{"id":31134,"date":"2026-10-08T07:03:52","date_gmt":"2026-10-08T07:03:52","guid":{"rendered":"https:\/\/doingcable.com\/?p=31134"},"modified":"2026-10-08T07:03:54","modified_gmt":"2026-10-08T07:03:54","slug":"what-is-a-triple-layer-co-extrusion-dry-cure-ccv-line","status":"publish","type":"post","link":"https:\/\/doingcable.com\/fr\/what-is-a-triple-layer-co-extrusion-dry-cure-ccv-line\/","title":{"rendered":"What Is a Triple Layer Co-Extrusion Dry Cure CCV Line?"},"content":{"rendered":"

A Ligne CCV \u00e0 coextrusion triple couche et vulcanisation \u00e0 sec<\/strong> is a continuous catenary vulcanization system that simultaneously extrudes the conductor screen, XLPE insulation and insulation screen through a single triple crosshead, then cross-links the peroxide-cured XLPE inside a pressurized nitrogen-filled heated tube.<\/p>\n\n\n\n

It is the global standard process for medium-voltage (6\u201335 kV) and high-voltage (up to 110\u2013132 kV, extendable higher) XLPE power cables. Dry nitrogen cure eliminates the residual moisture associated with steam curing and thereby reduces water-tree risk. True triple co-extrusion eliminates interface contamination between the three layers.<\/p>\n\n\n\n

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inquiry now<\/a><\/div>\n<\/div>\n\n\n\n

Typical configurations cover Cu 25\u20131000 mm\u00b2 \/ Al 35\u20131000 mm\u00b2, insulation thickness 3.4\u201315 mm (higher for EHV), line speeds 0\u201330 m\/min, and half-catenary or vertical layouts. Finished cores must meet IEC 60502-2 or IEC 60840 after degassing and subsequent screening\/sheathing.<\/p>\n\n\n\n

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What Is a Triple Layer Co-Extrusion Dry Cure CCV Line?<\/h1>\n\n\n\n

A Ligne CCV \u00e0 coextrusion triple couche et vulcanisation \u00e0 sec<\/strong> produces the insulated core of XLPE power cables by extruding three layers in one pass and continuously cross-linking the insulation under pressurized dry nitrogen in a catenary tube.<\/p>\n\n\n\n

CCV = Continuous Catenary Vulcanization. The cable hangs under gravity in a natural catenary curve inside a long stainless-steel tube. Dry cure means the vulcanizing medium is high-purity nitrogen (normally \u226599.5 %) rather than saturated steam. The combination of true triple co-extrusion and dry nitrogen cure became the industry standard for peroxide-cured XLPE after water-tree failures were linked to residual moisture from steam curing.<\/p>\n\n\n\n

How does the triple-layer dry-cure CCV process actually work?<\/h2>\n\n\n\n

The conductor is paid off, optionally preheated, and enters a precision triple crosshead. Three dedicated extruders simultaneously apply the inner semi-conductive screen, XLPE insulation and outer semi-conductive screen. The coated core immediately enters the heated catenary tube where radiant heat and pressurized nitrogen raise the insulation temperature so that the organic peroxide decomposes and forms cross-links.<\/p>\n\n\n\n

Typical process sequence and control points:<\/p>\n\n\n\n

    \n
  1. Pay-off, dancer or accumulator, optional conductor preheater (improves heat transfer into the insulation and reduces droop).<\/li>\n\n\n\n
  2. Triple co-extrusion through a dedicated three-layer crosshead (common sizes \u03a665\/150\/90 for MV, \u03a680\/175\/100 for higher output\/HV).<\/li>\n\n\n\n
  3. Entry heat treatment zone (sometimes used to control viscosity near the conductor).<\/li>\n\n\n\n
  4. Heating section of the CCV tube (multiple independent zones, tube wall temperatures typically 300\u2013450 \u00b0C, design often 400\u2013450 \u00b0C).<\/li>\n\n\n\n
  5. Transition \/ pre-cooling zone (still under nitrogen pressure).<\/li>\n\n\n\n
  6. Pressurized water-cooling section.<\/li>\n\n\n\n
  7. Exit seal, haul-off, inline X-ray or laser measurement of diameter and eccentricity, take-up.<\/li>\n<\/ol>\n\n\n\n

    Nitrogen pressure is normally maintained at approximately 1.0\u20131.6 MPa (design pressure of tubes commonly 1.6 MPa, supply pressure 2.0\u20132.5 MPa). The pressure keeps cross-linking by-products (including methane) in solution and suppresses void formation. Residence time in the heating section is set by line speed and tube length so that cross-link density reaches the required level (normally verified by hot-set test) throughout the insulation wall.<\/p>\n\n\n\n

    How do dry-cure CCV, steam CCV and moisture-cure processes compare?<\/h2>\n\n\n\n

