Dry Type

Dry type transformer

Dry-type transformers are a type of transformer that uses air to insulate its windings, rather than insulating liquid. This makes them more environmentally friendly and safer to use than liquid-filled transformers. Dry-type transformers are also more efficient, with lower losses and less maintenance required.

There are four main types of dry-type transformers:

Vacuum Pressure Impregnated (VPI) Transformers use a vacuum pressure impregnation technique. They are made of high-temperature materials that are coated with moisture-resistant, and polyester sealants.

Vacuum Pressure Encapsulated (VPE) Transformers are similar to VPI transformers, however, a resin made of silicone is used instead of a polyester sealant. Numerous dip methods are used to make these transformers, which are then baked to cure the coating. In addition, the resin covering on these transformers is up to four times thicker than on VPI transformers.

Open Wound Transformers use a dip-and-bake method whereby conductor coils are pre-heated, heated, and then dipped in a heated varnish at an elevated temperature. After that, the coils are baked to cure the varnish.

Cast Resin Dry-Type Transformers are used in the most extreme environments, such as in wet or corrosive areas, as they are completely sealed and have a very high resistance to moisture and corrosion. They are available in ratings of 25KVA to 12,500 KVA.