An improved solution for the field near bundle conductors

The electric field near bundle conductors can be determined by replacing each conductor of the bundle by two filament conductors suitably displaced from each other and symmetrically placed with respect to the centre of the conductor they represent. The equipotential surface taking the place of the conductor will approach more closely a true circle than the corresponding surface arising from replacing each conductor by a single filament as described in a previous paper by the author. When the ratio r/R of the radius r of each conductor to the radius R of the bundle circle is small, say equal to 0.1 for a bundle of two conductors, the single-filament representation will be sufficiently accurate in calculating the electric field. For higher ratios of r/R, however, the twin-filament representation will yield better results. The position of the twin filaments relative to the original conductor is so arranged that, at the point of maximum surface gradient, the equipotential surface representing the conductor exactly coincides with the conductor. The paper deals first with the evaluation of the electric field outside the bundle conductors as well as the field at various points on the conductor surface. It is followed by applying the field outside the bundle conductors to the case of a triode and also to a 3-core belted-type cable. In the triode, the amplification factor as calculated by the method given in the paper is checked against that by Ollendorff for different values of screening fraction S. The field inside a 3-core cable leads to the determination of the thermal resistance of the cable, and the result compares favourably with that given by Simons.