Why Do Silicon Steel Sheets in Transformers Need To Be Insulated From Each Other?

Two key points:
1. Eddy current loss: Due to the fact that ferromagnetic materials (such as silicon steel sheets) are usually conductive materials, when the coil is energized with alternating current, the magnetic flux inside the iron core changes accordingly, causing eddy current (eddy current) to be induced in the iron core. The eddy current generates heat dissipation, which is called eddy current loss. To prevent eddy current loss, silicon can be added to the steel to increase the material resistance (- increase the resistivity of ferromagnetic materials); Alternatively, the iron core can be formed by laminating silicon steel sheets with surface insulation and a thickness of 0.35 or 0.5mm (reducing the S of the ferromagnetic material and thereby increasing the eddy current resistance), which can effectively prevent eddy currents. In addition, the cross-sectional area of ferromagnetic materials transformed into silicon steel sheets decreases (the total area is basically constant), resulting in a decrease in the induced eddy current electromotive force. According to P=U ^ 2/R, the overall eddy current loss decreases.
2. Resistance is proportional to resistivity and inversely proportional to the equivalent cross-sectional area of the material.