WHAT IS IORN CORE?

Commonly used transformer cores are generally made of silicon steel sheets. Silicon steel is a kind of steel containing silicon (silicon is also called silicon), and its silicon content ranges from 0.8 to 4.8%. Silicon steel is used as the core of the transformer because silicon steel itself is a magnetic material with strong magnetic permeability. In the energized coil, it can produce a greater magnetic induction intensity, thereby reducing the size of the transformer.

The actual transformer always operates in the alternating current state, and the power loss is generated not only in the resistance of the coil, but also in the core under the magnetization of the alternating current. The power loss in the iron core is usually called "iron loss", and the iron loss is caused by two reasons, one is "hysteresis loss" and the other is "eddy current loss".

Hysteresis loss is the iron loss caused by the presence of hysteresis in the process of magnetization of the iron core, and the magnitude of this loss is proportional to the area surrounded by the hysteresis loop of the material. The hysteresis loop of silicon steel is narrow, and the hysteresis loss of the core of the transformer is small, which can greatly reduce the degree of heating.

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

This is because the sheet core can reduce another type of iron loss, "eddy current loss". When the transformer works, there is an alternating current in the coil, and the magnetic flux it produces is, of course, alternating. This changed magnetic flux generates an induced current in the core. The induced current generated in the iron core circulates in a plane perpendicular to the direction of magnetic flux, so it is called eddy current. Eddy current losses also heat up the core. In order to reduce the eddy current loss, the iron core of the transformer is stacked with silicon steel sheets insulated from each other, so that the eddy current passes through a smaller cross-section in the narrow loop to increase the resistance on the eddy current path. 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 iron core used as a transformer is generally made of cold-rolled silicon steel sheet with a thickness of 0.35mm, which is cut into a long piece according to the size of the required iron core, and then overlapped into a "day" or "mouth" shape. Logically speaking, if the eddy current is reduced, the thinner the thickness of the silicon steel sheet, the narrower the spliced piece, the better the effect. This not only reduces eddy current losses, reduces temperature rise, but also saves the material used for silicon steel sheets. But in fact, when making silicon steel sheet iron core. It is not only from the above-mentioned favorable factors, because the production of the iron core in this way will greatly increase the man-hours, and also reduce the effective cross-section of the iron core. Therefore, when using silicon steel sheet to make transformer core, it is necessary to start from the specific situation, weigh the pros and cons, and choose the best size.

Transformers are made according to the principle of electromagnetic induction. There are two windings, a primary winding, and a secondary winding, wound around the closed core column. When the original winding is added to the AC supply voltage. The original Rao group flow has alternating current, and the establishment of magnetic potential, under the action of the magnetic potential, the main magnetic flux in the core will produce alternating main magnetic flux, the main magnetic flux in the core at the same time, the primary and secondary windings and closed due to electromagnetic induction in the primary and secondary windings respectively to produce induced electromotive force, as for why it can be boosted and reduced? Then it needs to be explained by Lenz's law, the magnetic flux generated by the induced current always hinders the change of the original magnetic flux, when the original magnetic flux increases, the magnetic flux generated by the induced current is opposite to 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 original winding, so the secondary winding has a low level of alternating voltage, so the core is the magnetic circuit part of the transformer, and the winding is the circuit part of the transformer.