Mobile vacuum kerosene gas phase drying equipment and its application VPD equipment is still the drying technology of large transformers recognized and widely used all over the world. But it can only be used in the factory workshop. How to carry out drying treatment more effectively when assembling transformers (including repairing transformers) on the site of power stations has been perplexing the workers in the transformer industry and drying treatment on the site of power stations all over the world. It is the dream of many people to move VPD equipment to the site and carry out vapor phase drying treatment at the site of the power station.

According to the data we checked, the production process of assembling transformer (ASA) at the site of power station began in 1992 by Toshiba company of Japan. China's Changzhou Toshiba company began producing ASA in 2002. It has been nearly five or six years since Chinese transformer manufacturers began to produce giant transformers by means of "disassembly, transportation and on-site assembly", and now it shows a trend of "vigorous development".

There are two basic processes for producing transformers by ASA. We call it "non hygroscopic assembly" and "hygroscopic assembly", or "continuous operation".

There are two kinds of non hygroscopic assembly. One is the plastic film protection method, and the other is the process time protection method. The former is wrapped with special engineering plastics on the surface of transformer windings and related insulating parts for protection from moisture. Some plastic films are directly installed in the transformer and will not be removed. The latter is a process similar to our "body finishing", that is, in the process of disassembly, packing and assembly, the work is carried out in strict accordance with the temperature and humidity conditions and within a controlled time.

Once the control time is reached, immediately enter the vacuum tank for heating and vacuum protection. For on-site assembly, the transformer oil tank needs to be temporarily covered for protection. This process method, only in the factory disassembly and packing process, will last for more than 20 days. It also takes more than 20 days to assemble on site. The process and duration of such repeated protection are described as "miserable" by specific manufacturers.

Continuous operation assembly is to allow continuous work or even three shifts in the process of disassembly, packing and on-site assembly. Therefore, the disassembly and packing in the factory will not exceed one week. The assembly on site can also be completed in a week or a little more. This greatly improves the production efficiency. However, the assembly of continuous operation obviously brings a problem of re drying.

In the process of manufacturing and assembling the transformer on site, we adopt the process of continuous operation. Hot oil circulation was also used as a drying method at the beginning, but the effect was not good. In order to improve efficiency and ensure quality; Through careful analysis and careful decision-making; Mobile vapor phase drying equipment is selected to dry and assemble the transformer. The mobile vapor phase drying treatment equipment has been successfully designed and manufactured, and has been successfully used in the process treatment of giant assembled transformer on site. At present, four sets of mobile vapor phase drying equipment have been manufactured, and more than 20 giant transformers have been dried on the site of the power station.