Introduction of Copper Foils For Transformer Windings
In modern power and distribution transformer manufacturing, transitioning from traditional round or rectangular magnet wires to high-purity copper foil windings is essential for optimizing efficiency and reducing coil dimensions.
LP Industry supplies premium-grade Cu-ETP (C11000) and Cu-OF (C10200) copper foils designed specifically for low-voltage (LV) and high-power transformer coils. Featuring micro-burr precision slitting (<0.02 mm), smooth chamfered edges, and high electrical conductivity (≥100% IACS), our copper strips eliminate inter-layer insulation breakdown while drastically improving space factor and thermal dissipation. High-purity (>99.9%) copper foils also engineered for low eddy-current loss, superior thermal dissipation, and short-circuit withstand strength. Fully compliant with ASTM B187, EN 13599, and IEC 60317 standards.
Copper Foils For Transformer Winding is widely sold in the world with high performance, also called transformer Copper Coils. The commonly used copper grades are ETP Grade (Electrolytic Tough Pitch), C11000, UNS C10200 TU1, temper O or H state.
Copper Foils For Transformer Winding Technical parameters
| Name | Copper Foil |
| Material Grade | Cu-ETP (C11000 / T2 / E-Cu58), Oxygen-Free (C10200 / TU1) |
| Copper Purity | ≥ 99.9% / Conductivity ≥ 99.80% IACS |
| Electrical Conductivity | ≥ 100% IACS (Electrical Resistivity ≤ 0.017241 Ω·mm²/m at 20°C) |
| Thickness Range | 0.1mm – 4.0mm (Tolerance ≤ ±5μm) |
| Temper | Soft(O) / Hard(H) |
| Dimension | Thickness: 0.1-4.0mm; width: 20-1500mm / Custom slitting width available |
| Standard | ASTM,EN 13599 / GB-T 18813-2002 |
| Packing: | In coil, Inner Diameter: 300mm, 400mm, 500mm, etc. |
| Properties | Value |
| Denstity(g/cm3) | 8.9 |
| Tensile strength(Mpa) | Min. 220 |
| Yield strength(Mpa) | Max.120 |
| Elongation(%) | Min.40 |
| Hardness | HV ≤ 70 |
| Thermal Conductivity W/(K.m) | 400 |
| Electrical conductivity | Min. 100% IACS |
| Chemical Composition (%) | ||
| Cu+Ag | P | Fe |
| 99.99 | ＜0.001 | ＜0.001 |
Core Advantages & Pain-Point Solutions
Burr-Free Edge Protection (Zero Insulation Damage)
Industry Challenge: Standard slit edge burr is sharp so it punctures inter turn nomex paper, DMD or insulation film easily and cause turn to turn short.
Our Solution: The cutting edge will be treated online by the high-precision rotary shear slitting and online deburring technology. The burr height is controlled by less than 0.02 mm. The insulation layer will be offered the best mechanical protection.
High Space Factor & Superior Heat Dissipation
Foil-wound coils have a fill factor of more than 90% in comparison to round wire windings. The contact of layers between surfaces permits the heat produced inside the transformer to flow outwards preventing the formation of hot spots and increasing the service life of the equipment.
Reduced Eddy Current Loss & High Short-Circuit Withstand
The foil windings counteract the distribution of axial currents along the length of the coil, significantly reducing the effect of axial electrodynamic forces under short circuit conditions. It also dramatically diminishes the resultant stray eddy current losses.
The manufacturing process of transformer copper strips
it includes continuous up-casting, continuously extruded, milling face, rolling, welding, milling face, high annealing, rolling, low-temperature annealing, Cleaning and Passivation, aligning, cutting, chamfering, the main method by welding, the width for improving copper strips, meets the width requirement of transformer copper strips.
The standard of Copper Foil
| INDUSTRY | USA | ITALY | CHINA | EURONORM | JAPANESE | |
| STANDARD | ASTM B5, B152 | UNI 5649 | GB/T | EN 1652 | DIN 1976 | JIS |
| C1100 | C11000 | Cu-ETP | T2 | CW004A | E-Cu 58 | C1100 |
Primary Industry Applications
Cast Resin Dry-Type Transformers; which are excellent for use in LV windings of commercial, industrial and offshore power installations.
Oil-Immersed Power & Distribution Transformers: High-conductance strip windings for network substations.
Reactors & Inductors: Heavy duty industrial reactors and magnetic components at high frequencies
Solar & Wind Energy Inverters: Windings used in step-up transformers for renewable energy.
Quality Assurance & Packaging
To ensure zero oxidation and damage during long-distance ocean shipping:
Anti-Oxidation Treatment: Every coil is degreased and surface-passivated to prevent tarnishing during storage.
Export-Grade Protection:
Inner layer wrapped with moisture-proof plastic film and VCI anti-rust paper.
Silica gel desiccant packs added.
Secured on heavy-duty wooden pallets or fumigated wooden crates with edge protectors to prevent compression damage.
Frequently Asked Question
A: Copper foil is used in the LV windings of dry-type transformers, reactors and distribution transformers mainly to reduce the eddy current loss, enhance the mechanical strength when subjected to short-circuit stress, and optimize the heat dissipation.
A: Serrated burrs can cause the inter-turn insulation paper or Nomex film to be pierced with the possibility of short circuit and insulation breakdown during operation of transformer. /LP Industry offers deburred and rounded edges to minimize the damage to the insulation materials to zero.
A: Our thickness control is maintained within ±5 microns, and width tolerance is within ±0.2mm, meeting ASTM B187 and IEC standards
