What is the difference between dry type transformers and oil immersed transformers？

In contrast, oil-immersed transformers adopt oil circulation cooling, where insulating oil acts as both a heat transfer medium and electrical insulator. The oil absorbs heat from the core and windings, circulates through internal oil channels, and releases heat via the transformer’s tank (often fitted with radiators or cooling fins). This design delivers excellent heat dissipation performance, particularly suited for large-capacity units, but introduces inherent limitations tied to the use of insulating oil.

Contents hide

1 Key Advantages of Dry-Type Transformers

2 Core Traits of Oil-Immersed Transformers

3 Applications & Configuration Options

4 Product Quality & Certification

Key Advantages of Dry-Type Transformers

Dry-type transformers stand out for their safety, versatility, and low lifecycle costs, making them a preferred choice for modern power systems:

Safety & Environmental Friendliness: Without flammable insulating oil, they eliminate risks of fire, explosion, or oil leakage—eliminating environmental pollution hazards. This safety profile allows direct installation in load centers (e.g., building basements, industrial workshops) without the need for separate fireproof rooms, complying with global electrical safety standards and building codes.
Exceptional Moisture Resistance: Engineered to operate reliably in environments with 100% relative humidity (under rated conditions). Unlike oil-immersed units, they require no pre-drying process after shutdowns or storage in humid spaces, enabling immediate re-commissioning and reducing downtime.
Low Operational & Maintenance Costs: Designed for long-term maintenance-free operation. Their air-cooled structure has no moving parts (in natural cooling mode) or only low-wear fans (in forced cooling), minimizing repair needs. The absence of oil-related maintenance (e.g., oil replacement, leakage checks) further lowers ongoing expenses.
Easy Installation & Space Efficiency: Compact design and lightweight construction simplify on-site installation, even in space-constrained areas. They integrate seamlessly into existing power systems, reducing installation time and labor costs compared to bulkier oil-immersed alternatives.

Core Traits of Oil-Immersed Transformers

While oil-immersed transformers excel in heat dissipation—making them suitable for high-power applications—their design comes with notable tradeoffs:

Heat Dissipation Performance: The oil-based cooling system efficiently handles high thermal loads, making them ideal for large-capacity transformers in power transmission and industrial settings.
Limitations: Insulating oil is flammable, requiring strict fire prevention measures (e.g., separate transformer rooms, oil retention tanks) that increase installation complexity and space requirements. Regular maintenance is mandatory, including oil quality testing, leakage inspections, and periodic oil replacement—adding to long-term operational costs. Oil spills also pose environmental contamination risks, restricting their use in dense urban areas, commercial buildings, or environmentally sensitive zones.
Cost Advantage: Their manufacturing process is relatively mature, resulting in a lower upfront purchase price compared to dry-type transformers. This makes them a cost-effective option for projects prioritizing initial investment over lifecycle costs, safety, or environmental impact.

Applications & Configuration Options

Dry-type transformers are versatile across residential, commercial, and industrial sectors. They are commonly used for:

Local lighting circuits, electronic equipment power supplies, and mechanical control systems.
Specialized industrial applications such as steam turbine auxiliary transformers, boiler power transformers, ash removal systems, dust collection units, and desulfurization equipment—typically with transformation ratios of 6000V/400V or 10KV/400V to supply 380V rated loads.
High-density areas like high-rise buildings, shopping malls, hospitals, airports, and subway stations, where safety and space efficiency are critical.

In terms of configuration, dry-type transformers offer two voltage regulation options: on-load voltage regulation (adjusting taps during operation for stable output under fluctuating loads) and no-load voltage regulation (adjusting taps when de-energized for fixed-load scenarios). They also come in cased and uncased designs—cased models provide extra protection against dust and physical damage, while uncased versions offer better heat dissipation and easier maintenance.

Product Quality & Certification

We specialize in manufacturing a comprehensive range of transformers, including dry-type (resin-insulated, cast-coil, etc.) and oil-immersed models. All products have obtained CE and ISO9001 certifications, adhering to international quality and safety standards. Our transformers are engineered with high-grade materials (e.g., oxygen-free copper windings, cold-rolled silicon steel cores) and undergo rigorous testing—ensuring stable performance, long service life, and reliability even in harsh operating conditions.