Calculation of Winding Losses in Shell-Form Transformers for Improved Accuracy and Reliability Part-1: Calculation Procedure and Program Description

This paper presents a 3D program developed by Westinghouse Electric Corporation for accurate calculation of eddy and circulating current losses in windings of shell-form power transformers. Comparisons made between the 3D results, test results, and other analytical results on a number of commercial transformers prove the validity-of the program and the superior accuracy it provides. As described in the paper, the 3D program calculates, in addition, the relative contributions of the individual coils to the total winding losses. Such information is used to arrive at effective winding design methods for reducing load losses. The program also calculates magnitudes of the highest circulating currents and locations of the most heavily loaded strands. Such information is very important in designing reliable transformers by avoiding winding hot spots. This paper is divided into two parts. In this part of the paper the 3D loss program is described. First, the front-end of the program and the computer communication system used to submit, execute, and returns the results of, the program are described. This is followed by a concise description of the calculation procedure used in the program and the output of the program.