Distribution Transformer: What Is It Used For?

24 April 2023

A distribution transformer is a type of transformer that is used to reduce electric energy from high voltage to low voltage. It possesses a transforming capability among transformers.

When voltage is applied to the primary winding, or the first coil, of transformers, a magnetic flux is generated within the coils. This magnetic flux begins to circulate. Distribution transformers, in turn, convert this circulating flux.

Types of Distribution Transformers

Distribution transformers come in various specifications depending on the intended use. These transformers have three different power levels, ranging from 25 kVA to 2500 kVA.

Types of distribution transformers include:

  1. Hermetic Type
  2. Expansion Tank Type
  3. Dry Type

Hermetic Type Distribution Transformers

Usually, these transformers have a voltage range of 1 to 36 kV. They are available in both 3-phase and 1-phase options and have ONAN and ONAF cooling systems.

Since they are designed in a sealed atmosphere, they prevent the insulation oil from coming into contact with oxygen. This prevents oxidation and insulation degradation that may result from oxidation.

Expansion Tank Type Distribution Transformers

Expansion tank distribution transformers are available for all voltage levels from 1 to 36 kV. They are designed to be open to the atmosphere and do not require pressure adjustments.

They come equipped with moisture-absorbing devices capable of absorbing humidity in case the air gets moist. These devices can be replaced when they absorb moisture.

They do not cause problems related to excessive high pressure or harmful pressure. Moreover, they offer the advantage of on-site maintenance and repair.

Dry Type Transformers

Dry type transformers can be safely used in locations where there is no risk of explosion. They are fire-resistant and are often used in places such as:

  • Hospitals
  • Hotels
  • Shopping centers
  • Dams and railways
  • Corporate buildings
  • Schools

They have a magnetic circuit with windings immersed in non-insulating liquid. Their winding structures are resistant to short circuits.

Materials Used in the Production of Distribution Transformers

Materials used in the production of distribution transformers vary depending on the cooling type. Common materials used in the production of these transformers include:

  • Main tanks containing windings and magnetic cores
  • Voltage stage commutator
  • Magnetic iron core
  • Primary and secondary windings
  • Arc horn that prevents damage to the insulation material

These materials ensure the healthy progression of the transformer’s working principle, which can vary depending on the type and specifications of the transformer.