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What are Dry-type Transformers

dry-type transformers

A transformer is an electrical device that transfers or controls electricity. It is a fully solid static device. It does not have any moving elements attached to it. It is of various types but generally, the dry-type transformers also known as cast resin type of transformer are recommended for their various advantages. Firstly, it is efficient, economical, and safe in many ways. It functions in high temperatures. It does not require fire protection, does not emit toxic gasses.

It can be used both indoors and outdoor. Outdoor is used for utility or commercial and industrial purposes. Thus, they are consistent and secure in power supply either in school, hospital, factory and so on. In other words, where there is a large amount of electricity consumption is required on daily basis.

Another significant point is it does not use anything to cool its core and coil. It is built as an isolation device that is cooled down by air. Its case is designed in a way that allows air to supply and cools its coils.

Different Types of Dry-type Transformers

They are different models of dry-type electrical transformers like Open Wound Transformer (OWT), Vacuum Pressure Impregnated (VPI), Vacuum Pressure Encapsulated (VPE), and Cast Coil dry type transformer. Each dry-type power transformer is meant for a different purpose and designed in such a manner.

Open Wound Transformer (OWT) – is named according to its function. For example, it is used to dip and bake the coils. Initially, coils are heated and dished in paint and baked.

Vacuum Pressure Impregnated (VPI) – These transformers are protected from high temperatures. They are designed from materials that protect them from high temperatures. They’re generally sealed with polyester especially that resists moisture and uses vacuum pressure impregnation as a strategy. This type of Dry Transformer is generally used for commercial and industrial purposes.

Vacuum Pressure Encapsulated (VPE) – Its material is scientific-based resin. It generates thick paint which resists extreme humidity. In other words, it is meant for usage in extreme environments.

Cast Coil (CC) Dry-type power transformer – It is manufactured to use in harshest weather conditions but it does not require much maintenance. It saves from high short circuits. It is majorly used in the mining industry, cranes, nuclear plants, ships, and tunnels.

Where Dry Type Transformer is used?

Dry-type transformers are used in different types of industries like oil, gas, and chemical. They are also used in water plant areas that are sensitive to the environment. Further, they are also used in forests, substation areas like inner cities, indoors, and underground as well.

There are various factors to be kept in mind while designing these dry-type transformers. Like type as well as the level of insulation, its life span or longevity, winding, and core material selection, overloading, losses, K-factor, and regulation.


There are various advantages of dry-type power transformer like it is environment friendly, can be used in damp and contaminated places, lasts long, safeguards life and property, simple and easy to install, resistant to short circuit, excels in performance, can support overloads and so on.


Everything has its advantages as well as disadvantages similar is the case with it. As it is environmentally friendly and protects lives and so on.

Thus, it is expensive. It is difficult to maintain, if its coils are not cleaned in time and properly then it may cause a fire. It needs downtime.

Its electrical loss will be huge. It creates sound pollution so not indoor friendly. It requires a cooling system to control the losses generated by heat.

Also read:

Right Choice of Dry Type or Liquid-Filled Transformer

To conclude, Dry-type transformers has various advantages like it is not very expensive and easy to manage. Its cost of installation is also very low.

A dry-type electrical transformer helps in transferring and controlling electricity. It is of various types but the dry type of power transformer is used for its many advantages.

Like it is easy to manage, fits into budget easily, performs better in high temperature and so on and so forth. More importantly, it can be used indoor and outdoor as well. It is consistent in power supply.