FAQ
Frequently Asked Questions (FAQ) on Special Cables
1. What are the common types of special cables?
Common types include: high-temperature cables (resistant to -60°C to 200°C+), flame-retardant cables (low smoke zero halogen, flame retardant grades V0/V1), shielded cables (anti-EMI/RFI), waterproof cables (IP67/IP68), explosion-proof cables (spark-resistant/corrosion-resistant), drag chain cables (flexible/abrasion-resistant), low smoke zero halogen cables (low toxicity/low smoke), nuclear fusion cables, etc.
2. What are the core differences between special cables and ordinary cables?
- Performance: Special cables have special properties such as resistance to extreme environments (high temperature, corrosion, strong electromagnetic fields, nuclear fusion), and high safety (flame retardant, low toxicity); ordinary cables only meet the requirements of conventional electrical transmission.
- Materials: Special cables use special materials such as fluoroplastics, silicone rubber, tin-plated copper, etc.; ordinary cables are mostly made of PVC and polyethylene.
- Applications: Special cables are used in industrial, new energy, aerospace, underwater, submarine, wind power generation, nuclear fusion and other harsh environments; ordinary cables are only suitable for buildings, homes and other conventional environments.
3. What is the temperature range and application scenarios of high-temperature cables?
The temperature range is usually -60°C to 200°C (silicone rubber material) or -200°C to 300°C (fluoroplastic material), and they are suitable for high-temperature environments such as metallurgy, kilns, and new energy battery compartments.
4. What are the core advantages of low smoke zero halogen cables?
When burning, they release low smoke (transmittance ≥ 60%) and no halogen (Cl⁻/Br⁻ content < 50mg/kg), reducing toxicity and corrosive gases, and lowering the risk of casualties and equipment damage. They are suitable for places with dense populations such as subways, hospitals, and high-rise buildings.
5. How to judge the quality of special cables?
- Materials: Insulation layer thickness meets the standard (±0.1mm), shielding coverage ≥ 85% (braided shielding);
- Test reports: Temperature cycling (-40°C to 150°C 1000 times without cracking), insulation resistance (≥ 100MΩ·km);
- Appearance: Clear markings (model/specification/certification), no bulges or scratches.
- Certification: Whether it has passed authoritative certifications such as UL (USA), CE (EU), CCC (China), etc.
6. When high-speed data cables transmit at 10Gbps or above, signal jitter occurs. What could be the reasons and how to solve it?
The possible reasons are: ① The dielectric loss tangent (tanδ) is too large (dielectric polarization loss increases at high frequencies); ② The conductor twisting is uneven, causing the characteristic impedance (Z0) to fluctuate (the standard requires Z0 = 100 ± 5Ω); ③ The shielding coverage is insufficient (electromagnetic coupling interference increases when it is less than 95%). Solutions include: using FEP or foamed PE low-loss dielectric (tanδ < 0.001@1GHz), adopting precise twisting technology (pitch error ≤ ±2%), double-layer shielding (aluminum foil + tin-plated copper mesh, coverage ≥ 98%), and calibrating impedance consistency through a vector network analyzer (VNA).
7. When the phase change of a stable phase low-loss cable exceeds ±30°/m during temperature cycling (-40°C to 85°C) testing, how to improve phase stability?
The key lies in the matching of materials and structures:
① Use dielectric materials with low CTE (coefficient of thermal expansion) (such as PTFE CTE = 100×10⁻⁶/°C, adding ceramic micro-powder can reduce it to 50×10⁻⁶/°C);
② Use Invar (Ni36) or titanium alloy (CTE ≈ 1.2×10⁻⁶/°C) for the inner conductor to form a thermal matching structure with the outer conductor (silver-plated copper tube);
③ Use spiral winding shielding (instead of direct welding shielding) to reduce stress concentration during temperature deformation. The test requires real-time monitoring of phase drift through a high and low temperature chamber and a network analyzer.
8. After vibration testing (10~2000Hz, acceleration 20g), high-performance transmission wires for aerospace applications experienced core breakage. What are the causes and improvement plans?
Causes:
① The diameter of the single wire of the conductor is too large (>0.2mm), resulting in insufficient flexibility;
② The adhesion between the insulation layer and the conductor is too strong (without a buffer layer), causing concentrated shear stress during vibration.
Improvement plan: Use 7×37 strands of fine copper wire (single wire diameter 0.08mm) for the conductor (elongation at break ≥30%), and extrude a 0.05mm thick polyimide film buffer layer outside the conductor.
The insulation should be made of vibration-resistant fluororubber (Shore A hardness 60±5), and pass the IEC 60068-2-6 vibration test (no core breakage for 8 hours at 2000Hz).
9. How to eliminate electromagnetic interference in medical imaging equipment (such as MRI) cables in strong magnetic fields (3T) that cause image artifacts?
