Estimating the Effect of Overvoltage Results from Excitation Current Chopping in Short-circuit Transformer

여자전류 재단에 따른 단락 시험용 변압기의 절연영향 평가

The residual flux in transformer's iron cores leads to a distortion of short-circuit current occasionally. And some considerable distortion may have effect on the validation of the test results. To avoid the substantial distortion, a suitable pretest is performed before the actual test. In case of applying this method there must be excessive overvoltage due to switching of an unloaded transformer and chopping of an excitation current. The purpose of this paper is estimate that the effect of the overvoltage results from this phenomenon on insulation performance of short-circuit transformer.