Dry Type Transformers: Structure, Advantages & Applications

Why are dry type transformers accelerating the replacement of oil immersed transformers?

Against the backdrop of global energy transition, upgrading of urban power grids, and continuous improvement of building safety standards, Dry Type Transformers are increasingly being applied in commercial buildings, data centers, rail transit, new energy projects, and industrial scenarios.
Compared to traditional oil immersed transformers, dry-type transformers have significant advantages in fire safety, environmental performance, and maintenance costs, and have become an important development direction in the field of medium and low voltage distribution.

1.Basic working principle of dry type transformers

1.1 What is a dry type transformers?

Dry type transformers is a power transformer whose windings are not immersed in insulating oil and mainly rely on air or solid insulation materials for insulation and heat dissipation.

Common types include:

Epoxy resin cast dry-type transformers
Non encapsulated (VPI vacuum pressure impregnation) dry-type transformer

1.2 Brief description of working principle

Dry type transformers are based on the principle of electromagnetic induction:

Primary winding energized → generates alternating magnetic flux
Magnetic flux passes through the iron core and induces voltage in the secondary winding
Realize voltage level conversion and power transmission

2.Analysis of the core structure of dry type transformers

2.1 Iron Core System

Adopting high magnetic conductivity and low loss cold-rolled oriented silicon steel sheets

45 ° or stepped laminated structure to reduce no-load losses and noise

2.2 Winding System

Item	Copper Winding	Aluminum Winding
Conductivity	Excellent	Good
Cost	Higher	Lower
Thermal Stability	Very High	Moderate
Typical Use	Premium projects	Cost-sensitive projects

2.3 Insulation and heat dissipation system

Epoxy resin casting → high mechanical strength, moisture resistance, and pollution prevention
Natural air cooling (AN) or forced air cooling (AF)

3.Main technical parameters of dry type transformers

Parameter	Typical Range
Rated Capacity	50 kVA – 2500 kVA
Voltage Level	Up to 35 kV
Insulation Class	F / H
Temperature Rise	100K / 125K
Protection Degree	IP00 – IP54

4.Core advantages of dry type transformers

4.1 Security advantages

No insulation oil → zero fuel risk

Compliant with fire prevention regulations for high-rise buildings, hospitals, and subways

4.2 Environmental advantages

No risk of oil leakage

Compliant with RoHS/REACH/IEC standards

4.3 Low operation and maintenance costs

No need to change or filter the oil

Suitable for long-term continuous operation

5.Typical application scenarios of dry type transformers

Commercial Complex&Office Building

Data Center&Communication Room

Photovoltaic/energy storage/wind power system

Hospitals, airports, and rail transit

High end industrial plant

6.Comparison between dry type transformers and oil immersed transformer

Item	Dry Type Transformer	Oil-Immersed Transformer
Fire Safety	Very High	Medium
Environmental Risk	Very Low	Higher
Installation	Indoor preferred	Outdoor preferred
Maintenance	Simple	More complex
Initial Cost	Higher	Lower

7.Development trend of dry type transformers industry in 2026

7.1 New energy drives demand growth

Photovoltaic and energy storage systems have high requirements for fire prevention and low maintenance

7.2 High energy efficiency standards promote upgrading

IEC 60076-11

EU EcoDesign requirements

7.3 Intelligence and Digital Monitoring

Temperature online monitoring

IoT+SCADA integration

8.Selection Suggestions (Practical Guide for Engineering Procurement)

Indoor&personnel intensive → Epoxy casting type

High temperature and high humidity environment → H-grade insulation

High load operation → Optional AF forced air cooling

Dry type transformers are upgrading from a “safe alternative solution” to a “mainstream distribution equipment”. For export-oriented manufacturers and engineering contractors, a deep understanding of their technical characteristics and application trends will directly affect project competitiveness and winning probability.

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.