Dry-type transformers play a vital role in modern power distribution systems. Unlike oil-immersed transformers, they use air or resin for insulation and cooling, making them safer, more environmentally friendly, and easier to maintain. Selecting the right dry-type transformer model is essential to ensure reliable performance, cost-efficiency, and long service life. This article introduces the most common dry-type transformer models and their application scenarios to help you make an informed decision.
What Is a Dry-Type Transformer?
A dry-type transformer is a power transformer that uses air or solid insulation (such as epoxy resin) instead of insulating oil. It is designed to operate safely in environments where fire risk, pollution control, and maintenance convenience are critical. These transformers are widely used in commercial buildings, hospitals, data centers, tunnels, offshore platforms, and industrial facilities.
Classification of Dry-Type Transformer Models
Depending on their structure, insulation material, and cooling method, dry-type transformers are commonly divided into several models. The three most widely used models are:
SG Dry-Type Transformer (Silicon Steel Lamination, Open Type)
The SG series dry-type transformer features an open winding design with natural air cooling. It uses silicon steel lamination for the core and is often applied in control circuits or auxiliary power systems. While it's relatively cost-effective, it requires a clean and dry environment for optimal performance.
SCB Series Epoxy Resin Cast Transformer
The SCB series is a fully encapsulated transformer where the high-voltage windings are cast in epoxy resin. This model has excellent moisture resistance, flame retardancy, and mechanical strength. SCB transformers are ideal for environments with high humidity or heavy dust, such as metro stations, mines, and chemical plants.
SC Series Resin-Impregnated Dry Transformer
Unlike the SCB model, the SC transformer uses resin-impregnated windings rather than full casting. This design improves heat dissipation while maintaining good insulation performance. It’s widely used in indoor substations and industrial plants requiring high reliability and moderate environmental resistance.
Key Parameters to Consider in Model Selection
When selecting a dry-type transformer model, it's essential to evaluate the following technical parameters and operating conditions:
Rated Capacity (kVA)
This indicates the maximum load the transformer can handle. Oversized units lead to energy waste, while undersized ones may overheat and fail. The rated capacity should match your total equipment load, with a reasonable margin.
Primary and Secondary Voltage
Ensure that the input and output voltage levels of the transformer align with your grid and equipment requirements. Standard voltage combinations include 10kV/0.4kV, 6kV/0.4kV, and others.
Insulation Class
Dry-type transformers are commonly available in insulation classes F and H. Class F supports up to 155°C, while Class H supports up to 180°C. Choose a higher class for high-temperature environments.
Cooling Method
The most common cooling methods include natural air cooling (AN) and forced air cooling (AF). SCB and SC series may support both, while SG models typically use natural cooling only.
Noise Level and EMC
Low-noise operation is vital in hospitals, schools, and residential areas. For sensitive electronic environments, choose models with good electromagnetic compatibility (EMC).
Application Scenarios of Common Dry-Type Transformer Models
Different transformer models are better suited for specific environments and use cases. Here’s how they compare:
SG Series - For Clean Indoor Environments
SG dry-type transformers are best used in low-dust, well-ventilated indoor environments, such as workshops, mechanical control panels, and laboratories. They are simple in design, easy to maintain, and relatively low in cost. However, they are not suitable for harsh or outdoor environments due to their open structure.
SCB Series - For High-Safety and High-Moisture Environments
SCB transformers are ideal for metro stations, tunnels, hospitals, high-rise buildings, and coastal or humid areas. The epoxy resin encapsulation offers strong insulation and flame-retardant properties. This model also meets stringent fire safety and environmental regulations.
SC Series - For Industrial and Utility Applications
SC transformers strike a balance between performance and cost. They are suitable for industrial factories, data centers, and power stations that require moderate dust resistance, good thermal stability, and high load-bearing capacity.
Emerging Trends in Dry-Type Transformer Design
With the advancement of smart grid technology and energy efficiency standards, dry-type transformers are evolving to include smart monitoring features, low-loss core materials, and modular designs. Some models now support IoT-based temperature, humidity, and load monitoring for predictive maintenance.
How to Choose the Right Model for Your Project
To select the most suitable dry-type transformer model, follow these steps:
1. Assess your power load and voltage requirements. 2. Evaluate the environmental conditions (humidity, temperature, dust). 3. Prioritize safety certifications and standards (IEC, ANSI, GB). 4. Consult a reputable transformer manufacturer or supplier. 5. Consider long-term maintenance and operating costs.
Select the Right Transformer, Boost Your System’s Efficiency
Dry-type transformers are essential for safe and stable power distribution across various sectors. By understanding the features of different models—SG, SCB, and SC—and aligning them with your project needs, you can ensure optimized performance, safety, and cost-effectiveness. Whether you’re planning an industrial installation or a smart urban infrastructure project, choosing the right dry-type transformer is a step toward energy-efficient and sustainable operation.
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