    Dry-cure nitrogen CCV is preferred for XLPE MV\/HV. Steam CCV remains common for rubber. Moisture-cure (silane) is used mainly for low-voltage XLPE.<\/p>\n\n\n\n

    Process<\/th>Medium<\/th>Typical voltage<\/th>Moisture risk<\/th>Layer structure<\/th>Notes<\/th><\/tr><\/thead>
    Dry-cure CCV (N\u2082)<\/td>Pressurized nitrogen + radiant heat<\/td>6\u2013132 kV (extendable)<\/td>Tr\u00e8s bas<\/td>True triple co-extrusion<\/td>Standard for peroxide XLPE<\/td><\/tr>
    Steam CCV<\/td>Saturated steam<\/td>Rubber \/ some EPR<\/td>High (water-tree risk)<\/td>Single or dual<\/td>Still used for elastomers<\/td><\/tr>
    Moisture-cure (Sioplas)<\/td>Water after extrusion<\/td>Mainly LV<\/td>Controlled<\/td>Usually single\/dual<\/td>Not for MV\/HV peroxide<\/td><\/tr>
    VCV \/ MDCV<\/td>Nitrogen or oil<\/td>EHV \/ thick walls<\/td>Faible<\/td>Triple<\/td>Vertical or special geometry for thick insulation<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

    Dry-cure\u2013dry-cool variants (nitrogen also used for cooling) further reduce residual moisture for HV\/EHV cables.<\/p>\n\n\n\n

    What are the detailed technical parameters of typical MV and HV CCV lines?<\/h2>\n\n\n\n
    Param\u00e8tre<\/th>6\u201335 kV MV (6-section)<\/th>6\u201335 kV MV (9-section)<\/th>10\u2013110 kV HV<\/th><\/tr><\/thead>
    Voltage class<\/td>6\u201335 kV XLPE<\/td>6\u201335 kV XLPE<\/td>10\u2013110 kV XLPE<\/td><\/tr>
    Conductor<\/td>Cu 25\u2013630 \/ Al 35\u2013800 mm\u00b2<\/td>Same<\/td>Cu 25\u20131000 \/ Al 35\u20131000 mm\u00b2<\/td><\/tr>
    Max cable \u00d8<\/td>~70 mm<\/td>~70 mm<\/td>~80 mm<\/td><\/tr>
    Max weight<\/td>~10 kg\/m<\/td>~10 kg\/m<\/td>~14.5 kg\/m<\/td><\/tr>
    Conductor screen<\/td>0.5\u20132.0 mm<\/td>0.5\u20132.0 mm<\/td>0.5\u20132.0 mm<\/td><\/tr>
    Insulation<\/td>3.4\u201312 mm<\/td>3.4\u201312 mm<\/td>3.4\u201315 mm<\/td><\/tr>
    Insulation screen<\/td>0.5\u20132.0 mm<\/td>0.5\u20132.0 mm<\/td>0.5\u20132.0 mm<\/td><\/tr>
    Line speed<\/td>0\u201330 m\/min<\/td>0\u201330 m\/min<\/td>0\u201325 \/ 0\u201330 m\/min<\/td><\/tr>
    Heating section<\/td>\u224841 m (6 tubes)<\/td>\u224854 m (9 tubes)<\/td>\u224854 m (9 tubes)<\/td><\/tr>
    Pre-cooling<\/td>12 m (2 tubes)<\/td>12 m<\/td>12 m<\/td><\/tr>
    Cooling section<\/td>\u224854 m (9 tubes)<\/td>\u224890 m (15 tubes)<\/td>\u224884 m (14 tubes)<\/td><\/tr>
    Extruders<\/td>\u03a665 \/ 150 \/ 90<\/td>\u03a680 \/ 175 \/ 100 (optional)<\/td>\u03a680 \/ 175 \/ 100<\/td><\/tr>
    Installed power<\/td>~750 kVA<\/td>~1050 kVA<\/td>~1000 kVA<\/td><\/tr>
    Nitrogen<\/td>2.0\u20132.5 MPa supply, \u226599.5 %<\/td>Same<\/td>Same<\/td><\/tr>
    Tube material<\/td>SS 304<\/td>SS 304<\/td>SS 304<\/td><\/tr>
    Design pressure<\/td>1.6 MPa<\/td>1.6 MPa<\/td>1.6 MPa<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

    Higher-output or EHV packages use longer heating sections, larger extruders, steeper catenary angles or vertical U-shape geometry, and advanced sag-control systems.<\/p>\n\n\n\n

    Which standards, compounds and process controls are mandatory?<\/h2>\n\n\n\n

    Finished cables must comply with IEC 60502-2 (6\u201330 kV) or IEC 60840 (30\u2013150 kV). Key verification items include insulation thickness, concentricity, partial-discharge performance, hot-set cross-linking degree (IEC 60811), and long-term electrical tests.<\/p>\n\n\n\n

