Cable Structures

Armour is a mechanical-protection layer, independent of the insulation material and voltage class. Its material and geometry also affect mass, bending, terminations and electrical losses.

Steel wire armour (SWA)Round steel wires around the cable assembly

Common around multicore power and control cables; screened MV constructions can also include SWA.

Aluminium wire armour (AWA)Non-magnetic aluminium wires

Often used for single-core AC power cables to avoid the magnetic-loss issue of ordinary steel around one phase.

Steel tape armour (STA / DSTA)One or more specified layers of steel tape

A different protective geometry from wires; tensile duty and installation limits require the declared design.

Wire braid protectionInterwoven metallic wires

Mechanical braid and an electrical screening braid are not automatically the same component or duty.

Special tensile armourOne or more designed armour layers

Submarine and other special-service cables need dedicated load, fatigue, corrosion and system qualification.

Unarmoured constructionNo integral mechanical armour

Ducts, trays or other external protection may suit the route; electrical screens may still be present.

Single-core AC circuits commonly use non-magnetic armour to limit magnetic losses and heating. Armour earthing and any protective-conductor function are designed for the circuit fault duty.

Electrical screens perform different jobs in power and signal cables. In MV/HV insulation systems, semiconductive screens control the electric field; the metallic screen is a separate layer. Control and instrumentation screens address electromagnetic interference.

Semiconductive conductor / insulation screensSmooth the electrical interfaces around power-cable insulation

Not a substitute for a metallic screen, armour or an insulating layer.

Copper wire screen (CWS)Metallic wires around a screened power core

Screen area, fault duty, bonding and accessories form part of the electrical specification.

Copper tape screen (CTS)Metallic tapes around the insulated power core

Tape layout and electrical duty differ from a copper wire screen; substitution needs a design check.

Braid screenInterwoven conductive wires around a core group or assembly

Coverage, termination and frequency-dependent performance matter; a braid is not automatically armour.

Foil screen and drain wireConductive foil with a defined connection path

Used in many signal constructions; continuity and termination govern the completed screen.

Individual and overall screensScreens around pairs/triads, around the complete assembly, or both

Individual screens separate groups; an overall screen surrounds the laid-up groups.

A cable can combine electrical screens and mechanical armour. The screen arrangement follows the electrical duty, while the armour follows the route-protection requirement.

Insulation surrounds the conductor and provides the required electrical separation. The same material name can appear in different voltage designs; compound, thickness, screens and testing define the complete insulation system.

XLPE insulationCross-linked polyethylene

Used across power-cable voltage classes; XLPE alone does not establish current rating or the outer-sheath material.

PVC insulationPolyvinyl chloride compound around the conductor

Used in specified LV and control constructions; distinguish PVC insulation from a PVC outer sheath.

EPR / HEPR insulationEthylene-propylene rubber-based insulation

Used in selected power and flexible-duty designs; operating and mechanical limits follow the declared compound.

PE insulationPolyethylene insulation

Common in selected signal and other cable designs; an external PE jacket is a different layer.

Cross-linked halogen-free compoundsA defined halogen-free polymer system

Used in relevant PV and other constructions; compound and cable fire tests still need the declared scope.

Temperature limits and current ratings follow the product datasheet and installation conditions for the complete cable.

The outer sheath protects the cable from its environment. Compound selection addresses the moisture, weathering and mechanical exposure of the route.

PVC sheathPolyvinyl chloride outer protection

Flame, oil, UV and chemical performance depend on the specified compound and test evidence.

PE sheathPolyethylene outer protection

Used in many buried power designs; ordinary PE is not automatically flame-retardant or a complete water barrier.

LSZH / LSOH sheathLow-smoke, halogen-free compound system

Smoke and halogen properties require defined tests; LSZH does not itself mean circuit integrity during fire.

Rubber / elastomer sheathDeclared elastomeric protective compound

Flexing, oil, weather, abrasion and immersion suitability follow the actual cable duty and compound.

Metallic sheath or laminateA continuous metal layer or bonded laminate

May provide moisture protection and electrical functions; corrosion, bonding and joints require system design.

UV, oil, termite and immersion requirements are specified with the corresponding compound and test requirements.