A "full shielding + magnetic isolation" design should be adopted:
① Use silver-plated copper tape (overlap ≥90%) for inner shielding and high-permeability permalloy tape (μ≥8000) for outer shielding to form a magnetic shielding cavity;
② Use twisted-pair cable structure (pitch 5~10mm) to reduce loop area (≤0.1cm²) and decrease magnetic flux coupling;
③ Use non-magnetic materials (titanium alloy shell) for the connectors at both ends to avoid eddy currents;
④ Use "multi-point grounding" for the shielding layer (interval ≤1m), with grounding resistance ≤0.5Ω. S-parameter testing (S21<-80dB@1MHz) should be conducted to ensure shielding effectiveness.
10. How to select the type of oil-resistant cable for CNC machine tools when the insulation layer swelling rate exceeds 20% after long-term contact with cutting oil (containing mineral oil and esters)?
Selection should be based on the type of oil:
① For mineral oil environments, choose chloroprene rubber (CR) insulation (swelling rate ≤15%, meeting IEC 60811-2-1 standards);
② For ester/synthetic oil environments, choose hydrogenated nitrile rubber (HNBR) or perfluoroelastomer (FFKM) (swelling rate ≤8%);
③ For high-temperature (＞120℃) oil environments, choose cross-linked polyethylene (XLPE) insulation (temperature resistance grade 150℃, with better anti-aging performance than rubber). When selecting, an oil sample composition report should be provided, and a third party should conduct an immersion test (70℃×168h) for verification.
11. What are the application scenarios of nuclear fusion cables?
Nuclear fusion cables are a key technology supporting the operation of controllable nuclear fusion devices, mainly used in power transmission and magnetic confinement systems of fusion devices. They can be further classified into superconducting cables and high-temperature superconducting cables. For example, TF (toroidal field) and PF (poloidal field) superconducting cables in tokamak devices provide stable power transmission for strong magnetic field confinement. In fusion power generation systems, they achieve efficient energy transmission from fusion reactors to the power grid, reducing losses and improving energy utilization efficiency.
12. How to improve the radiation resistance of nuclear fusion cables when the insulation layer becomes brittle and cracks under neutron radiation (flux 10¹⁴n/cm²·s)?
A: The key lies in material modification and structural enhancement:
① Use irradiation cross-linked polyethylene (XLPE) + mica tape composite layer (mica content ≥95%, pre-cross-linked by γ-rays, radiation resistance ≥2000kGy) for insulation;
② Use nickel-based alloys (such as Inconel 600) for the conductor, with a nickel coating (thickness 5μm) on the surface to prevent high-temperature oxidation;
③ Use polyetheretherketone (PEEK) (Tg=143℃, elongation at break ≥40%, strength retention rate after radiation ≥80%) for the sheath. After cobalt source irradiation testing (1000kGy), test the insulation resistance (≥500MΩ·km) and tensile properties (strength retention rate ≥70%).
13. What are the differences between water-resistant cables and submarine cables?
Waterproof cables: Special cables that can operate in damp, submerged or deep-sea high-pressure conditions. They have advantages such as good waterproof sealing, corrosion resistance, excellent electrical transmission stability, and resistance to electromagnetic interference. They are typically composed of three parts: conductors, sheaths, and insulation layers. They can provide power supply and signal control for underwater robots and have broad application prospects in underwater communication, underwater oil and gas exploration, marine observation, and many other fields. Submarine cables: Mainly used for power transmission or communication connections in underwater environments such as the sea, rivers, and lakes. According to their uses, they can be classified as power cables, communication cables, or optical-electrical composite cables. Their structures and performances need to meet the requirements of long-distance laying, deep-sea high pressure, and large-capacity transmission. Summary: The application scenarios and design requirements of the two are different.
14. How to optimize the sealing structure of the waterproof cable for the ROV after repeated retraction and extension, when water leakage occurs (insulation resistance < 100MΩ)?
A: It is necessary to strengthen the "radial + axial" dual sealing:
① Radial sealing: Extrude hot melt adhesive (melting point 80~100℃) between the insulation layer and the inner sheath, and wrap semiconductive water-blocking tape (expansion rate ≥ 300% when exposed to water);
② Axial sealing: Fill the conductor twisting gap with butyl rubber sealing paste (viscosity 50000~80000mPa·s), and after the cable core is formed, wrap steel tape armor (lap rate ≥ 25%);
③ Dynamic sealing: Use a combination of "O-ring (fluorine rubber) + wedge-shaped sealing part" at the connector, with a compression rate controlled at 20%~30%. It needs to pass the immersion test (1000m water depth × 24h) and have an insulation resistance ≥ 500MΩ.
15. How does the structural design of submarine cables deal with deep-sea high pressure and corrosive environments?
Adopt a "layered protection" structure:
① Conductor: High-purity oxygen-free copper (OFHC) or aluminum alloy, ensuring low resistance and corrosion resistance;
② Insulation layer: High-density polyethylene (HDPE) or cross-linked polyethylene (XLPE), water pressure resistance > 100MPa (corresponding to 10000m deep sea);
③ Shielding layer: Lead alloy sheath (preventing seawater penetration) + copper tape winding (preventing electrochemical corrosion);
④ Buffer layer: Asphalt + polypropylene rope, absorbing mechanical shock during laying;
⑤ Armor layer: Double-layer galvanized steel wire (shallow sea) or stainless steel tape (deep sea), tensile strength > 2000N/mm²;
⑥ Outer sheath: High-density polypropylene (PP), resistant to marine organism attachment and UV aging.
