Magnetic saturation at short-circuit tests on power transformers

The post-set and pre-set short-circuit test methods for power transformers are discussed. KEMA´s testing experience with special attention to the pre-set method, inrush currents and premagnetization, are highlighted. By means of premagnetization inrush currents can be avoided to a large extend The saturation of the supply side transformers leads to a distortion of the supply side voltage, thus preventing saturation of the test objects. The different saturation modes of the transformer under test are briefly mentioned in relation to the dynamic stresses on the windings.