Le câble concentrique et le câble coaxial se ressemblent beaucoup, ce qui amène souvent les non professionnels à les confondre lors de l'approvisionnement, ou même supposer qu'il s'agit de noms différents pour le même produit. En fait, ce sont deux voies techniques complètement différentes:
Le câble concentrique est un câble d'alimentation, principalement utilisé pour transmettre de l'énergie électrique (Par exemple, service entrance cables under the UK BS 7870 standard). Coaxial cable is a signal/communication cable, mainly used to transmit high frequency signals (Par exemple, cable TV and antenna feeders).
Although their appearance may be similar, their internal structure, materials and physical principles are completely different. Below we break down and compare the structures of concentric cable and coaxial cable to help you distinguish them thoroughly.
Structure of Concentric Cable
The “concentric” in concentric cable means that the neutral conductor (neutral/earth) is helically wrapped concentrically around the insulated phase conductor.
- Central phase conductor: The material is usually soft annealed copper, aluminium, aluminum alloy or copper clad aluminum. It is solid or stranded and is responsible for carrying large currents.
- Couche isolante: XLPE, PVC or EPR is mainly used. It isolates the phase conductor from the outer neutral conductor.
- Concentric neutral conductor: This is usually bare copper wire or bare aluminum alloy wire, wrapped around the insulation layer in SZ helical or alternating fashion. It serves as both the neutral return path and mechanical protection.
- Filler and tape (for multicore cables): Polyester tape or filler rope is used for shaping, isolation and moisture protection.
- Gaine extérieure: The outermost layer is usually PVC, LSZH (low smoke zero halogen) or PE, and some cables have armor.
Structure of Coaxial Cable
The “coaxial” in câble coaxial means that the inner conductor, insulating dielectric and outer conductor shield share the same geometric center (axis). The signal is transmitted in the space between the inner and outer conductors.
- Chef d'orchestre intérieur (center conductor): The material is usually copper, cuivre en conserve, silver plated copper or even copper clad steel. Its diameter and material directly determine signal attenuation and characteristic impedance.
- Insulating dielectric layer: Foamed PE, solid PE or PTFE is mostly used. It not only isolates the inner and outer conductors but also fixes the spacing. The dielectric constant directly determines the impedance (50 Ω or 75 Oh).
- Outer conductor (shield): Materials include copper braid, aluminum foil plus copper braid, corrugated copper tube, etc.. It is the signal return ground and also shields external electromagnetic interference and prevents signal leakage.
- Gaine extérieure: PVC, PE or LSZH. Black weather resistant PE is commonly used outdoors, and light colors are used indoors.
Câble concentrique vs câble coaxial: How to Choose for Different Scenarios?
Types of Concentric Cable
- By core number: noyau unique (neutral wire wrapped directly outside the phase conductor) et multicore (multiple phase conductors stranded together, with neutral wire wrapped outside).
- By neutral form: split concentric (phase and neutral separated, common in UK standard service entrance cables) et concentric neutral (overall wrapping, common in US standard underground power supply).
- By voltage: basse tension (600/1000 V) has a simple structure; medium voltage (15 kV, 25 kV, etc.) requires an added semiconductive screen and semiconductive sheath.
- By standard: CEI 60502-1, BS 7870, ASTM B881, etc., with strict requirements on wrapping method and dimensions.
Types de câbles coaxiaux
- By characteristic impedance: 50 Oh (communication, RF, antenna feeders) et 75 Oh (cable TV, video surveillance).
- By shielding strength: single braid (basic), aluminum foil plus braid double shield (mainstream surveillance), multilayer shield (high interference resistance) and corrugated copper tube (fully shielded RF).
- By insulating dielectric: foamed PE (faible perte) and PTFE (high temperature and high frequency resistance).
Comparison of Concentric Cable and Coaxial Cable
To help engineers and procurement staff check quickly, here is a direct comparison of concentric cable and coaxial cable:
| Dimension | Concentric Cable | Câble coaxial |
|---|---|---|
| Core function | Transmit power | Transmit signal / RF |
| Structural logic | Phase conductor inside, neutral conductor concentrically wrapped outside | Chef d'orchestre intérieur, insulation and outer shield share the same axis |
| Function of outer conductor | Serves as neutral (N) or earth (PE) return path, with protective function | Serves as signal return ground, with electromagnetic shielding function |
| Parameters | Cross sectional area, ampacity, tension nominale | Characteristic impedance (50/75 Oh), shielding attenuation |
| Applications | Service entrance power lines, low voltage distribution networks, street lighting | Télévision par câble, video surveillance, antennas, RF communication |
Installation Environment and Construction Constraints
Concentric cables and coaxial cables have vastly different requirements for their installation environments; incorrect placement or improper handling can lead to immediate failure:
Câbles concentriques (Distribution d'énergie):
Primarily used for direct underground burial, building service entrances, or outdoor conduits. Construction constraints: The outer layer of bare copper neutral wires is susceptible to damage during pulling; if the outer sheath is compromised, the cable becomes highly vulnerable to moisture and corrosion once buried. Rough handling or forceful pulling is strictly prohibited; an adequate bending radius must be maintained.
Câbles coaxiaux (Signal Transmission):
Primarily used in indoor low-voltage cable trays, on surveillance poles, or for outdoor antennas. Construction constraints: The internal foamed insulation layer is extremely sensitive to pressure. Sharp bends or “kinks” at corners can cause impedance fluctuations and signal loss. En outre, outdoor connectors must be rendered strictly watertight; the ingress of water will effectively destroy the high-frequency signal.
Conclusion
Câble concentrique is designed to deliver “power” safely and economically to homes and businesses; coaxial cable is designed to deliver “signals” to terminals cleanly and with interference resistance. The two cannot replace each other and cannot be mixed. In overseas projects, whether for power distribution or communication surveillance, ZMS Cable can provide high quality cables that meet international standards.
We provide concentric cables compliant with BS 7870 et CEI 60502, as well as various 50 Ω/75 Ω coaxial cables (such as the RG series), meeting full scenario requirements from power to signal. En outre, the ZMS Cable engineering team will recommend the correct model strictly according to your application scenario (power supply circuit or low voltage signal), avoiding project rework caused by selection errors.
Need to purchase concentric cable or coaxial cable for your project? Please send your specification requirements to our technical team, and we will provide an accurate quotation and technical support.