Resolve the core in the transformer

The core is the basic missing of the power transformer, which is composed of core lamination, insulation and core structural parts. The core body is composed of magnetic steel strip with high permeability, in order to make different windings can induce a voltage proportional to the number of turns, the magnetic flux of the two winding chains is required to be equal, which requires an iron core made of materials with high permeability in the winding, and try to make all the magnetic flux in the core and two winding chains, and make only one winding chain magnetic flux as little as possible.

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

The core lamination is composed of electrical magnetic steel strip stacking or winding, and the core structure is mainly composed of clamp, foot, brace plate, pull belt, pull screw and press nail. The structural parts ensure that the laminates are fully clamped to form a complete and solid core structure. There are insulation parts between the laminate and the clamp, the foot pad, the stay plate, the pull belt and the pull plate. The lamination ground lead is connected to the clamp or to the external reliable ground through the mailbox. The core is not allowed to be grounded at multiple points. The lower clamp of the large transformer core is positioned by the positioning nail of the mailbox, and the positioning piece on the upper part of the core is positioned with the mailbox.

In order to reduce the no-load loss and no-load current of the transformer, the iron core is made of cold-rolled electrical magnetic steel strip with high permeability magnetic grain orientation, and a series of measures are also taken in the structure. The inclined joint non-porous binding of the iron core is adopted to adapt to the orientation of cold-rolled magnetic steel sheet and the core structure of magnetic circuit symmetry.

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

Transformer core is generally divided into two categories, namely shell core and core core. And each type of iron core is divided into two kinds of laminated iron core and rolled iron core. The laminated iron core is formed by the laminated electrical steel strip one by one; Coil core is made by continuous winding of strip material in the appropriate shape mold of the winding machine. In addition, there is a double frame core, that is, a size frame structure, but now because of the use of high-quality cold-rolled electrical magnetic steel strips, the width of the steel strip can meet the requirements of the width of the core column and the iron yoke, it is rarely used double frame (size frame) core. In addition, there are new double-frame and multi-frame structures, such as single-phase double-frame and three-phase four-frame structures.

According to the number of phases of the transformer, the core of the single-phase transformer is collectively referred to as the single-phase core, and the core of the three-phase transformer is collectively referred to as the three-phase core; It can also be classified according to the number of columns and frames of the transformer core.