High Conductivity Copper Strip For Transformer
2026-09-23
When designing and selecting high-efficiency, energy-saving transformers, the conductivity of the winding material directly determines the unit's load losses and energy efficiency rating. Haomei Aluminum has long specialized in the R&D and export of high conductivity copper strips for transformer windings. Our copper strip product range includes the T2 (Chinese GB standard) and C11000 (US ASTM standard) grades. Through precision melting and controlled annealing processes, we consistently achieve conductivity levels of 100%–101% IACS, providing global transformer manufacturers with winding base materials characterized by low losses and high consistency.
The upper limit of conductivity is determined by material purity. We utilize high-purity cathode copper as the raw material, processed via vertical continuous casting and multi-pass cold rolling. For both T2 and C11000 grades, the combined copper and silver content is no less than 99.90%; harmful impurities such as bismuth, antimony, arsenic, and lead are strictly limited, and oxygen content is controlled below 0.02%. The chemical compositions of these two grades align closely: T2 is a standard tough-pitch copper under China's GB/T 5231 standard, while C11000 is an electrolytic tough-pitch copper under the US ASTM standard. Their performance metrics are essentially equivalent, allowing for flexible material selection based on the client's regional standards. Impurity elements create electron scattering centers within the copper crystal lattice; even minute increases in impurities result in a measurable drop in conductivity. Thanks to this precise compositional control, our finished copper strips exhibit a room-temperature resistivity as low as approximately 0.0172 Ω·mm²/m, with conductivity consistently ranging from 100% to 101% IACS (and reaching nearly 102% IACS in some batches). For a given current-carrying cross-section, higher conductivity translates to lower DC resistance and reduced Joule heating losses, directly enabling transformers to meet S13, S15, or even higher energy efficiency standards.
Transformer windings typically involve the continuous winding of hundreds or even thousands of meters of copper strip; performance fluctuations in a single coil can directly accumulate into quality risks for the entire unit. We utilize a bright annealing production line with a protective atmosphere, employing precise, zone-based temperature control to achieve complete recrystallization. This ensures the T2/C11000 copper strip reaches a stable "O-temper" (soft) state, with Vickers hardness controlled between HV55 and HV65, a cross-width hardness deviation of no more than HV5, and an elongation at break of ≥35%. This high uniformity in hardness and elongation ensures smooth feeding and consistent bending/fitting on high-speed foil winding machines. The resulting windings feature minimal inter-turn gaps and a high winding fill factor, effectively raising the partial discharge inception voltage. Years of export experience show that fluctuations in hardness and conductivity between batches are the most common issues customers face during mass production; our comprehensive in-line inspection and coil-by-coil material reporting system are the keys to ensuring batch-to-batch consistency.
Haomei copper strip for transformer products range in thickness from 0.1 mm to 3.0 mm, with widths slit to custom specifications based on winding designs. Thickness tolerance is controlled within ±0.005 mm, and edge straightness is ≤1 mm/m. Strip edges undergo specialized rounding to remove slitting burrs and sharp corners, preventing partial discharge caused by protrusions between winding layers. Surfaces are thoroughly cleaned to ensure freedom from residual oil, oxidation spots, and roll marks, making them immediately compatible with insulation paper wrapping and vacuum impregnation processes. Supply in large coil weights reduces the number of intermediate joints in the winding, minimizing welding defects and resistive losses at joints, thereby further enhancing the overall reliability of the equipment.
Haomei T2 and C11000 high-conductivity copper strips comply with both domestic and international standards, such as GB/T 2059 and ASTM B152. Each shipment includes comprehensive material certification and performance test reports. We offer customization options—including anti-oxidation tin plating and vacuum moisture-proof packaging—to meet diverse needs. Our products are widely used in dry-type transformers, oil-immersed transformers, step-up transformers for PV and wind power, and high-frequency reactors. We provide full-cycle technical support—from material selection consultation and specification customization to mass delivery—enabling customers to achieve the mass production and upgrading of high-efficiency, energy-saving transformers through consistent material quality.
Choosing high-conductivity copper strips is essentially an investment in the energy efficiency and reliability of transformers throughout their entire lifecycle. With stable material performance, precise dimensional control, and professional export services, Haomei is committed to partnering with global transformer manufacturers to drive the upgrade of power equipment toward greater efficiency.