HUARUI 
Customizable Dry Type Transformer Winding Coil
This low-voltage foil-wound coil for dry-type transformers is a core replacement component specifically designed for dry-type transformers. It supports full-specification customization and is compatible with 30kVA~6300kVA SCB and SG series epoxy resin cast transformers. It can be used for new machine assembly, old transformer repair and replacement, and equipment upgrades. The coil uses high-purity oxygen-free copper/aluminum foil as the main conductive material, combined with H-grade high-temperature resistant insulation material. It undergoes fully automated foil winding, argon arc welding, and vacuum pressure impregnation (VPI)/vacuum epoxy casting curing, resulting in a robust and stable integrated insulation structure. The product features rapid heat dissipation, short-circuit resistance, low loss, low partial discharge, moisture resistance, and flame retardancy. It comes with a complete set of insulation support components, lead copper busbars, and end sealing structures, supplied as a complete set without additional processing. It directly adapts to the core assembly of dry-type transformers of corresponding capacity and is a universal spare part for transformer manufacturers, power maintenance units, and complete electrical equipment companies.
CNC foil winding equipment winds at a uniform speed, with longitudinally reserved uniform heat dissipation air channels, solving the helix angle problem of traditional round conductor windings. Ampere-turn distribution is highly balanced, leakage flux loss is significantly reduced, and overload heat dissipation capacity is improved by more than 30%.
Seamless fusion welding of copper foil and outgoing copper busbars ensures no incomplete welds or porosity, resulting in extremely low contact resistance and preventing detachment and cracking under short-circuit impact.
· Non-encapsulated dry-type transformer coil: Multiple VPI vacuum pressure impregnation and high-temperature curing ensure thorough penetration of insulating varnish into each layer, providing moisture resistance, salt spray resistance, and resistance to damp heat.
· Epoxy-cast dry-type transformer coil: Vacuum environment epoxy resin pressure casting eliminates internal air bubbles and cavities, resulting in partial discharge ≤5pC, high insulation strength, and flame retardant self-extinguishing properties.
After coil winding, welding, and insulation wrapping, the coil is placed in a constant temperature oven for segmented curing, eliminating internal stress and reducing the risk of cracking during thermal cycling. Suitable for outdoor and underground environments with large temperature differences.
CNC integrated molding ensures that the inner diameter, height, and air duct dimensions strictly match the standard dry-type transformer core. Replacing old coils requires no modification to clamps or fixtures, facilitating easy assembly and disassembly.
| Superior Short-Circuit Resistance | The foil-wound structure provides balanced ampere-turns, effectively canceling out axial impact forces generated by short circuits. The coil is less prone to deformation and disintegration, passing national standard short-circuit withstand tests, making it suitable for power grid and new energy source harmonic impact conditions. |
| Low Loss & Low Temperature Rise | High conductor fill factor and uniform heat dissipation channels result in a winding temperature rise 10–15 K lower than traditional round wire coils of the same capacity. This leads to lower long-term energy consumption and extends the overall lifespan of the transformer. |
| Excellent Electrical Safety Performance | Integrated solid insulation, non-flammable and non-explosive, produces no toxic fumes upon combustion; partial discharge performance far exceeds national standards; resistant to lightning strikes and overvoltages, suitable for enclosed indoor locations such as high-rise buildings, hospitals, data centers, and subways. |
| Three-Proof Weather Resistance | Moisture-proof, dust-proof, and salt spray-proof, allowing for long-term stable operation in high-humidity, dusty, and coastal salt spray environments with minimal maintenance. |
| Flexible Customization & Adaptation | Supports customized capacities from 30 kVA to 6,300 kVA, low voltage 0.4 kV / 0.69 kV, different impedances, heights, and inner diameters; can be supplied as a complete package with corresponding HV coils, insulation accessories, and iron cores. |
Civil Buildings
Dry-type transformers for indoor power distribution in office buildings, residential communities, shopping malls, hospitals, and schools;
Industrial Plants
Repair and replacement of high-power dry-type transformers in factories, mines, chemical plants, and sewage treatment plants;
New Energy Industry
Coil spare parts for dry-type transformer equipment in photovoltaic, wind power, and energy storage systems;
Special Locations
Enclosed dry-type transformers for subways, tunnels, underground utility tunnels, data centers, and computer rooms;
Equipment Maintenance
Complete machine matching and old equipment renovation and replacement for power maintenance companies and transformer manufacturers.
Compatible Capacity: 30kVA-6300kVA (customizable);
Low Voltage Standard Voltage: 400V, 690V (customizable);
Insulation Class: F (155℃), H (180℃);
Structure Type: Epoxy-reinforced foil wound coil
Conductor Material: All-copper foil, aluminum foil optional.
1. Conductive Conductors (Two Options)
All-Copper Version (Mainstream High-End Configuration): Uses T2 high-purity oxygen-free copper foil, with a purity ≥99.99%. Excellent conductivity, low DC resistance, and low copper loss during operation. The copper foil undergoes annealing stress relief treatment, resulting in high toughness, resistance to cracking and deformation, and lower temperature rise during long-term full-load operation. The lead copper busbar is integrally formed, argon-arc welded, and the contact surface is silver-plated, ensuring stable conductive contact and eliminating the risk of overheating.
Aluminum Foil Version (Economy Type): High-purity electrical aluminum foil, lightweight and lower cost, suitable for light-load, cost-priority projects. The surface undergoes anti-oxidation passivation treatment, paired with a dedicated transition copper-aluminum connector to prevent electrochemical corrosion, suitable for long-term stable operation scenarios.
2. Complete Insulation System
Interlayer Insulation: DMD pre-impregnated composite insulating paper, DuPont Nomex high-temperature resistant insulating paper, H-class 180℃ heat resistance, high breakdown voltage, and aging resistance;
Inner and Outer Cylinder Insulation: Reinforced with fiberglass pre-impregnated cloth to enhance the overall mechanical strength of the coil;
End Sealing: Solvent-free epoxy resin/high-temperature impregnated varnish for integral sealing and curing, preventing moisture and dust intrusion;
Supporting Insulation Components: Epoxy fiberglass support strips and insulating pads, providing high insulation strength, cushioning and shock absorption, and reducing operating noise.
1. Custom mold making based on customer transformer drawings and old coil samples;
2. Provide complete sets of high and low voltage coils, simultaneously supplying a full set of spare parts such as insulation blocks, support bars, and lead copper busbars;
3. Provide resistance testing, withstand voltage, and partial discharge testing reports upon delivery, conforming to GB/T and IEC standards;
4. Fast delivery of in-stock standard capacity coils; controllable lead time for large-scale customization; support for batch manufacturing.