The phase conductor carries load current. Conductor material, stranding and shape are separate from screen and armour material: an aluminium-conductor cable can have a copper screen, and a copper-conductor cable can have aluminium armour.

Copper conductorsPlain or tinned copper, as specified

Area, resistance, stranding and terminal compatibility define the required conductor.

Aluminium / aluminium-alloy conductorsAluminium or a specified alloy

Alloy, electrical resistance, connections and mechanical duty distinguish the construction.

Solid and stranded conductorsClass 1 solid and Class 2 stranded conductors for insulated cables

Conductor class describes the construction; it is not a blanket installation-flexibility approval.

Flexible fine-stranded conductorsClass 5 or Class 6 flexible copper conductors, where specified

Repeated movement, torsion, trailing service or drag-chain use require the complete cable to be rated for that duty.

Round, compacted and sector-shaped conductorsDifferent conductor geometries

Shape changes assembly dimensions and accessory fit; equal nominal area does not mean equal cable diameter.

Steel-reinforced bare conductorsAluminium strands around a steel strength member

The steel core in ACSR is reinforcement within the conductor, not cable armour outside insulation.

AAC, AAAC and ACSR are bare conductors for overhead lines; sheathed power cables serve underground and other insulated routes.

A three-core cable places the phase cores inside a common sheath. Three separate single-core cables allow a selected flat or trefoil layout, with different handling, bonding and support arrangements.

Single-core cableOne principal insulated power conductor per cable

Power circuits use the specified arrangement of separate cables; armour and bonding need the corresponding design.

Multicore power cableSeveral insulated power cores under a common sheath

Core count, neutral and protective-conductor arrangements must be explicit.

Three-core screened cableThree screened phase cores in one assembly

Screen layout, fillers and common outer layers distinguish it from three individual single-core cables.

Multicore control cableMultiple identified control conductors

Numbering, colour identification, protective conductor and screen arrangement follow the stated design.

Pairs, triads and grouped signalsConductors assembled into defined signal groups

Group twist, individual/overall screens and electrical characteristics are specified together.

Aerial bundled assemblyInsulated conductors assembled for overhead duty

Messenger, neutral and phase arrangements follow the utility design; ABC is not a burial-cable construction.

The notation 3 x 1 x 240 identifies three separate single-core 240 mm2 cables. Metallic-screen area is stated separately from phase-conductor area.

Conductor water blocking, screen-region blocking and radial barriers protect different moisture paths. Marine installations require a dedicated cable and accessory design.

Longitudinal screen-region blockingSwellable tapes, yarns or other specified components

Restricts water travel along the screened region after entry; it is not a radial metallic barrier.

Water-blocked conductorA specified barrier within the conductor assembly

Addresses a separate longitudinal path from the screen-region construction.

Radial laminate barrierBonded metal/polymer barrier beneath or within the sheath system

Addresses radial moisture entry; layer continuity, joints and terminations affect the completed system.

Metallic moisture sheathA defined continuous metallic sheath

Material, corrosion protection, electrical duty and accessory seals need the complete system specification.

Submarine protective systemDedicated barriers, sheath protection and armour

Water pressure, installation loads, fatigue and route conditions require a separate submarine design.

Longitudinal barriers limit water travel along the specified cable region; radial barriers reduce moisture ingress through the cable circumference. End seals protect cable lengths during storage and installation.

Fire-performance specifications address flame spread, smoke, combustion gases or circuit integrity. Fire-barrier layers are selected to support the required tested performance.

Flame-retardant constructionLimits flame propagation under the specified test

Single-cable and bunched-cable tests address different conditions.

Low-smoke constructionControls smoke under the stated test method

Low smoke is not equivalent to low halogen emissions or continued electrical operation.

Halogen-free compound systemMeets the relevant declared halogen / gas test requirements

An LSZH marking is not a universal product approval or a circuit-integrity classification.

Circuit-integrity / fire-resistant constructionMaintains the tested electrical function under specified fire conditions

Voltage, test arrangement, duration and any shock or water exposure belong to the claim.

Mica or other declared fire barrierAn additional material layer in certain designs

Its presence alone does not prove that the completed cable passes a circuit-integrity test.

IEC 60332, IEC 61034, IEC 60754 and IEC 60331 address different aspects. Only the applicable part, edition, test conditions and actual evidence establish the declared performance.