Product Introduction
Combined Flat Transposed Cable is a customized aluminum flat transposed winding conductor, designed for heavy-duty oil-immersed transformers, high-voltage shunt reactors (up to 1100kV), metallurgical rectifier equipment and lightweight mobile power stations.
Base Raw Material: Our Self-Produced Bare Aluminum Wire
All conductive strands adopt our self-produced round & flat bare aluminum wire as the core conductor. Our professional aluminum bare wire workshop is a supporting core production line for transposed cable manufacturing. We adopt 1350 high-purity electrical aluminum (purity ≥99.7%) without any surface insulation coating. Every batch of bare aluminum wire is inspected by eddy current non-destructive flaw detector in full process, which can effectively detect internal inclusions, air holes and surface cracks. The products are available in soft and half-hard temper, featuring low resistivity and smooth burr-free surface. Our self-produced bare aluminum wire is not only the exclusive internal raw material for transposed cables, but also available for direct sales to transformer, cable and motor manufacturers. Stable raw material quality guarantees defect-free film wrapping and precise transposition forming of finished products.
Insulation Structure
- Single aluminum strand insulation: Each round bare aluminum wire is wrapped with DuPont Mylar PET Polyester Film (Class B/F) or DuPont Kapton PI Polyimide Film (Class H) by professional lapping equipment, no enamel coating is adopted.
- Combined transposition assembly: Multiple groups of insulated bare aluminum strands with different specifications (step-size bundles / internal screen wire bundles) conduct continuous position conversion at fixed intervals, and are compacted into an integrated flat rectangular structure.
- Outer overall wrapping: The whole transposed bundle is wrapped with DK composite insulation paper, DM composite paper, glass cloth tape or polyester-glass mixed woven tape for outer protection and insulation.
This composite transposition structure effectively eliminates skin effect and proximity effect, reducing eddy current loss by 25%–32% compared with solid flat aluminum strips. The integrated film and paper insulation system features excellent high voltage resistance, moisture resistance and long-term thermal aging performance. Adopting aluminum as the base material cuts total winding cost by 40%–55% and reduces equipment weight by nearly 30% compared with copper transposed cable.
The whole production line is equipped with high-precision transposition and constant tension wrapping equipment. The production process adopts full digital management to realize full traceability of parameters for each production batch.
Core Technical Specification Table
|
Parameter |
Precise Technical Data |
|
Base Conductor |
Self-produced 1350 grade ≥99.7% bare aluminum wire (round & flat available) |
|
Single Round Bare Aluminum Wire Diameter |
0.8mm – 5.0mm |
|
Flat Bare Aluminum Wire Size |
Thickness: 0.7–10mm; Width: 3–38mm |
|
20℃ Resistivity of Bare Aluminum |
≤0.0280 Ω·mm²/m |
|
Bare Aluminum Temper |
Soft / Half-Hard (Customizable) |
|
Single Strand Insulation Film |
Option1: PET Polyester Film (Class B 130℃ / F155℃) |
|
Composite Structure Types |
1. Step-size composite: 2–3 different wire diameters integrated into one transposed bundle |
|
Total Strand Quantity Range |
10–42 aluminum strands (custom odd/even count) |
|
Minimum Transposition Pitch |
35mm, transposition tolerance ±0.1mm |
|
Outer Wrapping Insulation Options |
DK Composite Insulation Paper, DM Composite Insulation Paper, Glass Cloth Tape, Polyester-glass Mixed Woven Tape |
|
Max Overall Bundle Dimension |
Height ≤120mm, Width ≤26mm (tolerance ±0.05mm) |
|
Thermal Class Rating |
B(130℃) / F(155℃) / H(180℃) |
|
Executive Standards |
GB/T 19844, IEC 60317 series, GB/T5584.3, ASTM B232, customer signed technical agreement |
|
Joint-Free Continuous Length |
Up to 3500 meters for regular composite structures |
Key Product Advantages
1. Reliable Self-Supplied Bare Aluminum Raw Material
We own independent bare aluminum wire production workshop, equipped with automatic continuous extruder, multi-unit wire drawing machine and automatic annealing furnace. The whole production process is fully controlled. Eddy current non-destructive flaw detector conducts 100% online inspection to ensure qualified products. Our bare aluminum wire has low resistivity, smooth burr-free surface, and can perfectly match subsequent film wrapping and transposition processes, avoiding hidden defects caused by external raw materials.
2. Reliable Film Wrapping Insulation System
DuPont original PET/PI thin film is tightly wrapped on each bare aluminum strand to form uniform and gapless inter-strand insulation. Different from enameled wire, film wrapping will not produce pinholes, bubbles or cracks during bending and transposition. The outer DK/DM composite paper further improves dielectric strength and mechanical protection performance.
3. Custom Composite Layout
We provide customized structural solutions for special ultra-high voltage equipment. The design of step strands and built-in shielding wires solves the problems of uneven current distribution, partial discharge and electromagnetic interference, which cannot be satisfied by standard single-size aluminum transposed cables.
4. Ultra-Low Eddy Current Loss & High Space Utilization
Cyclic transposition enables each bare aluminum strand to evenly bear current in all cross-sectional positions. The compact rectangular structure greatly improves the slot fill factor of the coil, making the transformer core and shell more miniaturized and lightweight.
5. Outstanding Mechanical & Thermal Stability
After precision transposition and bundling, the product forms a rigid integrated structure, which can resist strong electrodynamic impact during short-circuit faults without strand displacement or insulation damage. PI film products are suitable for long-term operation at 180℃ dry environment; PET film products have excellent compatibility with mineral oil for oil-immersed equipment.
