Transformer Copper Bar vs Aluminum Bar – Full Comparison

1. Conductivity & Resistivity

Copper BarHigher conductivity, lower resistivity. Current transmission loss is small, heat generation is low, more stable for long-term operation.

Aluminum BarLower conductivity, higher resistivity. Under the same cross-section, aluminum carries less current and generates more heat.

2. Mechanical Strength & Short-Circuit Resistance

Copper BarHigher tensile strength and hardness. Not easy to bend or deform under strong short-circuit electromagnetic force.

Aluminum BarSoft and lower mechanical strength. Easy to deform, twist or displace when short circuit occurs.

3. Oxidation & Corrosion Resistance

Copper BarGood anti-oxidation performance, stable chemical property, long service life inside transformer oil.

Aluminum BarEasy to oxidize and form oxide film on the surface, increases contact resistance, easy to cause overheating at connection points.

4. Connection Performance

Copper BarEasy to weld and bolt connection; contact performance is stable, not easy to loose or heat up.

Aluminum BarPoor welding performance; connection surface is easy to oxidize, long-term operation easily causes poor contact and overheating failure.

5. Size & Space Occupation

Copper BarSmall cross-section can meet large current demand, saves internal space of transformer.

Aluminum BarNeed larger width and thickness to reach the same current capacity, occupies more internal installation space.

6. Weight & Cost

Copper BarHigher density, heavier weight; raw material cost is higher.

Aluminum BarLight weight, lower material cost, more economical for low-end and small transformers.

7. Service Life & Stability

Copper BarLong service life, stable performance, low maintenance rate, suitable for medium and large power transformers.

Aluminum BarShorter service life, higher hidden failure risk, mostly used for small distribution transformers with low requirement.

Comparison Table