Distribution Transformers and Their Types

9 May 2023

A distribution transformer, also known as a distribution transformer, is an electrical device that reduces high voltage to low voltage for the distribution of electrical energy. When an alternating current is applied to the primary winding of the transformer, the magnetic core inside the coils generates a magnetic flux, and this flux starts to circulate, facilitating distribution. There are three main types of distribution transformers: expansion tank type, dry-type, and hermetic type.

Hermetic Type Distribution Transformers

Hermetic type distribution transformers are oil-filled, air-insulated transformers produced in standard types up to 36 kV. One of the most significant features of these transformers is the prevention of contact between the insulating oil and the air. This prevents issues caused by the isolation oil coming into contact with the air. This type of transformer, due to the absence of an oil expansion tank, is advantageous in terms of requiring less space. Additionally, its hermetic design prevents oxygen from coming into contact with the insulating oil, eliminating issues related to oxidation.

Expansion Tank Type Distribution Transformers

Expansion tank type distribution transformers come in single-phase or three-phase options, with conductor types typically being aluminum or copper. They are designed to be exposed to the atmosphere. These transformers do not require any pressurization; adjusting the levels of insulating oil is sufficient. The absence of harmful pressure inside the transformer prevents pressure-related issues during overload conditions. Furthermore, there is less deformation in the metal due to factors such as expansion. They are easy to maintain and repair.

Dry-Type Transformers

Dry-type transformers are commonly used in residential buildings, commercial properties, or shopping centers. One of their most important features is their non-explosive nature. Although they are more expensive compared to oil-filled transformers, they are preferred due to the absence of explosion risks. They are commonly used in densely populated buildings where people are present. Dry-type transformers have high electrical insulation properties, thanks to their high-resistance epoxy casting resin covering the high-voltage winding. Unlike other transformers, their cooling can be achieved by natural air circulation. They are advantageous for their ability to be cooled both by natural air circulation and by fans.