    Process controls that must be specified and monitored:<\/p>\n\n\n\n

      \n
    • Triple-layer thickness and eccentricity (closed-loop X-ray or laser measurement).<\/li>\n\n\n\n
    • Nitrogen purity (\u226599.5 %) and stable pressure.<\/li>\n\n\n\n
    • Multi-zone tube temperature profile.<\/li>\n\n\n\n
    • Conductor preheat temperature.<\/li>\n\n\n\n
    • Compound dryness and peroxide activity.<\/li>\n\n\n\n
    • Residence time matched to insulation thickness and compound.<\/li>\n\n\n\n
    • Post-extrusion degassing time (by-products, especially methane, must be reduced before metallic screening and sheathing; several days is typical).<\/li>\n<\/ul>\n\n\n\n

      Insulation screen is normally strippable below 35 kV and bonded (non-strippable) above 35 kV. Conductor screen is always cross-linkable semi-conductive compound. XLPE compounds are peroxide-based; moisture-cure silane compounds are not used on these lines.<\/p>\n\n\n\n

      What are the principal failure modes and how are they prevented?<\/h2>\n\n\n\n
      Failure mode<\/th>Typical cause<\/th>Prevention<\/th><\/tr><\/thead>
      Insulation droop \/ eccentricity<\/td>Thick insulation on small conductor, low viscosity near conductor<\/td>Entry heat treatment, steeper catenary, higher-viscosity XLPE, active sag control<\/td><\/tr>
      Voids \/ micro-voids<\/td>Insufficient N\u2082 pressure, rapid cooling<\/td>Maintain design pressure, controlled cooling profile<\/td><\/tr>
      Interface contamination<\/td>Tandem instead of true triple extrusion<\/td>Single triple crosshead co-extrusion<\/td><\/tr>
      Incomplete cross-linking<\/td>Short residence time, low temperature, aged compound<\/td>Match speed to tube length; hot-set verification<\/td><\/tr>
      Water-tree precursors<\/td>Residual moisture (steam cure or wet compound)<\/td>Dry nitrogen cure + properly dried compounds<\/td><\/tr>
      High residual methane<\/td>Short transition zone, rapid cool-down<\/td>Optimized transition zone length and temperature profile<\/td><\/tr>
      Start-up scrap<\/td>Long transition<\/td>Automated ramp, recipe systems, inline measurement<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      \"\"<\/figure>\n\n\n\n
      \"\"<\/figure>\n\n\n\n

      Key takeaways<\/h2>\n\n\n\n
        \n
      • A Triple Layer Co-Extrusion Dry Cure CCV Line extrudes conductor screen + XLPE + insulation screen in one pass and cross-links under pressurized nitrogen in a catenary tube.<\/li>\n\n\n\n
      • It is the standard process for 6\u201335 kV and many 110 kV XLPE power cables; dry cure avoids the moisture that causes water-treeing.<\/li>\n\n\n\n
      • Typical MV lines use \u03a665\/150\/90 extruders, half-catenary heating sections of 41\u201354 m, speeds to 30 m\/min, and nitrogen at ~1.0\u20132.5 MPa.<\/li>\n\n\n\n
      • Finished cable must satisfy IEC 60502-2 or IEC 60840 plus hot-set verification of cross-link density.<\/li>\n\n\n\n
      • Critical controls are concentricity, nitrogen pressure\/purity, multi-zone temperature profile, residence time and sag management.<\/li>\n<\/ul>\n\n\n\n

        <\/p>","protected":false},"excerpt":{"rendered":"

        A Triple Layer Co-Extrusion Dry Cure CCV Line is a continuous catenary vulcanization system that simultaneously extrudes the conductor screen,<\/p>","protected":false},"author":1,"featured_media":31139,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_joinchat":[],"footnotes":""},"categories":[565],"tags":[],"class_list":["post-31134","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized-en"],"_links":{"self":[{"href":"https:\/\/doingcable.com\/fr\/wp-json\/wp\/v2\/posts\/31134","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/doingcable.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/doingcable.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/doingcable.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/doingcable.com\/fr\/wp-json\/wp\/v2\/comments?post=31134"}],"version-history":[{"count":1,"href":"https:\/\/doingcable.com\/fr\/wp-json\/wp\/v2\/posts\/31134\/revisions"}],"predecessor-version":[{"id":31140,"href":"https:\/\/doingcable.com\/fr\/wp-json\/wp\/v2\/posts\/31134\/revisions\/31140"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/doingcable.com\/fr\/wp-json\/wp\/v2\/media\/31139"}],"wp:attachment":[{"href":"https:\/\/doingcable.com\/fr\/wp-json\/wp\/v2\/media?parent=31134"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/doingcable.com\/fr\/wp-json\/wp\/v2\/categories?post=31134"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/doingcable.com\/fr\/wp-json\/wp\/v2\/tags?post=31134"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}