16. How to precisely control the buoyancy deviation of the zero-buoyancy cable for underwater robots when it exceeds ±5% (design buoyancy 0kg/m) during operation?
Through the "material density + structural cavity" coordinated control:
① Use low-density polyethylene (LDPE) foamed sheath (density 0.7~0.9g/cm³, foaming ratio 30%~50%, control density by adjusting nitrogen injection volume);
② Embed hollow microspheres (glass microspheres, density 0.2g/cm³, volume ratio 15%~20%) in the cable core;
③ Calculation formula: Buoyancy (kg/m) = (sheath volume + cavity volume) × 1 (water density) - total cable mass (kg/m). By adjusting the foaming ratio and microsphere content, the buoyancy can be controlled within ±3%. Stability needs to be verified through a suspension test in a water tank (24h).
17. What information does the customer need to provide for custom special cables?
The customer needs to provide:
① Application scenarios (such as aircraft engine compartments / deep-sea exploration equipment);
② Electrical parameters (rated voltage (AC/DC), current, signal type (analog/digital), impedance, transmission frequency);
③ Environmental parameters (temperature range, humidity, corrosive media (oil/chemical corrosion), electromagnetic interference intensity);
④ Mechanical performance (bending radius (static/dynamic), wear resistance, tensile strength).
⑤ Structural requirements (conductor strand count/diameter, insulation/sheath material grade, shielding method (braided/wrapped/foil), color/printing, minimum bending radius);
⑥ Installation method: fixed installation/moving drag chain, buried/overhead/submerged;
⑦ Certification requirements (whether it complies with UL/CE/CCC/EN and other industry standards);
⑧ Test standards (such as withstand voltage test, insulation resistance test, burning test).
18. When customizing deep-sea exploration cables, if the customer only provides the requirement of "water pressure resistance at 6000 meters", how to refine the technical parameters?
Key parameters to be supplemented:
① Electrical performance (rated voltage AC 3kV/DC 5kV, insulation resistance ≥ 100MΩ·km);
② Mechanical performance (dynamic tensile strength ≥ 50kN, bending life ≥ 10⁴ times @ bending radius 10×OD);
③ Environmental parameters (operating temperature -20~60℃, seawater salinity 3.5%, resistance to microbial corrosion);
④ Special functions (whether integrated with optical fiber sensing, buoyancy adjustment requirements). It is recommended to provide the equipment operation depth curve (including instantaneous impact pressure), and design the armor layer according to API 17E standard (316L stainless steel wire, diameter 3mm, Z-type lock armor structure).
19. What are the main factors affecting the delivery time of special cables? How to shorten the delivery time?
Main factors:
① Material procurement cycle (special materials such as polyimide film need 4~6 weeks);
② Process complexity (such as laser stripping, multi-core stranding requires custom tooling);
③ Test items (such as high and low temperature cycling test needs 1~2 weeks).
Measures to shorten the delivery time:
① Lock in the inventory of commonly used materials in advance (such as copper conductors, conventional insulation materials);
② Adopt modular design (such as standardized shielding structure);
③ Conduct sample testing and material procurement in parallel (after customer confirmation of the plan);
④ Simplify non-critical tests (such as conventional performance that has been verified by the customer can be exempted from inspection).
20. When the standing wave ratio (VSWR) of a radio frequency coaxial cable (such as RG-402) exceeds the standard (>1.2@18GHz) during production, how to identify process defects?
Key inspection points:
① Inner conductor roundness (Z0 fluctuation when tolerance > ±0.01mm), online monitoring with a laser micrometer (roundness ≤ 0.005mm);
② Insulation medium concentricity (uneven field strength distribution when eccentricity > 5%), adjust the concentricity of the extrusion die (error ≤ 2%);
③ Outer conductor welding quality (impedance mutation due to false welding), use argon arc welding (welding current 8~12A, speed 15~20m/min), and conduct eddy current testing after welding;
④ Cable laying tension fluctuation (causing insulation layer stretching deformation), use a constant tension control system (tension fluctuation ≤ ±2%). After debugging, conduct VSWR sweep tests across the entire frequency range (0.1~26.5GHz) using a network analyzer (8753ES).
21. When laying polytetrafluoroethylene (PTFE) insulated cables in a low-temperature environment (-40℃), insulation cracking occurs. How to avoid it?
Pre-treatment before installation:
① Preheat the cable (using a hot air gun, temperature 50~60℃, for 10~15 minutes, avoiding local overheating);
② The minimum bending radius during laying should be ≥ 10 times the cable outer diameter (static laying) or 15 times (dynamic laying), and "dead bends" (bending angle > 90°) are prohibited;
③ Use toothless cable pulleys (to avoid scratching the insulation), and control the traction force within 15% of the conductor breaking strength. If cracking has occurred, the damaged section should be cut off and a new joint made (using an expansion-type connector to avoid insulation stress during tightening).
22. Can samples be produced, and are they free?
We can provide samples. If the product value is small, we can send samples for free; if the product value is high, producing samples also incurs significant costs, so samples will need to be paid for.