Methodology for determining the degree of magnetic induction of transformers with sinusoidal magnetic flux

This study aims to reduce the losses in the magnetic circuit steel of electrical machines. These losses amount up to 5% of the generated electricity, do not depend on the load, and can increase over the operational lifetime of the equipment. For the effective design and construction of transformers with low no-load losses, total losses in steel are minimized by optimizing the crystal grain size and thickness of core sheets, improving the steel texture and magnetic circuit design. However, these measures influence the hysteresis, classical eddy current, and anomalous eddy current components of losses in steel in different ways, which cannot effectively minimize total losses. Herein, a method for determining the three components of losses was developed using the modernized three-frequency method, which considers the dependence of the hysteresis loss coefficient on frequency. An equation for correcting this coefficient was derived. It is demonstrated that the indicator of the degree of magnetic induction given in most current studies in the expression for eddy current anomalous losses has become irrelevant. A method for calculating this indicator for the core of a specific transformer was presented, which uses the loss components and total losses in steel determined from using the three-frequency method at a reduced primary voltage. For the transformer of interest, the degree of magnetic induction in anomalous losses was 1.88. This study can be used in the design of dry-type and oil-immersed transformers of different powers operating with sinusoidal magnetic flux.