kerosene gas phase drying equipment insulation structure of voltage transformer
Voltage transformer can be divided into dry type, pouring type, oil immersed type and gas type according to the insulation medium. The insulation structure of voltage transformer adopts different ways according to different voltage levels and different use environments. Generally, the low voltage transformer for measurement is dry type, and the high voltage or ultra-high voltage sealed gas insulated transformer (such as sulfur hexafluoride) is also dry type.
It is suitable for 35kV and above cast voltage transformer. Compared with the traditional oil immersed and air filled transformers, the epoxy resin casting transformer has the advantages of no oil, no gas, no shell, life-long maintenance free, good insulation performance and so on. It is a kind of transformer widely used in the world.
Dry insulation structure is simple to manufacture, low cost, but the insulation strength is not high, so the voltage of this structure is generally not more than 380V. QZ type enamelled round copper wire is used as the conductor, and the insulation materials used in the insulation structure mainly include insulating paper, glass fiber cloth tape, phenolic plastic, etc. The insulation between the coil and the iron core is made of bakelite or plastic framework, the interlayer insulation and the main insulation between the primary and secondary coils are generally made of yellow wax silk or polyester film. The insulation between the ring core and coil of instrument voltage transformer is usually made of insulating paperboard, and then wrapped with one or two layers of glass ribbon, yellow silk or polyester film tape. Dry type is simple in structure but large in volume. It is only suitable for low voltage indoor devices or instrument voltage transformers of 10kV and below.
In the design of transformer, the insulation part generally adopts the traditional design method, that is, the inspection and statistics method is used to determine the insulation life of transformer. In recent years, modern design methods have appeared in transformer insulation design methods, such as finite element analysis, reliability design technology and optimization design technology. With the development of computer technology, large professional analysis and optimization software is used for analysis and design. The scheme obtained by modern design method is more economical and reasonable than that by traditional design method.
As the modern design method is still in the development, the specific content of modern design method is difficult to determine, but there are many mature methods, which can be summarized as follows: optimization design, finite element analysis, reliability analysis, modeling design, value engineering, design expert system; computer aided design, etc. Moreover, these methods can be used to form a variety of methods with unique application objects, such as reliability optimization design.