Algorithm and software for shortening heat run test of oil-immersed power transformers

Abstract

One of the type tests on power transformers is heat run test, which checks that the characteristic winding and oil temperatures are below allowed values. This is necessary to prevent accelerated ageing and shortening of the transformer life if the temperatures are higher than the allowed values. In addition to the user's clear interest, manufacturers are also interested in the results of heat run tests, as they can verify and improve the accuracy of calculation methods and software [1]. Then they can increase the accuracy and reduce the safety margins of calculation methods, so they can change transformer construction and achieve temperatures that are much closer to the allowed ones. As the result of that, they can reduce material and production costs. The minimal test is defined by the IEC standard [2]. Due to the great mass and consequent great thermal capacity of the transformer parts, heat run tests take a very long time. The paper presents an algorithm, and its software implementation, which reduce the occupancy of test station, energy consumption and the total cost of performing heat run tests.