Abstract :
Recently, no-load losses P and noise n of transformer cores have been reduced by replacing the former single-step-lap (SSL) joints by multistep-lap (MSL) joints. On the other hand, the application of MSL in model cores was found not only to decrease P and n, but in some cases they increase. The aim of this paper is the investigation of the difference between SSL and MSL with respect to local magnetic conditions at joint regions and their relevance for global conditions in the core. The results show that the joint is the key region of the transformer core, affecting its dynamical behavior in a distinct way. To minimize the iron losses and the noise of the core, the step lap number N should be chosen carefully to avoid the appearance of "virtual temporary air gaps".
Keywords :
acoustic noise; joining processes; losses; noise abatement; power transformers; transformer cores; transformer windings; dynamical behavior; global conditions; joint regions; local magnetic conditions; multistep-lap joint power transformer cores behaviour; no-load losses reduction; noise reduction; single-step-lap joints; step lap number; virtual temporary air gaps; Acoustic noise; Core loss; Lamination; Magnetic cores; Magnetic flux; Magnetostriction; Power system reliability; Power transformers; Steel; Transformer cores;
