Comparison between Dry-type copper wound and Dry-type aluminum wound Transformers

Dry Type Transformer

Dry-Type Copper Wound Transformer - A dry-type copper wound transformer is a transformer that uses copper conductors in its windings and relies on air or resin insulation instead of oil for cooling. Known for their high electrical conductivity, durability, and efficiency, these transformers are ideal for critical and long-term installations where performance and reliability are key.

Dry-Type Aluminum Wound Transformer - A dry-type aluminum wound transformer uses aluminum conductors in the windings and is similarly air- or resin-insulated, eliminating the need for oil. These transformers are lighter and more cost-effective, making them suitable for installations where budget and ease of handling are more important than maximum efficiency.

1. Conductor Material 

Copper

• Higher electrical conductivity (\~59.6 MS/m)
• Requires a smaller conductor cross-section

Aluminum -

•  Lower conductivity (\~36 MS/m)
•  Requires a larger conductor size for the same current

Best - Copper

2. Resistance

Copper -

•  Lower electrical resistance
•  Reduces I²R losses

Aluminum -

• Higher resistance
• More heat and power loss

Best - Copper

3. Heating & Thermal Performance -

Copper-

• Better heat dissipation
• Lower temperature rise
• Less thermal expansion

Aluminum -

• Heats up more
• Higher thermal expansion (can cause joint issues)

Best - Copper

4. Efficiency -

Copper -

• Higher energy efficiency
• Better for long-term power savings

Aluminum - 

• Slightly lower efficiency

Best - Copper

5. Losses - 

Copper -

• Lower copper (I²R) losses

Aluminum - 

• Higher copper losses

Best - Copper

6. Size and Weight - 

Copper - 

• Compact winding size
• Heavier due to high density

Aluminum - 

• Larger windings
• Lighter and easier to handle

Best - Aluminium (for weight-sensitive setups)

7. Life Expectancy - 

Copper - 

• Longer lifespan
• Stronger mechanical strength
• Less prone to oxidation

Aluminum - 

• Shorter lifespan
• Higher risk of connection issues over time

Best - Copper

8. Oil & Insulation (Dry-Type Specific)-

Both - Use air or resin for cooling, no oil required, environmentally friendly

Best - Equal

9. Indoor/Outdoor Suitability - 

Copper - 

• Excellent in harsh outdoor environments

Aluminum - 

• Acceptable, but more prone to corrosion

Best - Copper

10. Mechanical Strength & Reliability -

Copper -

• Stronger
• Withstands vibrations and short-circuits better

Aluminum - 

• Softer metal
• Lower mechanical endurance

Best - Copper

11. Cost Consideration

Copper - 

• Higher initial cost
• Lower lifetime cost due to durability and efficiency

Aluminum - 

• Lower initial cost
• Higher total cost due to greater losses

Best - Aluminium (when budget is a constraint)

12. Installation & Handling - 

Copper -

• Heavier and harder to move/install

Aluminum - 

• Facilitated transportation and installation owing to reduced weight

Best - Aluminum

13. Accuracy (Voltage Regulation)-

Copper -

• Lower voltage drop
• Tighter voltage regulation

Aluminum - 

• Higher voltage drop under load

Best - Copper

So, lets check in below-

Factors                   /                         Suitable

..................................................................................................................................

In Efficiency                             -           Copper        

Mechanical Strength & Life  -           Copper        

Heating & Thermal Stability -          Copper       

Price                                           -          Aluminum

Weight & Portability               -          Aluminum

Durability outdoors                 -         Copper  

Handling & Transport             -         Aluminum

Final Recommendation - 

• Choose a copper-wound transformer for high efficiency, long life, critical loads, and reliable performance.
• Choose an aluminum-wound transformer for budget-conscious applications, lighter installations, or temporary use.

- GGJ