S series power transformer adopts the horizontal mounting method to insert and solder directly on the printed circuit board, whose coil plane is perpendicular to the printed circuit plane, and the magnetic force lines generated by the coil are parallel to the printed circuit plane. Therefore, the impact of transformer leakage on the printed circuit is less than that of the stand-mounted transformer.

In order to let users have a quantitative estimation of the leakage of this series of transformers, so as to arrange the printed circuit board more reasonably, we commissioned the Department of Electronic Engineering of a major university in China to make a leakage test for this series of power transformers of different powers, and according to the experimental data, the contour distribution of the three components of leakage, Bx, By and Bz, was drawn respectively, and the theoretical analysis of the experimental results was made.