Comparison of Finite Difference Methods for Temperature Prediction in Axisymmetric HV Insulation Systems

The various finite difference methods available for solving steady-state and transient thermal fields in axi-symmetric systems of HV insulation are compared on the basis of economy of computer usage. The particular item used for the comparison was the through joint of a low-pressure oil-filled self-contained cable system, both naturally cooled and artificially cooled by water flow. Of the steady-state methods used, a modified form of Gaussian Elimination was seen to be most economical. However, this could not be used if non-linear effects were present. To cope with the latter the use of the transient Alternating Direction Implicit (ADL) method proved best. For transient fields the ADI was by far the best and guidance is given regarding the choice of time-step.