The biggest difference between oil-immersed transformer and dry-type transformer is that there is no “oil”, and because oil is liquid, with liquidity, oil-immersed transformer must have a shell, the shell is transformer oil, the oil is immersed in the transformer coil, the transformer coil is not visible from the outside; And dry type transformer without oil, there is no need for the shell, can directly see the transformer coil; Another characteristic is that the oil-immersed transformer has an oil pillow on it, and the transformer oil is stored inside, but now the new oil-immersed transformer also has no oil pillow.
All power transformers have iron cores for magnetic circuits and windings for circuits. And the biggest difference is in “oil” and “dry”. That is to say, the two cooling medium is different, the former is transformer oil (and other oil such as β oil, of course) as the cooling and insulation medium, the latter is air or other gases such as SF6 as the cooling medium. The transformer is to place a body composed of an iron core and a winding in a tank filled with transformer oil. The iron core and windings are often coated with epoxy resin. There is also a now used more non-encapsulated type, winding with special insulating paper and then impregnated special insulating paint, to prevent the winding or iron core damp.
In order to facilitate heat dissipation of oil-immersed transformer, that is, to facilitate the flow of heat dissipation of internal insulating oil, the radiator is designed externally, just like the heat sink, while the dry transformer does not have this radiator, and the heat dissipation depends on the fan under the transformer coil.
Oil immersed transformer due to the need for fire prevention, generally installed in a separate transformer indoor or outdoor, and dry transformer must be installed in the indoor, generally installed in the distribution room.
In terms of output and consumption, the current dry transformer voltage grade is only 35kV, and the capacity is relatively small for oil transformer, about 2500kVA. And because the manufacturing process of dry transformer is relatively complex with the same voltage level and capacity of oil transformer, the cost is also high. So at the moment from the use of oil or more. But because of the dry environmental protection, flame retardant, impact resistance and so on advantages, and often used in high requirements of indoor power supply and distribution places, such as hotels, office buildings, high-rise buildings and so on.
It can be seen that the dry transformer and the oil transformer have their own advantages and disadvantages. The oil transformer has low cost and convenient maintenance, but it is flammable and explosive. Due to its good fire resistance, the dry transformer can be installed in the load center to reduce voltage loss and power loss. But the dry variable price is high, the volume is large, moisture-proof and dustproof is poor, and the noise is big.
Post time: Aug-02-2021
