Computer programs have definitely become indispensable for designing power transformer. Among several applications, computer programs are mostly used for electric field calculation and thus electrical insulation concerns. In consequence, studies based on analytical approach to basic studies of correlated problems have become even more important because they form the very basis of knowledge that is necessary to every transformer designer in view of taking all the advantages of computational analyses. On the other hand, one of the most important basic studies consists in the evaluation of voltage surge distribution along transformer windings for which the method of separation of variables has been extensively used thanks to some simplifying assumptions. With this aim, authors have developed and previously published works that show the applicability of an alternative and useful analytical method that is the method of the residues, which requires no simplification to be assumed. In this work, another important step is taken towards proofing the total applicability of this promising method that is through a practical problem. A comparison to the numerical method TLM (transmission line method) is also performed and concordance with TLM and experimental data confirms the proposal of the method of residues can be also applicable to several others problems of electromagnetism.