As the power industry moves toward higher efficiency, energy saving, and intelligence, the dry-type transformer has become widely adopted for its safety, eco-friendliness, and low maintenance. It is commonly used in urban distribution, rail transit, buildings, data centers, and renewable energy systems. This article provides a complete overview of dry-type transformer models, specifications, and technical trends to help engineers and buyers make informed decisions.
1. Definition and Features of Dry-Type Transformers
A dry-type transformer uses air or resin as the main insulation medium, with its core and windings not immersed in insulating oil. Compared with oil-immersed transformers, it offers the following advantages:
1) High safety — no risk of oil leakage or fire;
2) Eco-friendly — suitable for indoor and enclosed environments such as tunnels and buildings;
3) Simple maintenance — no need for oil testing or refilling;
4) Strong mechanical strength — high short-circuit resistance and operational reliability;
5) Excellent heat dissipation — performs well under high temperature and humidity.
Dry-type transformers are ideal for high-rise buildings, subways, airports, hospitals, shopping centers, wind farms, and photovoltaic power stations. They are the preferred choice for modern distribution systems.
2. Common Models of Dry-Type Transformers
Based on insulation type, cooling method, and performance standards, dry-type transformers can be divided into several major series:
1) SCB Series (Epoxy Cast Resin Type)
This series uses epoxy resin for insulation, providing excellent moisture, dust, and corrosion resistance. Typical models include:
• SCB10 Series — high efficiency, low noise, suitable for building and municipal systems;
• SCB11 Series — lower no-load loss and higher short-circuit strength compared to SCB10;
• SCB13 Series — the latest energy-efficient model with up to 30% lower losses and efficiency above 98%.
2) SG Series (VPI Type)
Manufactured using Vacuum Pressure Impregnation (VPI) technology with H-class insulation. It provides strong structural integrity and mechanical strength, suitable for applications requiring high reliability such as subways, hospitals, and airports. Common models include SG-150kVA, SG-800kVA, SG-1600kVA.
3) SH15 Series (Amorphous Alloy Core)
Uses an amorphous alloy core with extremely low no-load loss, providing superior energy savings. Ideal for factories and data centers with long-term high-load operation.
4) SBH Series (Smart Dry-Type Transformer)
Equipped with IoT sensors for real-time monitoring of temperature, humidity, voltage, and load, offering remote alarms and data analysis. It is a key component in modern smart grid systems.
5) KBSG Series (Explosion-Proof Dry-Type Transformer)
Designed for mines and underground tunnels, featuring explosion-proof, moisture-proof, and corrosion-resistant performance, typically rated IP54 or above.
3. Understanding Model Naming Rules
Example model: “SCB11-1000/10”
• S — three-phase transformer
• C — epoxy resin cast coil
• B — dry-type structure
• 11 — design sequence number (technical level)
• 1000 — rated capacity (kVA)
• 10 — rated high-voltage level (kV)
Although naming may vary slightly across manufacturers, the general logic remains consistent. When selecting a transformer, focus on rated capacity, voltage level, and efficiency class.
4. Main Technical Parameters and Performance Indicators
Key technical parameters for dry-type transformers include:
Rated Capacity: 100kVA–3150kVA
Rated Voltage: 6kV, 10kV, 20kV, 35kV
Vector Group: Dyn11 or Yyn0
Insulation Class: F-class or H-class (155°C/180°C)
Cooling Method: AN (Air Natural) or AF (Air Forced)
Noise Level: ≤50–65dB
Protection Level: IP20 (indoor), IP23 (drip-proof)
High-performance dry-type transformers often use H-class insulation materials, high-efficiency magnetic cores, and intelligent temperature-controlled fans to maintain low temperature rise and high efficiency under full load.
5. Price and Selection Guidelines
The price of a dry-type transformer depends on several key factors:
1) Rated Capacity — larger capacity requires more copper, iron, and resin;
2) Model and Efficiency — SCB13 and SH15 series are more expensive but save more energy;
3) Cooling Method — AF (forced air cooling) units cost more than natural cooling ones;
4) Special Features — explosion-proof or intelligent monitoring options increase cost;
5) Material Costs — fluctuations in copper and epoxy resin prices affect total price.
Generally, a 1000kVA dry-type transformer costs between USD 8,000 and 15,000. Although amorphous alloy or smart models are more expensive, they save significant energy and pay for themselves in 3–5 years.
6. Latest Technical Trends and Innovations
With the advancement of energy conservation and smart grid development, dry-type transformers are evolving in the following directions:
1) Higher Efficiency: Using amorphous alloy cores and high-grade silicon steel to reduce no-load loss by over 30%;
2) Intelligent Monitoring: IoT-based real-time data tracking for temperature, load, and humidity, with cloud connectivity;
3) Low Noise and Eco-Friendly Design: Optimized magnetic path and recyclable materials for sustainable operation;
4) Enhanced Fire and Moisture Resistance: Suitable for tunnels, coastal zones, and humid areas;
5) Modular and Integrated Systems: Supporting prefabricated substations and outdoor compact installations to simplify engineering work.
Future dry-type transformers will be integrated into renewable energy storage systems, EV charging stations, and data centers, playing a crucial role in smart energy infrastructure.
From SCB10 to SCB13, and from SG to SBH intelligent series, dry-type transformer technology continues to evolve toward higher efficiency, safety, and intelligence. Understanding the characteristics of each model helps engineers and procurement teams achieve the best performance-cost ratio. With growing demand for green energy and digital grids, dry-type transformers are becoming the preferred choice over traditional oil-filled designs.
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