Research On Preparation And Properties Of Fe₇₈Si₉B₁₃ Amorphous Cores Used For Power Distribution Transformers

The amorphous distribution transformers which use new energy-saving materials, iron based amorphous strip as core had been widely applied because of their outstanding low no-load loss characteristics. The study of homemade iron based amorphous strip and its core would provide strong support to the development of the amorphous distribution transformer in our country.In this dissertation, the homemade Fe78Si9Bi3amorphous strip and its core had been systematically investigated. Firstly, the structure, properties and heat treatment process of Fe78Si9B13amorphous strip were studied. Secondly, the distribution transformers core of Fe78Si9B13amorphous were designed, and the preparation technology, the corrosion properties under different circumstances, the magnetic properties and temperature characteristic of Fe78Si9B13amorphous cores were studied. Lastly, on the base of previous studies, the examples of315KVA amorphous distribution transformer were designed.The studies show that the best encapsulation adhesive concentration of epoxy resin was2%, the magnetic properties of magnetization curves, permeability curves, excitation curves and loss curves of Fe78Si9B13amorphous core after superposition were between the single core, which show clearly that make a transformer core with performance up to the standard through combining cores by single cores, which were prepared by the low width homemade amorphous ribbons is practicable. An orange precipitate was produced in solution when the amorphous cores in distilled water,0.1mol/L NaCl solution under the conditions of corrosion test, respectively. And the magnetization of amorphous core becomes difficult. But the soft magnetic properties of amorphous cores basically unchanged when it soak in methyl silicone oil for30days.The lancing structures of the amorphous cores are transforming non crystal to crystal after incised by the wire cutting. Also it had different influence on soft magnetic properties of the incised cores with different process of wire cutting. Furthermore, it shows that the soft magnetic properties of incised cores with "big V pattern" decreased in minimum. But it is hard to make an amorphous distribution transformer core with performance up to the standard through incised cores. Rectangular hysteresis loop can be obtained by means of longitudinal magnetic heat treatment for Fe78Si9B13amorphous cores, and squareness ratio Br/Bm increases to0.94while it’s only0.58without longitudinal magnetic heat treatment, structure relaxation plays a little influence on soft magnetic properties of amorphous cores with longitudinal magnetic heat treatment, the soft magnetic properties of amorphous cores performs an excellent stability. Using manufacturing method of winding coil for Fe78Si9B13amorphous cores after longitudinal magnetic heat treatment, SH15-M315/10amorphous distribution transformer can be manufactured, whose performance are consensus on the national standards.