What is Dry Transformer?

Fire safety, oil-free operation, and minimal upkeep are driving demand. Buyers confused between oil-immersed and dry designs risk costly mistakes. The safer answer? Dry-type transformers¹, now a global standard for indoor projects.

What is a Dry-Type Transformer?

A dry-type transformer is one where the core and windings are cooled by air or resin instead of oil. With no flammable liquid, it reduces fire hazards and simplifies installation.

• VPI² (Vacuum Pressure Impregnated) – Coils varnished under vacuum and pressure.
• Cast Resin – Windings fully encapsulated, moisture- and dust-resistant.

Structure & Working Principle

Buyers fear overheating and fire risks. Dry-type transformers eliminate these by using air or resin insulation.

• Core & Windings – Copper/aluminum conductors with silicon steel.
• Insulation – Resin/varnish to block partial discharge.
• Enclosure – Shields from dust and contact.
• Cooling – Natural air (AN) or fan-assisted (AF).

Principle: Load generates heat → heat released to air → optionally cooled by fans → stable, fire-safe operation.

Types of Dry-Type Transformers

Choosing the wrong type raises risks. Buyers often select:

• VPI Transformer – Affordable, serviceable.
• Cast Resin Transformer – Fully encapsulated, robust in humidity.
• SCB Transformer – Popular resin type in IEC/GB markets.

Cooling: AN (natural air convection) or AF (fans assist cooling for higher load).

✅ Advantages of Dry-Type Transformers

• Fire-Safe – Non-flammable insulation.
• Reliable Indoors – Trusted in hospitals, metros, data centers.
• Eco-Friendly – No oil leaks, low environmental risk.
• Compact Footprint – Easy to install in tight spaces.
• Moisture Resistant – Cast resin excels in tropical regions.

⚠️ Disadvantages to Consider

• Higher Price – More costly than oil-immersed.
• Capacity Limits – Typically 50–3,150 kVA.
• Service Life – Around 20–25 years.
• Cooling Limits – Less efficient for extreme heavy loads.

Applications

Dry-type transformers are ideal for:

• Hospitals & Schools – Safer for public buildings. In Africa, adopted for indoor hospital and school projects.
• Data Centers – Dust-proof, reliable. In Southeast Asia, increasingly used in hyperscale centers for fire compliance.
• Underground Metro & High-Rise Buildings – Compact design fits tight basements.
• Commercial Spaces – Airports, malls, offices in the Middle East.

With demand rising, global buyers prefer to buy dry-type transformer from China, where certified factories act as reliable dry transformer supplier China partners.

Price Guide for Dry-Type Transformers

Capacity	Price Range (FOB China)	Notes
50–500 kVA	USD 40–60/kVA	Small commercial use
1000–2500 kVA	USD 60–90/kVA	Hospitals, data centers
Example: 1000 kVA 11/0.4 kV	USD 40,000–70,000	IEC/UL certified

Dry-Type vs. Oil-Immersed Transformer

Feature	Dry-Type Transformer	Oil-Immersed Transformer
Cooling Medium	Air / Resin	Mineral / Synthetic Oil
Fire Safety	Higher (non-flammable)	Lower (flammable oil)
Maintenance	Minimal	Regular oil testing
Service Life	20–25 years	25–30 years
Typical Capacity	50–3,150 kVA	50–25,000 kVA
Typical Use	Indoor, public infrastructure	Outdoor, utility-scale grids

Buyer’s Quick Takeaway

• Dry-type = safe, eco-friendly, compact footprint.
• Oil-immersed = outdoor, high-capacity, longer life.
• Match transformer type to project scale and safety codes.

FAQ

Q1: What is a dry-type transformer?
A transformer cooled by air or resin instead of oil, reducing fire risk and maintenance.

Q2: Main advantages?
Fire-safe, low maintenance, eco-friendly, compact, reliable indoors.

Q3: Where are they used?
Hospitals, schools, data centers, metros, malls, and airports. In Africa, schools and hospitals increasingly adopt dry-type transformers for safer indoor operations. In Southeast Asia, hyperscale data centers adopt them for fire compliance.

Q4: Price range?
USD 40–90/kVA FOB China. Example: 1000 kVA ~ USD 40,000–70,000. Buyers should compare quotes from multiple dry transformer suppliers in China to balance cost and quality. CIF quotes available.

Q5: How to choose a reliable supplier in China?
Check IEC/ISO certifications³, verify project references, and request test reports before placing orders with a dry transformer supplier China.

Conclusion

Dry-type transformers offer fire safety, eco-friendly design, and reliable indoor performance, making them the preferred choice for hospitals, metros, data centers, and high-rise projects worldwide. Compared to oil-immersed models, they trade higher upfront cost for safety, compliance, and low maintenance—critical factors for modern infrastructure.

✅ Final takeaway: Choose dry-type when fire safety, compact footprint, and indoor reliability matter most; choose oil-immersed for large outdoor grids and heavy-duty capacity.

👉 If you plan to buy dry-type transformer from China, request our 2025 price list and delivery schedule today. Partner with a trusted dry transformer supplier in China to secure cost, ensure compliance, and guarantee on-time delivery.

1. Dry-Type Transformer Overview ↩︎
2. Understanding Vacuum Pressure Impregnation Transformers ↩︎
3. IEC Standards for Transformers ↩︎

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