|Release time: 2018-04-11 Click times: 1045 times|
| The iron core is basically not found in power transformers, and is composed of iron core laminations, insulation parts, and iron core structural parts. The core body is composed of a magnetic steel strip with high magnetic permeability. In order for different windings to induce voltages that are proportional to the number of turns, it is necessary to equalize the magnetic flux of the two winding chains, which requires that the windings have very high magnetic permeability. For a core made of high material, try to keep all the magnetic flux in the core and two winding chains, and make as little as possible the magnetic flux that is combined with only one winding chain. |
In order to reduce the excitation current, the core is made into a closed magnetic circuit, and the core is the skeleton of the coil. It is an extremely important part for the electromagnetic performance, mechanical strength and transformer noise of the transformer.
The core lamination is made by stacking or winding electrical magnetic steel strips. The core structural parts are mainly composed of clamps, feet, support plates, draw belts, pull screws and nails. The structural parts ensure that the laminations are fully clamped to form a complete and solid core structure. There are insulation members between the laminations and the clips, the feet, the support plates, the pull straps and the pull plates. The core core leads the ground lead to the clamp or to the ground through the mailbox. The core cannot be grounded at multiple points. The clamps under the iron core of large transformers are positioned by the positioning pins of the mailbox, and the positioning members on the support plate on the upper part of the iron core cooperate with the mailbox.
In order to reduce the no-load loss and no-load current of the transformer, in addition to the high-permeability grain-oriented cold-rolled electrical magnetic steel strips, the iron core also adopts a series of structurally corresponding measures, using oblique seams to bind the core without holes. In order to adapt to the directivity of cold-rolled oriented magnetic steel sheets and the use of a core structure with magnetic symmetry.
The part of the core covered by the winding becomes the core post, and the other part that is not surrounded by the winding and forms the closed path of the magnetic flux becomes the iron yoke. The space defined by the core post and the yoke is a core window, and the size of the core window is related to the number of windings and the cross-sectional area.
Transformer cores are generally divided into two categories, namely shell-type cores and core-type cores. Each type of iron core is divided into two types: stacked iron core and rolled iron core. Among them, the sheet-shaped electrical steel strips are stacked one by one to become a stacked iron core; the rolled core is continuously wound by using a belt-shaped material on a winding machine with an appropriate shape mold. In addition, there are double-frame iron cores, that is, large and small frame structures. However, since high-quality cold-rolled electrical magnetic steel strips are used, the width of the steel strips can meet the requirements of the width of the core and the yoke. )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.
According to the number of transformer phases, the cores of single-phase transformers are collectively referred to as single-phase cores, and the cores of three-phase transformers are collectively referred to as three-phase cores.
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