This article will discover the benefits and applications of dry type distribution transformers. Learn how these efficient, safe, and eco-friendly transformers are transforming power distribution for various industries. 

 

Introduction 

 

In the realm of power distribution, efficiency, safety, and environmental impact are critical considerations. Dry type distribution transformers are gaining popularity as a reliable solution that addresses these concerns effectively. Unlike traditional oil filled transformers, dry type transformers use air or other environmentally safe materials for cooling, making them an ideal choice for a variety of applications. In this post, we will explore what dry-type distribution transformers are, their advantages, and why they are becoming the preferred choice for modern electrical systems.

 

1. What is dry type transformers? 

A dry type transformer is a type of transformer that changes the voltage of an electric current and can operate in harsh environments with high temperature and humidity. Unlike conventional transformers, this product does not use insulating liquid inside where the coil and electromagnetic circuit are located. The coils and magnetic core are pressurized by air.

The dry transformer has no moving parts, it is a static electrical device that uses an environmentally friendly insulation system. Dry transformers have a cooling system through natural ventilation as opposed to using oil, silicon, or liquid to cool the windings and core like oil filled transformers.

Unlike oil transformers, dry transformers can be placed indoors, in harsh, high humidity environment, which prevents toxic gases omitting or oil spilling out. This helps the entire electrical system operates more smoothly and efficiently. For these reasons, dry  type transformers are installed in many places, such as schools, apartment buildings, hospitals, shopping centers, factories, chemical industry, and metallurgy, oil and gas, and more, where there are special fire safety requirements.

Dry transformers have several advantages over oil transformers, including:

1. Safety: Dry type transformers do not use coolant reduces the risk of fires and oil leaks, especially in urban environments and places with high safety requirements.

2. Maintenance: Unlike oil-filled transformers, dry type transformers do not require periodic inspection and oil changes. Thus, this reduces maintenance costs and time.

3. Environmental impact: Since dry type transformers do not use oil, this minimizes the risks of environmental pollution that is caused by oil leakage. 

However, dry transformers also have some disadvantages, such as poorer heat transfer efficiency and larger size compared to oil transformers at the same power level.

Structure of the dry type transformers

A dry type transformer is composed of three main parts: Steel core, windings and transformer shell.

  • Steel core

The steel core of a dry transformer is made from materials that are good magnetic conductors and have high oxidation resistance, usually electrical engineering steel sheets such as silicon corrugated iron. The function of the steel core is to conduct magnetic flux and serve as a frame for placing the winding wire. The steel core consists of many thin steel sheets with insulating paint on the outside with a thickness of 0.3 to 0.5mm that are joined together to form a closed circuit. The purpose of joining thin steel sheets together is to reduce energy loss that occurs during machine operation due to eddy currents.

The steel core consists of two main components: the pillar and the yoke. The post is the place to place the winding wire. The bridge is the connection between the pillars to form a closed magnetic circuit.

  • Windings

The winding of a dry transformer is often used with pure copper wire, has a circular cross-section and the outside is insulated to help conduct electricity better, avoid oxidation, and increase the life of the transformer. The winding's function is to receive energy in and transmit energy out.

The winding of a dry transformer must ensure technical indicators such as flexibility, adhesion, electrical strength, elongation, elasticity, and transformer oil resistance to help reduce Foucault eddy currents that occur during operation. 

  • Transformer shells

The shell of a dry transformer is usually made from steel. It is designed depending on the type of machine to protect the internal elements of the machine, and its tank does not contain oil like an oil transformer.

 

2. Types of dry transformers

The two main dry transformers are: 

  • CRT: Cast Resin Dry Type Transformer
  • VPI: Vacuum Pressure Impregnated Transformers
  • CRT: Cast Resin Dry Type Transformer

Dry resin transformers (CRTs) are used in areas with high humidity. This is because its primary and secondary windings are coated with epoxy resin. This coating helps prevent moisture from penetrating to affect the coil material and provides very good insulation. This helps the machine operate smoothly and effectively. This type of transformer is available in the market with capacities from 25KVA to 12,500KVA, with insulation class of F (90oC Temp. Rise).

 

VPI: Vacuum Pressure Impregnated Transformers

This type of transformer has coils made from insulating materials that are difficult to burn. The machine's coil is designed in the form of a disc, in series or also in parallel for higher voltages, depending on the appropriate power level corresponding to the voltage level.

The insulating part of the coil is made from H-grade polyester resin to prevent contamination. As for the vacuum box, the function is to protect the primary, secondary and core coils from moisture contamination and prevent the phenomenon of being affected by moisture from occurring. The capacity of this type is only from 5KVA to 30KVA, while the protection level is up to PI 56.

This type of vacuum pressure transformer has the following outstanding advantages:

  • The machine has high mechanical durability. 
  • No restrictions in insulation. 
  • No fluctuations in temperature occur. 
  • Safe, low risks of conflagration. 
  • Convenient design for maintenance. 

 

Applications of Dry Transformers

Dry transformers are used widely in many industries. Specifically, there are prominent industries that uses dry transformers, including: 

  • Chemical industry, metallurgy, petroleum industry
  • High humidity environmental areas such as swamps and water source protection areas
  • Areas with high risk of fire such as mountains and forests
  • Transformer stations in the city
  • Underground and indoor transformer stations
  • Renewable energy sources such as offshore wind turbines.

Dry-type distribution transformers represent a significant advancement in the field of power distribution. Their inherent safety, environmental friendliness, and robust performance make them an ideal choice for various applications, from commercial buildings to industrial complexes. As the demand for energy-efficient and sustainable solutions continues to grow, dry-type transformers are poised to play a pivotal role in the future of electrical systems. By choosing dry-type distribution transformers, industries can ensure reliable power delivery while also contributing to a greener and safer environment.