Magnetic properties and their relation to the no-load noise and no-load losses of large power transformers

Abstract

The performance of the no-load losses and core noise of large power transformers (LPT) can be attributed to the magnetic properties of the deployed grain-oriented electrical steel (GOES) material. Measurements of different GOES materials have led to findings about their performance. Four LPT cores, each with a mass of 40 metric tons, were manufactured out of 187 GOES coils with the same material grade but with different properties. Before the transformer cores were manufactured, each of the deployed GOES coils was measured with an in-house coil measurement system (CMS) to obtain the specific power losses and the magnetostriction. This paper shows a first comparison between the measured GOES coils magnetic properties and LPTs. First, the measured magnetostriction of the GOES coils and their predictability on core noise of the LPTs are evaluated. In addition, the assessment of the GOES coils specific power losses and the no-load losses of the LPT units are shown.