Dry-Type Transformer – All You Need To Know

What is a dry type transformer?

A type of transformer which is a power transformer with windings encased in the epoxy resin called a dry-type transformer. This dry type power transformer makes the installation process easier as it is dry and does need a cooling oil process. The transformer is used to increase or decrease voltages and currents in an electrical circuit. The dry-type transformer is highly recommended as it is more economical, packs important safety features, and more efficient than other types of transformers.

Two different types of dry-type transformers:

There are two types of dry type transformer, included:

  1. Cast resin dry type transformer (CRT)
  2. Vacuum pressure impregnated transformer (VPI)

Cast resin dry type transformer (CRT):

This type of dry-type transformer is usually used in high moisture-prone areas. As primary and secondary windings of cast resin dry-type transformer are encapsulated with epoxy resin. The encapsulation of this transformer helps to prevent moisture to penetrate to affect the material of windings. Cast resin encapsulation achieves complete protection so the transformer can easily work without interruption in high moisture-prone areas. This type of dry-type transformer is non-hygroscopic.

Advantages:

  • Low partition discharge along with low loss, therefore, efficiency is very good.
  • Good overload capacity.
  • It is zero risks to fire hazard as it is with non-inflammable winding insulation. It is very suitable for indoor installation.
  • It can be fitted outside also in IP 45 enclosure.
  • Non-hygroscopic.

Vacuum pressure impregnated transformer (VPI)

This type is made with minimum flammable materials as windings insulation. The transformer windings are made in foil or strips in a continuous layer. The winding is made of disks for the higher voltage that is connected in series or parallel as per the power rating of winding to the level of voltage. The windings insulation is void-free impregnation that is made with H class polyester resin. Within a vacuum protective box, the primary and secondary winding with the core is laced safely.

Advantages:

  • Void free insulation.
  • No temperature fluctuation.
  • High mechanical strength.
  • Less prone to fire hazards.
  • Easy maintenance.