"I will provide you with a comprehensive and in-depth analysis of EV low-smoke zero-halogen wires, covering their definition, structure, execution standards, performance parameters, and quality identification methods."

（Quality Leader of TRIUMPH CABLE Industrial Cables  Gao Mingfu）

This article aims to provide purchasing personnel, engineers, and technicians in relevant industries with a systematic and professional knowledge system regarding EV low-smoke zero-halogen wires, assisting industry professionals in making scientific decisions throughout the entire process, from material selection to project implementation. As the third-generation environmentally friendly cable technology, EV low-smoke zero-halogen wires, with their core characteristics of "low smoke, zero halogen, and flame retardancy," have become mandatory standards in high-end fields such as new energy vehicles and energy storage. This article will systematically introduce their definition, structure, performance, and identification methods, providing references for industry applications.

I. Introduction

EV low-smoke zero-halogen wires are environmentally friendly insulated conductors specifically designed for new energy vehicles and electric transportation equipment. Their core advantage lies in the insulation layer material, which does not contain halogens, ensuring that no toxic gases are released and the smoke concentration is extremely low during combustion from the material source. Through special processing techniques, these products achieve the unification of three key performance characteristics: flame retardancy, low smoke, and zero halogen. In high-risk scenarios such as new energy vehicle battery systems and motor controllers, they can buy precious time for personnel evacuation and effectively reduce the risk of equipment damage in the event of accidents.

II. Definition and Naming Rules of EV Low-Smoke Zero-Halogen Wires

• Core Definition: Refers to environmentally friendly wires that do not contain halogens (F, Cl, Br, etc.) and environmentally harmful substances such as lead and cadmium, and do not release toxic smoke during combustion. Their halogen content must be ≤50 PPM, hydrogen halide gas after combustion <100 PPM, and light transmittance ≥60%, meeting international standards such as PREN 14582 and EN 5067-2-1.
• Naming Rules: In China, they are usually prefixed with "WDZ" (halogen-free, low-smoke, flame-retardant), such as WDZ-RYY flexible cables. In EU standards, the "Halogen-free" label is commonly used, and in the automotive industry, they may include the "EV" specific application code.

III. Structural Characteristics of EV Low-Smoke Zero-Halogen Wires

3.1 Conductor Structure

The conductor of EV low-smoke zero-halogen wires is the core carrier for current transmission, and its structural design must balance electrical conductivity with the mechanical requirements of vehicle wiring: High-purity oxygen-free copper (purity ≥99.97%) is mainly used, and in some high-end scenarios, tin-plated copper or silver-plated copper is used to enhance corrosion resistance and oxidation resistance, meeting the long-term high-load operation requirements of EVs.

3.2 Insulation Layer

The insulation layer of EV low-smoke zero-halogen wires mainly uses XLPE (cross-linked polyethylene) material. By chemically or physically forming a three-dimensional network structure of polyethylene molecules, its heat resistance, mechanical strength, and insulation performance are significantly improved. It can typically withstand 105°C (e.g., UL 3385 series), and some high-voltage models can reach 125°C (e.g., EV high-voltage connecting wires). XLPO (cross-linked polyolefin) is an improved version of XLPE, with better flexibility and stronger weather resistance, commonly used in extreme environments such as ships and rail transit.

3.3 Shielding Layer

The shielding layer design of EV low-smoke zero-halogen wires is divided into two categories based on whether electromagnetic interference (EMC) resistance is required, directly affecting the stability of vehicle electronic systems.

3.3.1 Shielded Structure

• Structural Forms:
  • Copper Wire Braided Shielding: With a coverage rate of ≥80%, it has bidirectional electromagnetic shielding capabilities (suppressing signal leakage internally and resisting external interference externally), suitable for high-precision signal transmission in vehicle-mounted radars and autonomous driving sensors.
  • Aluminum Foil + Copper Wire Composite Shielding: Aluminum foil provides full-包裹性 (enveloping) shielding, and copper wire enhances mechanical strength, increasing EMC interference attenuation to 40-60 dB, meeting the ISO 11452 electromagnetic compatibility standard.
• Mechanical Protection: The shielding layer can buffer external compression and friction damage to the insulation layer, increasing the cable's service life by 20%-30%.
• Grounding Function: By grounding the shielding layer, static electricity can be quickly discharged (static decay time <1s), avoiding sparks that could ignite low-smoke zero-halogen materials.

