The biggest advantage of amorphous alloy core distribution transformers is that the no-load loss value is extremely low. The ultimate assurance of no-load loss values is a core issue to be considered throughout the design process. When the product structure is arranged, in addition to the fact that the amorphous alloy core itself is not affected by the external force, the characteristic parameters of the amorphous alloy must be accurately and reasonably selected in the calculation. In addition to this design idea, the following three requirements must be followed:
(1) Due to the low saturation magnetic density of amorphous alloy materials, the rated magnetic flux density should not be chosen too high during product design. Usually, the flux loss density of 1.3~1.35T can be obtained to obtain better no-load loss value.
(2) The thickness of the amorphous alloy material is only 0.03mm, so the lamination factor can only reach 82%~86%.
(3) In order to enable users to obtain the benefits of maintenance-free or less maintenance, the products of amorphous alloy distribution transformers are now designed as a fully sealed structure.
Transformer amorphous alloy structure characteristics
The amorphous alloy with outstanding magnetic permeability is used as a core material for manufacturing a transformer, and finally a very low loss value can be obtained. But it has many characteristics that must be guaranteed and considered in design and manufacturing. The main body reflects the following aspects:
(1) The amorphous alloy sheet material has a high hardness and is difficult to shear with a conventional tool, so the design should be considered to reduce the amount of shear.
(2) The thickness of the amorphous alloy monolith is extremely thin, and the surface of the material is not very flat, and the core filling factor is low.
(3) Amorphous alloys are very sensitive to mechanical stress. In the design of the structure, the traditional design with the iron core as the main load-bearing structural member must be avoided.
(4) In order to obtain excellent low loss characteristics, the amorphous alloy iron chip must be annealed.
(5) From the electrical performance. In order to reduce the amount of shear of the iron chip, the core of the whole product is composed of four separate core frames, and each phase winding is placed on two separate frames of the magnetic circuit. In addition to the fundamental magnetic flux, the magnetic flux in each frame also has the presence of a third harmonic flux. In the two winding core frames of one winding, the third harmonic flux is exactly opposite in phase, numerically. Equal, therefore, the sum of the third harmonic flux vectors in each set of windings is zero. If the primary side is D-connected, there is a loop of three harmonic currents. When the induced secondary side voltage waveform is on, there will be no third harmonic voltage component.
According to the above analysis, the most reasonable structure of the three-phase amorphous alloy distribution transformer is: iron core, which consists of four separate core frames in the same plane to form a three-phase five-column type, which must be annealed with a crossed iron yoke. The seam has a rectangular cross section. The windings are rectangular in cross section and can be individually wound, double or multi-layer rectangular. The fuel tank is a fully sealed, maintenance-free corrugated structure.
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