On-site Drying Technology of Disassembly-transportated UHV AC Transformer

UHV AC transformer is one of the most difficult equipment in the transportation of electric power large equipment. Its transportation weight and dimension have reached the limit of highway transportation. At present, it is impossible to transport by railway, and it is very difficult to coordinate highway transportation. It is often necessary to reconstruct roads, strengthen bridges and so on. There are many factors that affect transportation, not only the transportation period and safety risk control are difficult, but also the transportation cost is very high. Limited by transportation conditions in some areas, the location of substation is directly affected. In order to solve the transportation problem, the large power transformer usually adopts the disassembly transportation and site assembly scheme, that is, the overall transportation of transformer is transformed into the transportation of its components, so as to avoid the problem of overall transportation overweight and large size. A single UHV Transformer is assembled on site. The assembly process is basically the same as that in the factory, which takes nearly 50 days. It is inevitable that the insulation parts of the transformer body will be damped. Therefore, the product must be dried on site. In this paper, several effective on-site drying methods are compared and analyzed. The advantages and disadvantages of each method are evaluated by comprehensive comparison, and then an ideal and practical on-site drying method is sought or selected. Finally, it is concluded that the mobile gas phase drying technology has a good drying effect on the spot, which is very suitable for the field drying of special and large-scale field assembled transformers. This paper focuses on the key technologies of mobile vacuum vapor phase drying method, including drying process, temperature control measures, moisture content control of transformer insulation and evaluation methods.