6. Significant Cost & Weight Advantage
Aluminum material is 70% lighter than copper, which greatly reduces equipment weight and transportation cost. Meanwhile, it has obvious price advantages for large-scale engineering projects.
Complete Production Process Flow (Bare Aluminum → Finished Transposed Cable)
Stage 1: Bare Aluminum Wire Manufacturing Process
- Step01 Pay-off: High-purity aluminum rod feeding
- Step02 Straightening: Shape correction of aluminum rod
- Step03 Iron brushing: Surface oxide & impurity removal
- Step04 Washing: Surface cleaning
- Step05 Rinsing: Deep decontamination
- Step06 Extrusion: 400–500℃ high-temperature extrusion into primary wire blank
- Step07 Cooling and drying: Quick cooling and moisture removal
- Step08 Meter counting: Precise length measurement
- Step09 Take-up: Bare aluminum wire spool storage for next process
Core Production & Testing Equipment for Bare Aluminum:
- Manufacturing Equipment: Automatic Continuous Extruder, Multi-Unit Wire Drawing Machine, Automatic Annealing Furnace
- Testing Equipment: Eddy Current Non-Destructive Flaw Detector
- Equipment Function: Based on electromagnetic induction principle, it realizes real-time detection of internal inclusions, air holes and surface cracks, and gives an alarm for defective products to ensure 100% qualified rate.
Stage 2: Transposed Cable Deep Processing
- Bare aluminum wire spool feeding
- Drawing: Multi-stage tungsten carbide die drawing to precise 0.8–5.0mm round wire diameter
- Annealing: 360–400℃ continuous furnace annealing to eliminate internal stress and improve bending flexibility
- Monofilament Film Wrapping: Automatic lapping machine wraps PET/PI film tightly around single bare aluminum wire
- Twisting & Transposition: Complete synchronous position conversion for composite insulated strands
- Automatic Square Pressing: Precision calendering to shape compact flat rectangular bundle
- Outer Overall Wrapping: Apply DK/DM paper, glass cloth tape and other outer insulation materials under constant tension
- Take up: Digital length metering and spool winding
- Full Performance Testing: Breakdown voltage, insulation resistance, aluminum conductivity, transposition pitch inspection
- Moisture-proof reinforced export packing
Main Application Scenarios
- 35kV ~ 1100kV Oil-Immersed Power Distribution Transformers & Grid Shunt Reactors
- Large Rectifier Transformers for Metallurgy, Electrochemical & Electroplating Industry
- Lightweight Mobile Power Station Transformers
- Dry-Type High-Temperature Industrial Distribution Transformers
- Nuclear Power Auxiliary Transformer Winders
- Our self-produced bare aluminum wire can also be used alone for overhead power lines and various electrical equipment internal wiring
Packing, Logistics & Delivery Terms
- Inner Spools: Heavy-duty solid wooden spools / reinforced tapered plastic spools (anti-bending protection for flat bundles)
- Outer Packaging: IPPC fumigated wooden export pallets, solid wooden crates, Euro standard pallets
- Protective Layer: Full moisture-proof PE film + shock-absorbing foam corner guards for irregular composite structures
- MOQ: 1 Ton
- Standard Lead Time: 3–5 weeks (custom composite tooling setup)
- Urgent priority order: 2–3 weeks
- Global Shipping: Sea freight, air freight, full-truck land transport, door-to-door delivery service worldwide
Frequently Asked Questions
Q1: Where do you source the aluminum conductor strands?
A: All aluminum conductors are self-produced in our bare aluminum wire workshop. We adopt 1350 high-purity aluminum, with full-process eddy current inspection, stable quality and controllable delivery cycle. Our bare aluminum wire can also be sold separately.
Q2: What is the difference between soft and half-hard bare aluminum wire?
A: Soft type has better flexibility for complex bending and winding; half-hard type owns higher tensile strength for high-speed production and long-distance transportation. We can recommend suitable temper according to your working conditions.
Q3: What is the difference between your film-wrapped aluminum CTC and enameled aluminum transposed cable?
A: Our product uses physical film wrapping for single bare aluminum strand insulation instead of liquid enamel baking. Film wrapping has better bending resistance, no hidden pinhole defects, and longer service life under high voltage and high temperature. Enamel coating is easy to crack under compression during transposition.
Q4: Can we customize the outer wrapping material thickness and overlap rate?
A: Fully customizable. We support adjustable layers, thickness, and overlap modes (half overlap, interlock, butt wrap) for DK paper, DM paper, glass cloth tape and polyester-glass mixed tape per customer drawings.
Q5: Can you provide DuPont original film & bare aluminum test reports?
A: Yes, every batch can supply DuPont material COA, plus SGS/TUV third-party test reports complying with IEC & GB standards.
Q6: Are small test samples available?
A: Standard specification samples are free of charge; customer only covers international courier shipping cost.
Hot Tags: Combined Flat Transposed Cable, aluminum composite transposed conductor, PET PI film wrapped aluminum CTC, 1100kV reactor winding wire, lightweight transformer aluminum wire, self-produced bare aluminum wire
Hot Tags: combined flat transposed cable, China combined flat transposed cable manufacturers, suppliers, factory, Combined Flat Transposed Cable, electrical flat cable, Flat Transposed Cable Of 42 Strands, flat twisted cable, twisted flat ribbon cable, twisted pair flat ribbon cable