Dry Type Transformers vs. Oil-Filled Transformers


Transformers are necessary equipment for running small electric appliances. Directly connecting the application with an electric pylon can lead to an explosion. Transformers convert high voltage power into low voltage electric current so that devices can use it. Whether it is dry type transformers or oil-filled transformers, both enable power conversion to be safely used by offices, homes, and even small industries.

However, both the transformers perform the same function. They have significant differences when it comes to structure and operation. There are different types of dry type transformers as well that assist the electric conversion for domestic usage.

This article will highlight the differences between dry type transformers and oil-filled transformers on several bases. So if you’re looking to install a transformer, you can make the right decision.

Difference Between Dry type transformers vs. Oil-filled transformers

The following points of difference will give a clear view of both the types of transformers and how they operate.

Cooling medium

The most significant difference in both the transformers is that Dry type transformers use air as a cooling medium. On the other hand, Oil-filled transformers use oil as a cooling medium. Different types of dry type transformers are used at most public places as the oil-filled ones are susceptible to catch fire. That’s why they are used mostly in outdoor settings where even if there’s a leak, it doesn’t lead to a significant hazard. However, you will see dry types used more frequently and can find them in transportation hubs and office buildings.


On the contrary to a cooling medium, oil-filled transformers are inexpensive than dry type ones. This is because they operate on standard energy efficiency, making them reliable and giving a long lifespan. Dry transformers have a significantly high operating loss, so they use more energy, leading to extra operation costs. However, the initial cost isn’t that much of a difference.


In terms of maintenance, the dry type transformers triumph over oil-filled ones. They do not require heavy maintenance and work seamlessly for a long time. Oil-filled transformers need more attention as the oil needs to be frequently tested for chemical contamination. Dry transformers do not need to be taken off the grid if a minor incident occurs. However, oil-filled are riskier as they can lead to a potential hazard even if a small accident occurs.


Oil-filled transformers operate smoothly and thus make negligible noise. However, dry type transformers make more noise as they use air which rotates inside the machine. Therefore, they lead to higher noise pollution than their counterparts. They are noisier and irritate anyone who comes near them.

Energy efficiency

One of the most significant points of difference is in energy efficiency. Dry type transformers lead to higher energy loss because they are large in size and limited in voltage. Also, they get overheated when there is overloading, making them less energy efficient. Oil-filled transformers are small and create a lower environmental footprint, leading to less energy consumption. They are ultimately much more energy-efficient than dry ones.

Installation site

Another major aspect is the installation site. Dry type transformers are explicitly used in buildings because they are less riskier and more environmentally safer. They are also less flammable, and that’s why used in shopping malls, corporate offices, and more. Oil-filled transformers are mostly installed in outdoor locations due to the possibility of an oil leak that could lead to a significant hazard. However, they are more environmentally friendly than dry ones.

Considering the above factors, oil-filled transformers appear to be a better option. However, the decision ultimately depends on where you want to install it and how much risk you are willing to take. For indoor operations, however, dry type transformers are the best choice.