Between Oil Immersed Transformers and Dry Type Transformers

Oil immersed transformers, different from dry type transformers, are transformers whose iron cores and windings are submerged in insulating liquid. Compared with dry type transformers, oil immersed transformers' iron cores and iron rings adopt vacuum drying, which is among the most significant differences between oil immersed transformers and dry type transformers. Though both being frequently-used transformers, oil immersed transformers and dry type transformers are different in many respects and either kind of transformer has its own advantages and disadvantages.

One of the differences between oil immersed transformers and dry type transformers is their application environments. Oil immersed transformers, especially oil immersed distribution transformer, due to their transformation ratio of 20KV/500KV or 20KV/220KV, can be well applied at high voltages, which is one of their huge advantages and makes them appropriate to heat-engine plants' booster stations. But the disadvantage is that oil immersed transformers' application is restricted when faced with relatively lower voltages. By contrast with that, dry type transformers are suitable to serve as middle and small-capacity transformers of the illumination and electronic circuits in upscale places like office buildings and guild halls, because of their transformation ratio which is 100000V/400V.
Oil immersed transformers' voltage classes can be very high and their floor spaces are smaller than those of dry type transformers. In addition, oil immersed transformers are of better heat dissipation potential and more extensive operation places when compared with dry type ones, which is an advantage enabling them to be applied out of doors. However, oil immersed transformers may produce oil injection or flame if meetting with machine breakdowns, which makes them inappropriate to use indoors. In this respect, dry type transformers' advantages are revealed just enough. Dry type transformers are clean, safe and they are of superior fire resistance, which makes them appropriate to places with stringent fire protection requirements.
Price is another factor we should take into account. In terms of same capacities, the procurement price of dry type transformers is much higher than that of oil immersed transformers. Though oil immersed transformers have price advantages, dry type transformers can withstand short circuits better and are more easy to install. Also, the heat resistance of dry type transformers is an advantage which oil immersed transformers can not match. But one of dry type transformers' disadvantages is that they must be operated at rated capacity, which is not so flexible for using. By contrast, oil immersed transformers are of better overload capacity and their service conditions are not restricted by the rated capacity too much.
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