A dry-type transformer is a type of electrical transformer that uses air or solid insulation to isolate the winding conductors from the environment, as opposed to a liquid-filled transformer which uses oil or other liquid as an insulating medium. Dry-type transformers are commonly used in indoor applications where liquid-filled transformers may not be suitable due to safety or environmental concerns, such as in commercial buildings, industrial facilities, and data centers.
There are several types of dry-type transformers, including:
Cast Resin Transformers: These transformers use epoxy resin as an insulating medium, which is poured into the transformer core and windings, and then cured to form a solid insulation. Cast resin transformers are known for their excellent fire resistance, moisture resistance, and environmental friendliness, as they do not contain any oil or other hazardous substances.
VPI (Vacuum Pressure Impregnation) Transformers: In VPI transformers, the windings are vacuum impregnated with epoxy resin to ensure proper insulation. The resin is then cured under pressure to form a solid insulation. VPI transformers are known for their high reliability, low partial discharge levels, and good mechanical strength.
Encapsulated Transformers: These transformers have their windings and core encapsulated in a solid epoxy resin, forming a single compact unit. Encapsulated transformers are highly resistant to moisture, dust, and chemicals, making them suitable for harsh environments.
Air-Core Dry-Type Transformers: These transformers use air as the insulating medium between the windings and the core. Air-core transformers are used in applications where high insulation levels are not required, and they are typically smaller and lighter than other types of dry-type transformers. However, they may have lower efficiency and are less common in commercial and industrial applications.
