The actual transformer always works in the AC state, and the power loss occurs not only in the resistance of the coil but also in the core of the alternating current magnetization. Usually the power loss in the iron core is called "iron loss", and the iron loss is formed by two reasons, one is "hysteresis loss" and the other is "eddy current loss".

Hysteresis loss is the iron loss that occurs during the magnetization of the core due to hysteresis. The magnitude of this loss is proportional to the area enclosed by the hysteresis loop of the material. The hysteresis loop of silicon steel is narrow, and the core hysteresis loss of the transformer is small, which can greatly reduce the degree of heat generation.

Since silicon steel has the above advantages, why not use a whole piece of silicon steel as the iron core, but also process it into a sheet?

This is because the sheet core can reduce another type of iron loss - "eddy current loss". When the transformer is working, there is an alternating current in the coil, and the magnetic flux it generates is of course alternating. This changed magnetic flux induces an induced current in the core. The induced current that occurs in the core circulates in a plane perpendicular to the direction of the magnetic flux, so it is called eddy current. The same eddy current loss causes the core to heat up. In order to reduce the eddy current loss, the core of the transformer is laminated with silicon steel sheets insulated from each other, so that the eddy current flows through the narrow cross section to increase the resistance on the eddy current path; together, the silicon in the silicon steel makes The resistivity of the material increases and also acts to reduce eddy currents.

Used as the core of the transformer, a 0.35mm thick cold-rolled silicon steel sheet is generally used, and it is cut into a long piece according to the scale of the required core, and then overlapped into a "day" shape or a "mouth" shape. In theory, if the eddy current is reduced, the thinner the thickness of the silicon steel sheet, the narrower the spliced strip, and the better the effect. This not only reduces the eddy current loss, reduces the temperature rise, but also saves the silicon steel sheet. But actually when manufacturing silicon steel sheet iron core. It is not only from the above-mentioned favorable factors, but because of the manufacture of the iron core, the working hours are greatly increased, and the useful cross section of the iron core is also reduced. Therefore, when manufacturing a transformer core with a silicon steel sheet, it is necessary to start from the specific situation, weigh the pros and cons, and select the best scale.

The transformer is made according to the principle of electromagnetic induction. There are two windings, one primary winding and one secondary winding on the closed iron core. When the original winding is connected with the AC power supply voltage, the original Rao has a flow. The current is changed, and the magnetic potential is established. Under the effect of the magnetic potential, alternating main magnetic flux occurs in the iron core, and the main magnetic flux passes through together in the iron core, and the second winding is closed due to electromagnetic induction. The effect is that the induced electromotive force occurs in the first and second windings respectively. As for why it can boost and step down? Then it is necessary to explain the magnetic flux generated by the induced current, which always prevents the change of the original magnetic flux. When the original magnetic flux is added, the magnetic flux of the induced current is opposite to that of the original magnetic flux, that is, the induced magnetic flux generated by the secondary winding is opposite to the main magnetic flux generated by the primary winding, so the secondary winding exhibits a low level. The alternating voltage is such that the core is the magnetic circuit of the transformer and the winding is the circuit part of the transformer.