kV conductor are given for varying parameters.