Pure Copper Strip (C11000) for Power Transformers

Copper-ETP (C11000) Strip for Power Transformers

Modern transformers are typically required to operate continuously and reliably for 20 to 30 years or even longer, while maintaining high energy efficiency and low maintenance costs. Therefore, the performance of winding conductor materials directly determines transformer copper loss, temperature rise, mechanical strength, and long-term operational reliability.

Compared with other conductive materials, C11000 Electrolytic Tough Pitch Copper (ETP Copper) has an electrical conductivity of approximately 99.9% IACS. With high copper purity and low impurity content, it provides outstanding electrical and thermal conductivity, making it one of the most widely used high-conductivity materials in the power equipment manufacturing industry.

As global smart grids, renewable energy projects, and transmission and distribution networks continue to expand, the market for high-performance transformer copper strip is maintaining steady growth.

Product Features of C11000 Pure Copper Strip

1.Ultra-High Electrical Conductivity

C11000 copper strip has a resistivity of only 1.724 μΩ·cm, and its conductivity is about 40% higher than aluminum materials, significantly reducing resistance loss.

2.Excellent Mechanical Properties

It offers a balanced combination of tensile strength and ductility, making it easy to process into strips or coils.

3.Excellent Thermal Stability

C11000 copper maintains a stable structure at elevated temperatures and offers good oxidation resistance.

4.Low Impurity Content

The content of impurities such as oxygen, iron, and silicon is extremely low, reducing the degradation of electrical performance.

Typical Product Specifications

Why Choose C11000 ETP Copper Strip for Power Transformers?

1. High Electrical Conductivity

The electrical conductivity of C11000 pure copper strip reaches 100%–101% IACS, which can significantly reduce winding resistance, decrease energy waste, and improve the overall conversion efficiency of transformers.

2. Good Thermal Conductivity

C11000 has a thermal conductivity of approximately 401 W/(m·K), enabling rapid transfer of heat generated by the windings and improving internal temperature distribution. It effectively reduces the risk of local overheating and greatly enhances operational stability and safety margins.

3. Excellent Ductility

In the annealed condition, C11000 pure copper strip can achieve an elongation of more than 45%. It has excellent ductility and formability, making it suitable not only for conventional foil windings and layer windings, but also for special irregular winding structures.

4. High Dimensional Accuracy

The thickness tolerance of C11000 copper strip can usually be controlled within ±0.005 mm, with stable width accuracy, providing reliable support for automated precision winding.

5. Superior Surface Quality

C11000 pure copper strip for power transformers requires a smooth surface, flat edges, and no burrs. Burr height is usually controlled at ≤0.01 mm. Excellent surface quality reduces potential risks during winding processing and helps protect insulation materials.

Application Scenarios of Transformer Copper Strip

Power Transformers

Mainly used for high-voltage and low-voltage winding manufacturing, ensuring excellent conductivity and long-term operational stability.

Distribution Transformers

Effectively reduces no-load loss and load loss, improving the operating efficiency of power distribution systems.

Dry-Type Transformers

Widely used in cast-resin dry-type transformers for hospitals, airports, commercial buildings, industrial plants, and other locations.

Renewable Energy Transformers

Widely applied in supporting transformers for photovoltaic power generation, wind power generation, and energy storage systems, providing stable and reliable power transmission for renewable energy systems.

Instrument Transformers

Suitable for current transformer (CT) and voltage transformer (VT) windings, where high conductivity and dimensional accuracy are required.

Reactors and Inductive Equipment

Also widely used in the winding manufacturing of various reactors, inductors, and other electromagnetic equipment.

Common Temper Options for C11000 Pure Copper Strip

Different transformer structures and processing methods have different requirements for copper strip temper. C11000 pure copper strip is usually available in soft, half-hard, and hard tempers.

Soft Copper Strip (O Temper)

The copper strip is fully annealed, completely eliminating work-hardening stress inside the material.

Soft copper strip has excellent ductility and bending performance, making it suitable for transformer foil windings and applications requiring large deformation. For products with demanding winding requirements, soft copper strip can reduce cracking and strip breakage.

Half-Hard Copper Strip

Half-hard copper strip combines certain strength and plasticity. It is suitable for conductive connectors, lead components, or winding structures that require a certain degree of support.

Hard Copper Strip

Hard copper strip has higher strength and good dimensional stability, but relatively lower plasticity. It is suitable for conductive structural parts with small deformation and higher mechanical strength requirements.

When selecting the appropriate temper, companies should comprehensively consider transformer capacity, winding form, processing equipment, insulation system, and product design standards.

The Transformation from Copper Wire to Copper Strip

Traditional transformer windings mostly use round copper wire or rectangular copper wire. The rise of copper strip/copper foil windings represents an important upgrade in transformer manufacturing technology.

C11000 pure copper strip is mainly used in the production of windings for foil-wound transformers, as well as transformer flexible connections and amorphous alloy transformers. Compared with copper wire windings, copper strip windings offer the following significant advantages:

• Higher Space Utilization: Copper strip can be wound tightly with smaller interlayer gaps, effectively reducing transformer volume.

• Better Heat Dissipation: The flat surface of copper strip provides a shorter heat conduction path, which facilitates rapid heat dissipation from the windings.

• Stronger Short-Circuit Resistance: The foil-wound structure has high mechanical strength and can better withstand electrodynamic impacts caused by short-circuit currents.

• Higher Automation Efficiency: Copper strip windings are suitable for automated foil winding machines, offering high precision and fast production efficiency.

Quality Requirements for C11000 Pure Copper Strip Used in Power Transformers