Comprehensive technical analysis of dry-type transformers: Why is it accelerating the replacement of oil immersed transformers in the wave of new energy and data centers?

With the rapid development of new energy, electric vehicles, data centers, and urban power distribution systems, Dry Type Transformers are experiencing a new round of growth worldwide.
Compared with traditional oil immersed transformers, dry-type transformers have obvious advantages in safety, environmental protection, and maintenance costs, especially in high fire protection requirements, densely populated or indoor installation scenarios, and are accelerating the replacement of oil immersed solutions.

This article will systematically analyze the technical value and market logic of dry-type transformer from five dimensions: structural principles, core technologies, application scenarios, international standards, and future trends.

1.Basic principles and structure of dry-type transformers

1.1 Working principle of dry-type transformers

Dry-type transformers essentially still follow the principle of electromagnetic induction, completing voltage conversion through magnetic flux coupling between the primary and secondary windings.
The biggest difference from oil immersed transformers is that:

Not using insulating oil as a cooling and insulating medium
Mainly relying on air convection or forced air cooling for heat dissipation
This has led to fundamental changes in its structure and operational characteristics.

1.2 Main structural components

Dry-type transformers typically consist of the following core components:

iron core

• Stacking of cold-rolled silicon steel sheets
• Low loss, high magnetic permeability design

winding

• High voltage winding: mostly made of copper or aluminum conductors
• Low voltage winding: foil winding or wire winding structure

Insulation system

• Epoxy resin casting
• Insulation paper+glass fiber composite

cooling system

• AN (natural air cooling)
• AF (forced air cooling)

2.The mainstream technical route of dry-type transformers

2.1 Epoxy resin cast dry-type transformers

This is currently the most widely used and technologically mature type, characterized by:

• The winding is cast as a whole, with strong short-circuit resistance
• Excellent moisture and dust resistance
• Suitable for harsh environments

But at the same time, there are also:

• Relatively high cost
• Difficulty in maintenance

2.2 Non encapsulated (VPI) dry-type transformers

The dry-type transformers with VPI (Vacuum Pressure Impregnation) vacuum pressure impregnation process has seen a significant increase in demand in overseas markets in recent years.

Key Features:

• Better heat dissipation performance
• Low operating noise
• Suitable for high-capacity and continuous load conditions

2.3 High temperature insulated dry-type transformers

With the development of new material technology, H-class and C-class insulation systems are gradually being applied to dry-type transformers:

• Allow for higher operating temperatures
• Enhance power density
• Suitable for the fields of new energy and rail transit

3.Dry-type transformers vs oil immersed transformers

3.1 Safety Comparison

Item	Dry Type Transformer	Oil-Filled Transformer
Fire risk	Very low	Higher
Oil leakage	None	Possible
Indoor installation	Highly suitable	Restricted

3.2 Operations and Life Cycle Costs

Although the initial procurement cost of dry-type transformer is higher than that of oil immersed transformers, throughout their entire lifecycle:

• No need to change the oil
• Low frequency of operation and maintenance
• Low shutdown risk

TCO (Total Cost of Ownership) is actually lower.

4.Core application scenarios of dry-type transformers

4.1 New Energy System

• Photovoltaic power station box transformer
• Wind power grid connected system
• Energy storage converter system

4.2 Data Center and Communication Base Station

Data centers have extremely high requirements for fire prevention, stability, and low noise, and dry-type transformers have almost become standard.

4.3 Urban Public Buildings

• hospital
• subway
• commercial complex
• High rise office building

5.International Standards and Export Focus

Common international standards for dry-type transformers include:

• IEC 60076-11
• IEEE C57.12
• EN 50541

When exporting, special attention should be paid to:

• insulation class
• noise level
• Partial discharge level
• Protection level (IP)

6.Future Trends and Technological Development Directions

6.1 High energy efficiency and low loss

The tightening of energy efficiency regulations in various countries is promoting the development of dry-type transformers towards lower no-load losses.

6.2 Digitization and Intelligent Monitoring

• Temperature online monitoring
• Partial discharge online detection
• Remote operation and maintenance system

6.3 New Materials and Lightweight Design

• New composite insulation materials
• Higher permeability iron core

Against the backdrop of the global power system evolving towards safety, greenness, and digitization, dry-type transformers are no longer just an “alternative solution”, but are becoming the mainstream choice.
For manufacturers and exporters, whoever can lead in technology, standards, and application understanding will have an advantage in the global market.

Luoyang Datang Energy Technology Co., Ltd. is a high-tech enterprise integrating R&D, manufacturing and supply of power equipment such as transformers, new energy components, distribution cabinets and inverters. With technological innovation as the core, we focus on creating high-reliability and high-performance power solutions to serve global customers. With a strict quality control system and international standard certification, we continue to output excellent products and enable customers to build safe and stable power systems.