What Are Dry-Type Transformers and What Makes Them Better?

What Are Dry-Type Transformers and What Makes Them Better?

Dry-type transformers, also known as cast resin transformers, are power transformers with windings encased in epoxy resin. This makes the installation process easier because they are dry and do not require cooling oil. Plus, they do not need to be contained in a fire-proof vault. The layer of epoxy helps protect it against dust and corrosion. Dry-type transformers are used in a wide variety of applications and can be installed indoors or outdoors.

Transformers are used to increase or decrease voltages and currents in an electrical circuit. There are a variety of transformers out there, including liquid-type transformers, but there are plenty of good reasons why we recommend dry-type transformers. They are more economical, they pack important safety features, and they are more efficient.

Dry-type transformers are commonly used for industrial, utility and commercial applications. All our transformers are weather protected with NEMA 3R outdoor enclosures. Plus, they are outdoor rated and mounted to a skid frame. But those aren’t the only reasons dry-type transformers rule supreme. Read on to learn more!

What are Dry-Type Transformers?

A dry-type transformer has no moving parts, it is a static device that uses environmentally friendly temperature insulation systems. Traditional liquid-type transformers rely on environmentally taxing materials like oil or fire resistant liquid dielectric. “Dry” refers to the fact the system is cooled through natural ventilation as opposed to using oil, silicone or a liquid to cool coils and the electrical core. This type of transformer is defined as “voltage changing,” which means air is cooled instead of cooling liquid. The case the transformer sits inside is ventilated so air can cool coils.

Unlike liquid transformers, dry-type transformers do not need to be placed inside of fire proof vaults or catch basins, and you don’t have to worry about venting toxic gases out. Since dry-type transformers are much safer, they can be placed indoors and closer to loads, which makes the entire system more efficient.

Types of Dry Transformers

There are variations of dry-type transformers. Different environments and applications call for slightly different models. For instance, VPI dry-type transformers are recommended for those looking for radiance protection and advanced mechanical power. On the other hand, a cast coil transformer is recommended for harsher environments.

  • Open Wound Transformer

This type of transformer gets its name through its manufacturing process, which involves the “dip-and-bake” method. The coils are heated, dipped in high-temp varnish and then baked, a process known as the open wound method.

  • Vacuum Pressure Impregnated (VPI)

VPI transformers are commonly used for commercial and industrial purposes. They have a high-temperature insulation that ranks over ‘O’ and ‘K’ fluid classifications. VPI transformers are made from materials that can withstand high temperatures and moisture-resistant polyester sealant that is typically applied with a vacuum pressure impregnation technique. For the most part, they are rated up to 30 MVA.

  • Vacuum Pressure Encapsulated (VPE)

VPE transformers are comparable to VPI described above. Yet, instead of polyester they are made from a silicon-based resin, this creates a thicker coating that is highly resistant to moisture, salt and high humidity, making it an excellent choice for harsher environments. They are used in environments that are susceptible to acids, chlorides and alkalis. 

  • Cast Coil

Cast coil transformers are reliable even in extreme weather and require very little upkeep. They are commonly found inside of tunnels or buildings, onboard ships, offshore platforms, as well as at nuclear plants, mining facilities, and production plants.

Rent or Buy Dry-Type Transformers

Cooling Power offers a variety of dry-type transformers available for rent or sale. Learn more by visiting https://coolingpowercorp.com/our-services/power-services/transformers/