
Core is the basic power transformer is not seen by the core laminated, insulation and the core structure and other components. The core body is made of a magnetic tape with a high magnetic permeability. In order to make the different windings sense the voltage proportional to the number of turns, the magnetic flux of the two windings is equal, which requires the permeability High material manufacturing core, as far as possible so that all the magnetic flux in the core and the two winding chain, and only one winding and the magnetic flux as much as possible. To reduce the excitation current, the core made a closed magnetic circuit, the core is to install the coil of the skeleton, for the transformer electromagnetic performance, mechanical strength and transformer noise is extremely important components. The core laminations are formed by stacking or winding the electric magnetic steel strip. The core structure is mainly composed of clamps, pad feet, brackets, pulls, pull screws and nails. The structural parts ensure that the laminations are fully clamped to form a complete and secure core structure. Laminated and clip pieces, pad feet, brace, pull and pull between the plates are insulated. Core stacking leads to the ground lead to the folder or through the mailbox to the external reliable grounding, the core does not allow the existence of multi-point grounding. Large-scale transformer core clip under the use of the positioning of the positioning of the nail, the upper part of the core plate on the positioning of the positioning and mail with the positioning.
In order to reduce the transformer no-load loss and no-load current, the core in addition to the use of high permeability magnetic grain oriented cold-rolled electrical steel strip manufacturing, the structure is also a corresponding series of measures to adopt oblique joints without holes , To adapt to the orientation of the cold rolled oriented magnetic steel sheet and the use of magnetic circuit symmetry of the core structure.
The portion where the core is covered by the winding becomes a core pillar, and the other portion where the magnetic flux is not surrounded by the winding is formed into an iron yoke. The space defined by the core column and the iron yoke is the core window, and the size of the core window is related to the number and cross-sectional area of ??the winding.
Transformer core is generally divided into two categories, namely the shell core and heart-shaped core. And each type of core is divided into stacked core and volume core two. Which is formed by the sheet-like electrical steel strip-by-piece stacking core; roll core is a belt-like material in the winding machine on the appropriate shape of the mold continuously wound from the system. In addition, there are double-frame core, that is, the size of the box structure, but now because of the use of high-quality cold-rolled electrical steel strip, the width of the strip has been able to meet the requirements of the core and the length of the yoke, so rarely use double- )core. In addition, there are new double-frame and multi-frame structure, such as single-phase dual-box and three-phase four-frame structure.
If the number of transformer according to the number of single-phase transformer iron core collectively referred to as single-phase core, three-phase transformer core collectively referred to as three-phase core; can also press the transformer core column number, frame number and so on.