Dry type Transformer are indispensable devices in power systems, responsible for the transmission and transformation of electrical energy. Among various types, dry type and oil-immersed transformer are the most common. With increasing industrial safety and environmental standards, dry-type transformers have become a focus for B2B customers due to their unique advantages.
In this article, we dive deep into the core differences between these two types, helping you better understand which transformer suits your project needs.
A dry-type transformer is a transformer that uses no liquid insulating medium; its insulation and cooling rely mainly on air. Common types include resin cast transformers and open-type transformers. These are widely used in locations requiring high safety and environmental protection, such as large commercial buildings, subway systems, and hospitals.
| Type | Definition | Features |
|---|---|---|
| Resin Cast Transformer | Coil and core encapsulated with epoxy resin | Excellent fire resistance, suitable for high-safety sites |
| Open-type Dry Transformer | Exposed coils cooled directly by air | Faster heat dissipation, requires high dust and moisture protection |
The differences between dry type transformer and oil-immersed transformer are reflected in cooling methods, safety, maintainability, environmental impact, application and cost.
While dry-type transformers generally have higher upfront costs and are limited to medium and small capacities, their eco-friendly and low-maintenance nature often offsets these drawbacks. In contrast, oil-immersed transformers cover wider voltage and capacity ranges but need more rigorous safety and environmental control measures. Thus, the choice between them depends on specific operational, safety, and environmental needs.
| Comparison Aspect | Dry-type Transformer | Oil-immersed Transformer |
|---|---|---|
| Cooling Medium | Air-cooled, natural or fan-assisted | Oil-cooled, oil circulates to radiators for heat dissipation |
| Maintenance | Simple maintenance, no oil testing or replacement needed | Requires regular oil quality check and maintenance |
| Safety | Oil-free, fire and explosion resistant, ideal for high safety areas | Oil is flammable, risk of leaks, needs safety safeguards |
| Environmental Impact | Environmentally friendly, no oil leakage risk | Risk of oil pollution, requires containment |
| Application Scenarios | Indoor, power distribution, high-rise buildings, hospitals | Outdoor, high capacity, high voltage load |
| Capacity & Voltage Range | Typically suitable for medium to small capacities (≤2500kVA), low voltage (≤35kV) | Wide range, from small to ultra-high voltage (up to 1000kV) |
| Cost | Higher purchase cost but saves on fire safety and environmental facilities | Lower initial cost but higher maintenance and safety expenses |
| Load Handling | Operates near rated capacity, limited overload capability | Good overload capacity, suitable for heavy loads |
| Structure | Coil and core visible, epoxy resin encapsulated or open structure | Sealed oil tank, coils immersed in insulating oil |
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1️⃣High Safety and Fire Resistance: Oil-free design greatly reduces fire and explosion risks, perfect for densely populated or high-safety locations.
2️⃣Environmentally Friendly: No oil leaks, green and compliant with environmental regulations.
3️⃣Easy Maintenance: No need for oil quality checks or oil replacement, saving labor and cost.
4️⃣Compact and Flexible Installation: Ideal for indoor use, space-saving, suitable for installation in buildings or factories.
❶ Higher Initial Investment: Typically 20-30% higher purchase cost than oil-immersed transformers.
❷ Limited Cooling Capability: Requires controlled temperature and humidity; weaker overload capacity.
❸ Capacity Limits: Best suited for medium and small capacities; challenging for large loads.
| Advantage | Explanation | Disadvantage | Explanation |
|---|---|---|---|
| High Safety | No oil fire risk, good explosion resistance | High Investment | Higher material and design costs |
| Easy Maintenance | No oil testing or change required | Cooling Limitations | Air cooling less efficient |
| Environmentally Friendly | No oil leakage, regulation-compliant | Capacity Restrictions | For medium and small loads only |
| Flexible Installation | Suitable for complex indoor environments | Sensitive to Humidity | Requires dust and moisture control |
Dry-type transformers are increasingly applied in industries requiring high safety, environmental protection, and reliability:
| Industry | Applications | Selection Reasons |
|---|---|---|
| Commercial High-rises | Offices, Shopping Malls | Indoor installation, fire safety, easy maintenance |
| Medical Institutions | Emergency Rooms, Labs | Stable power, high safety standards |
| Subway and Rail Transit | Subway Stations and Equipment Rooms | Strict fire and explosion resistance |
| Data Centers | Server Rooms | Low noise, pollution-free, equipment safety |
| Renewable Energy | Wind and Solar Power Stations | Green, energy-saving, adaptable to environments |
👉Consider Environmental Requirements
If safety and environmental regulations are strict (e.g., indoor public buildings, hospitals), dry-type transformers are recommended.
👉Capacity Needs
Dry-type transformers suit medium and small capacities (generally ≤2500kVA); oil-immersed transformers are better for larger loads.
👉Budget Consideration
While dry-type transformers have higher upfront costs, they save on maintenance and safety costs in the long run.
👉Maintenance Resources
Low maintenance needs suit customers with limited service resources.
👉Installation Conditions
For indoor use, dry-type is preferable, especially where moisture and dust control can be ensured.
| Selection Factor | Dry-type Transformer | Oil-immersed Transformer |
|---|---|---|
| Environmental Safety | High | Requires extra safety measures |
| Capacity Range | Medium and small | Wide range, including ultra-high |
| Initial Investment | Higher | Lower |
| Maintenance Frequency | Low | Higher |
| Suitable Installation | Indoor, high-rise buildings, hospitals | Outdoor and heavy load areas |
Interested in dry-type transformers? Contact us to learn more about our products and customized solutions. We are ready to provide you with professional and efficient service.
Dry type transformer stand out as the preferred option for many safety- and environmentally-conscious locations due to their superior safety, environmental friendliness, and easy maintenance. Although they have a higher initial cost and limited load capacity compared to oil-immersed transformers, their long-term savings and safety benefits make them a key choice for sustainable power distribution.
By choosing wisely and applying appropriately, dry type transformers help businesses raise electric safety levels and contribute to sustainable development. If you’re seeking reliable, safe, and green power solutions, dry-type transformers are your trusted partner.
For more information or consultation, feel free to contact us. Let our experts tailor the best solution for your needs.
A dry-type transformer uses air instead of oil for insulation and cooling. It is safer, environmentally friendly, and ideal for indoor and high-safety environments.
Maintenance is usually annual in clean environments and every six months in humid or dusty areas, focusing on cleaning and inspection.
Yes, but typically only in moderate climate conditions and with proper protective enclosures to prevent moisture and dust ingress.
They have higher fire safety, lower maintenance needs, no risk of oil leakage, and are more environmentally friendly.
They are best suited for medium and small capacities (generally ≤2500kVA). For larger capacities, oil-immersed transformers are more common.
Common causes include dust accumulation, loose connections, and prolonged overload conditions.
Consider your installation environment, safety requirements, capacity needs, budget, and maintenance resources.
Maintenance is simpler than oil transformers but requires knowledge of electrical safety and inspection of insulation and cooling systems.
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