Why Do Transformer Cores Use Square Electrical Steel Plates?

GNEE New Material Electrical Steel Plate

Power losses in the iron core include "hysteresis loss" and "eddy current loss". Hysteresis loss is the energy consumed by repetitively magnetized domains in an alternating magnetic field. The hysteresis loss per unit volume is proportional to the area of the hysteresis loop and the frequency f of the alternating magnetic field (V is the volume of the magnetic conductor). Therefore, by selecting magnetic materials with narrow hysteresis loops, the hysteresis loss of the iron core can be reduced. Materials such as electrical steel used in transformers and motors have low hysteresis losses.
Eddy current loss The alternating magnetic flux produces an induced electromotive force in the iron core, causing circulating currents called eddy currents, which circulate in a plane perpendicular to the magnetic flux. The power loss caused by eddy currents; therefore, the eddy currents of the iron core can be reduced by increasing the resistance of the iron core. loss. Stacking sheets of electrical steel insulated from an iron core allows eddy currents to pass through a resistor along a short eddy current path in a long, narrow circuit. At the same time, the silicon in silicon steel increases the resistivity of the material and also plays a role in reducing eddy currents.

The biggest reason for choosing a square iron core is the convenience of winding coils. The iron core with this shape can be wound separately on the machine and then set on the iron core, which is suitable for mass production in actual projects. Of course, the iron core with this shape The core also has the disadvantage of having an air gap between the laminations, causing magnetic flux leakage.
In fact, there is also a round iron core. This type of iron core is directly rolled from electrical steel strips. It has no air gap, small magnetic leakage and better magnetic properties than square ones. However, due to its troublesome coil winding, it is not easy to be mechanized and mass-produced. It has fewer applications and is usually used for precision current transformers (unlike power transformers, which are usually used for measurements).

Transformer Cores Use Electrical Steel