Oil-immersed test transformer, as the name suggests, the internal use of insulating oil for insulation and arc extinguishing. It has the advantages of low cost, fast voltage rise, strong voltage resistance, easy and cheap maintenance. If inadvertently damaged during use, it can be disassembled to replace the copper core or insulating oil, so the cost of purchase and use is relatively low. But because the insulating oil is installed inside, the equipment is relatively bulky, not conducive to outdoor use, there are also some disadvantages, such as oil pollution.
The inflatable test transformer uses SF6 gas for insulation and arc extinguishing. Because it is inflatable, it has the advantages of small size, light weight, cleanliness, and no oil contamination. However, if the internal gas escapes, maintenance is very difficult, only to return to the factory to deal with, the use of more trouble. At the same time, the cost of this equipment is relatively high, resulting in rising prices.
Dry-type transformer using internal core and epoxy resin casting technology manufacturing, one-piece molding, no need to inflate and insulating oil. It is low cost and cheap, but large and heavy. At the same time, because it is one-piece casting, if the internal parts are damaged, it is almost impossible to repair. Users need to be extra careful during use. So generally small projects prefer to use this kind of equipment.
Overall, oil-immersed transformers, gas-filled transformers and dry-type transformers three test transformers have their own advantages and disadvantages, to meet the different needs of different power workers.