There are two types of Transformer depending upon type of medium used for cooling of Transformers:-
1. Oil cooled/ Liquid Transformers
2. Air cooled/ Dry Transformers
In oil type transformers insulating oil (Mineral Oil) is used for cooling for Transformer winding.
There are following advantages and disadvantages of both types of Transformers:-
Oil Type Transformers Advantages:-
(a) Oil type Transformers are more efficient than Dry type Transformers
(b) Oil Type Transformers have usually higher life than dry type transformers
(c) In Oil type Transformers, Oil is better medium for cooling than air and thus reduces the hot spot in winding.
(d) Oil type Transformers overload capability than dry type transformers.
(e) For same rating Oil type Transformers have lower cost than dry type transformers
(f) Oil Type transformers have lower losses than dry type Transformers. In Oil type Transformers power losses are half than power losses in Dry Type transformers.
(g) Oil Type Transformers have lower sizes than Dry Type Transformers for same rating at same voltage.
Dry type Transformers Advantages:-
1. As Oil Type Transformers have Oil as cooling medium, Oil can catch fire in case of fault in Transformers but dry type Transformers can’t catch fire. Thus for Oil and gas/ Hazardous industries Dry type transformers are used.
2. Oil type Transformers require more maintenance as Oil can contaminate which needed to be filtered at regular intervals but same is not required in Dry type Transformers.
3. In Oil type transformers more protection required against leakage of oil same isn’t required in dry type transformers.
4. Dry type transformers can be more closely installed near load in comparison to oil type due to safety concerns. This will leads to reduction in Transmission losses.
For outdoor applications in Non-hazardous areas Oil Type Transformers are used but for Indoor applications/ hazardous areas dry type transformers are used.