The actual transformer is always operating in an AC state and the power loss is 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." The iron loss is caused by two factors. One is "hysteresis loss" and the other is "eddy current loss."
The hysteresis loss is the core loss caused by hysteresis in the magnetization process. 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 iron core 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 a core, but also to process it into sheets?
This is because the sheet iron core can reduce another kind 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 changing flux creates induced currents in the core. The induced current generated in the iron core circulates in a plane perpendicular to the direction of the magnetic flux, so it is called eddy current. Eddy current losses also cause the iron core to heat up. In order to reduce the eddy current loss, the transformer core is laminated with silicon steel sheets insulated from each other, so that the eddy currents in the narrow loop, through a smaller cross-section, to increase the resistance of the eddy current path; at the same time, silicon in silicon steel makes The increased resistivity of the material also acts to reduce eddy currents.
As a transformer core, a 0.35mm thick cold-rolled silicon steel sheet is generally used. According to the required size of the iron core, it is cut into a shape sheet and then overlapped into a “Japanese†shape or an “I†shape. In theory, if the eddy current is reduced, the thinner the silicon steel sheet is, the narrower the spliced ​​sheet is, and the better the effect is. This not only reduces the eddy current loss, reduces the temperature rise, but also saves the use of silicon steel sheet. But when actually making silicon steel cores. Not only from the favorable factors mentioned above, because the production of iron cores, it will greatly increase man-hours, but also reduce the effective cross-section of the core. Therefore, when making transformer cores from silicon steel sheets, it is necessary to weigh the pros and cons and choose the best size from the specific conditions.
The transformer is based on the principle of electromagnetic induction. Two windings, one primary winding, and one secondary winding are wound on the closed iron core. When the primary winding is supplied with AC power voltage. The original Rao group has alternating currents, and the establishment of magnetic potential, in the magnetic potential under the core will produce the alternating main magnetic flux, the main flux in the iron core at the same time through, {chain} one. The secondary winding is closed due to the induction of electromagnetic induction induced in the first and second windings, as to why it can step up and step down. It needs to be explained by the Lenz's law that 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 to say twice. The induced magnetic flux generated by the winding is opposite to the main flux generated by the primary winding, so the secondary winding has a low level of alternating voltage. So the iron core is the magnetic circuit part of the transformer, and the winding is the circuit part of the transformer.
Weathering steel, i.e. atmospheric corrosion-resistant steel(Corten Steel), is a series of low-alloy steel between ordinary steel and stainless steel. Weathering steel is made of ordinary carbon steel with a small amount of corrosion-resistant elements such as copper and nickel. It has the characteristics of toughness, plasticity, forming, welding and cutting, abrasion, high temperature and fatigue resistance of high-quality steel. The weathering resistance is 2-8 times of ordinary carbon steel and the coating performance is 1.5-10 times of ordinary carbon steel. At the same time, it has the characteristics of rust resistance, corrosion resistance, life extension, thinning and consumption reduction, labor saving and energy saving. Weathering steel is mainly used in railway, vehicle, bridge, tower, photovoltaic, high-speed engineering and other steel structures exposed to the atmosphere for a long time. It is used to manufacture containers, railway vehicles, oil derricks, seaport buildings, oil production platforms and containers containing hydrogen sulfide corrosive medium in chemical and petroleum equipme.
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