A dry-type transformer is a type of transformer that never utilizes any insulating liquid with liquid immersion and winding. The windings and core are kept within a sealed tank with air pressure.

The cast resin dry-type transformer is utilized in high moisture-prone areas. It is led by encapsulated usage of the primary and secondary resins with winding material. The cast resin encapsulation provides complete protection to the transformer to ensure that it functions without disruption in a highly moisture-prone area. 

Therefore, this transformer is non-hygroscopic. It is a transformer made available in ratings of 25 KVA to 12,500 KVA with an insulation class of 90 C Temp. 

Featured Advantages of this type of transformer: 

•    They offer better overload capacity
•    They provide low partial discharge with low loss and hence provide good efficiency.
•    It is non-inflammable winding insulation that offers zero risk to fire hazards. That is why it suits indoor installation. 
•    It can be fitted outdoors in IP 45 enclosure. 

 Vacuum Pressure Impregnated Transformer (VPI) 

This transformer is made with minimum flammable material as windings insulation. The transformer windings are made in strips or foil in a continuous layer. The winding is developed from disks, that are connected in parallel or series according to power rating concerning the voltage level. 

The winding insulation is void-free impregnation developed with class H polyester resin. The primary and secondary core winding is laced safely within a vacuum protective box. The moisture ingress protection does not let it get affected by the moisture. 

This transformer ranges from 5KVA to 30MVA with insulation grade H (180oC) and F(155oC). 

This transformer comes with numerous advantages such as; high mechanical strength, no temperature fluctuation, void-free insulation, less prone to fire hazards, and easy maintenance. 

Vacuum Pressure Encapsulated Transformer (VPE) 

This transformer is made up of Si-based resin instead of polyester. Such transformers generate extremely thick varnish that is extensively resistant to humidity, salt, and others. These are utilized for harsher environments application. 

Cast Coil Transformer 

Cast coil transformers are consistent in extreme weather conditions, and hence they require very less maintenance. They can also resist high short circuits. That is why they were used at an earlier time when liquid-filled units were available for harsh temperatures. Presently, these are massively used in tunnels, ships, cranes, nuclear plants, and mining industries. 

Open Wound Transformer

An open wound transfer utilized the dip and bake method. It involves heating the coils at first instance, then it is dipped in varnish, and the last step involves baking them. 

Dry Type Transformer Application

Dry-type transformers are widely used in fire-risk areas, chemical, gas, and oil industry, inner-city substations, fire-risk areas, renewable generation, and indoor and underground substations. 

The major players operating in the industry are; Siemens AG, Schneider Electric, General Electric, Tbea Transformer Industrial Group, Hammond Power Solutions, and Voltamp Transformers. 

Therefore, the higher efficiency of dry-type transformers leads to their increased adoption.