3.3.2 Unshielded Structure

• Performance Characteristics:
  • Without the shielding layer, the weight is reduced by 15%-20%, and the cost is reduced by 10%-15%, suitable for vehicle-mounted low-voltage lighting and non-precision control circuits (e.g., window lift motors).
• Limitations: It lacks electromagnetic shielding capabilities and is susceptible to external EMC interference (e.g., high-frequency noise generated by motors and inverters), which may lead to an increase in signal transmission error rates. Its resistance to mechanical damage is weaker and requires additional pipe protection for installation.

3.4 Key Processes

• Irradiation Cross-linking Technology: By modifying with high-energy electron beams, a three-dimensional network structure of molecular chains is formed, increasing the tensile strength to above 1.2 Kgf/mm², superior to traditional PVC wires (1.05 Kgf/mm²).
• Water Blocking Design: A water-blocking layer is added between the insulation layer and the sheath, suitable for high-humidity environments such as EV battery packs.

IV. Core Performance Parameter Indicators

4.1 Electrical Performance

• Rated Voltage: Three levels of 600V/1000V/1500V, with 1500V being the most commonly selected for new energy vehicle high-voltage systems.
• Insulation Resistance: ≥100 MΩ·km under normal conditions and ≥10 MΩ·km after immersion in water.
• Breakdown Strength: ≥25 kV/mm (at 20°C).

4.2 Environmental Adaptability Parameters

4.3 Flame Retardancy Test

• Test Conditions:
  • Prepare 5 test specimens with an insulated length of at least 600 mm.
  • Use a Bunsen burner filled with appropriate combustible gas as the test device, with a combustion tube inner diameter of 9 mm and an internal blue conical flame temperature of (950 ± 50)°C.
• Judgment Criteria:
  • All combustion flames on the insulating material should extinguish within 70 seconds.
  • At least 50 mm of insulation at the end of the specimen should remain unburned.

• Test Method:

  • The specimen should be kept at a 45° ± 1° angle to the vertical axis, with a minimum distance of 100 mm from any end of the specimen to the combustion chamber wall. Apply the flame at a distance of (500 ± 5) mm from the upper end of the insulation. After 30 seconds, the flame can be removed.

  
  

  
  

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V. Application Areas

• New Energy Vehicles: Battery pack connecting wires and motor control wires, meeting the wide temperature range requirements of -40°C to 125°C.
• Rail Transit: Metro carriage wiring, passing the stringent requirement of a flame spread speed ≤1.5 m/s in the EN 50399 standard.
• High-End Electronics: Internal wiring for drones and charging stations, adapting to installations with small bending radii (e.g., bending radius <5 times the cable diameter).
• Construction Engineering: In personnel-dense places such as hospitals and data centers, replacing traditional PVC wires to reduce secondary disaster risks.

VI. Quality Identification Methods

1. Label Verification: The surface must be clearly labeled with relevant parameters, model specifications, and company name, and the printed text should be difficult to erase.
2. Flexibility Check: Bend the cable 50 times without cracks. High-quality products can withstand a bending test with a diameter 10 times that of the cable.
3. Professional Testing: The manufacturer should provide relevant test reports (e.g., raw material production, specification sheets, flame retardancy tests, halogen content test reports, etc.).

VII. Conclusion

EV low-smoke zero-halogen wires have established a technological advantage of "safety-environmental protection-durability" through the innovative integration of material science and structural engineering. Purchasing personnel need to focus on material certifications (such as UL 94 V-0, IEC 60332-3-24) and scenario adaptability, while engineers should establish a triangular evaluation model of "parameters-performance-cost." With the intensification of policies such as the EU's "New Battery Regulation" (to be implemented in 2027), halogen-free will become an irreversible technological direction in the cable industry. It is recommended that relevant enterprises proactively deploy irradiation cross-linking production lines and research and development of bio-based materials to seize the high ground in the new energy industry.