• Categories:Industry News
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• Time of issue:2018-01-31
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(Summary description)
　　The iron core is the basic part of the power transformer, which is composed of iron core laminations, insulating parts and iron core structural parts. The core body is composed of magnetic steel strip with high magnetic permeability. In order to make different windings induce a voltage proportional to the number of turns, the magnetic fluxes of the two windings are required to be equal, which requires a very high magnetic permeability in the windings. For the iron core made of high material, try to make all the magnetic flux in the iron core link with the two windings, and make the magnetic flux linked with only one winding as little as possible.

　　In order to reduce the excitation current, the iron core is made into a closed magnetic circuit, and the iron core is the skeleton for installing the coil. It is an extremely important part for the electromagnetic performance, mechanical strength and transformer noise of the transformer.

　　The iron core laminations are made by stacking or winding electrical magnetic steel strips. The iron core structural parts are mainly composed of clamps, feet, supporting plates, pull straps, pull screws and pressure nails. The structural parts ensure sufficient clamping of the laminations to form a complete and firm core structure. There are insulating parts between the laminated sheet and the clamping parts, the feet, the supporting plate, the draw band and the draw plate. The iron core lamination leads to the ground lead to connect to the clamp or to the external reliable grounding through the mailbox. The iron core is not allowed to be grounded at multiple points. The lower clamping piece of the large transformer iron core is positioned by the positioning nails of the mailbox, and the positioning piece on the supporting plate on the upper part of the iron core is positioned in coordination with the mailbox.

　　In order to reduce the no-load loss and no-load current of the transformer, the core is not only made of cold-rolled electrical magnetic steel strip with high magnetic permeability and grain orientation, but also a series of measures have been taken in the structure, and the core is tied with mitered joints without holes. , In order to adapt to the directionality of cold-rolled oriented magnetic steel sheet and the use of symmetrical magnetic circuit core structure.

　　The part of the iron core covered by the winding becomes the iron core column, and the other part that is not enclosed by the winding to form a closed magnetic flux path becomes the iron yoke. The space determined by the iron core column and the iron yoke is the iron core window, and the size of the iron core window is related to the number of windings and the cross-sectional area.

　　Transformer cores are generally divided into two categories, namely shell cores and core cores. And each type of core is divided into two types: stacked core and wound core. Among them, a laminated core is formed by stacking sheet-like electrical steel strips one by one; the wound core is continuously wound by a strip-shaped material in a suitable shape die on a winding machine. In addition, there is a double-frame iron core, that is, a large and small frame structure. However, now that the high-quality cold-rolled electrical magnetic steel strips are used, the width of the steel strip can meet the requirements of the width of the core column and the iron yoke, so the double frame (large and small frame) is rarely used. )core. In addition, there are new types of double-frame and multi-frame structures, such as single-phase double-frame and three-phase four-frame structures.

　　If divided by the number of transformer phases, the cores of single-phase transformers are collectively called single-phase cores, and the cores of three-phase transformers are collectively called three-phase cores; they can also be classified according to the number of columns and frame numbers of the transformer core.