BS-7870-4.13-2001.pdf

BRITISH STANDARD BS 7870-4.13: 2001 Incorporating Corrigendum No. 1 LV and MV polymeric insulated cables for use by distribution and generation utilities Part 4: Specification for distribution cables with extruded insulation for rated voltages of 11 kV and 33 kV Section 4.13: Single core 33 kV copper wire/foil sheath cables ICS 29.060.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-4.13:2001 This British Standard, having been prepared under the direction of the Electrotechnical Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 September 2001 © BSI 11-2001 The following BSI references relate to the work on this British Standard: Committee reference GEL/20/2 Draft for comment 00/243878 DC ISBN 0 580 37566 8 Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee GEL/20, Electric cables, to Subcommittee GEL/20/2, Mains cables, 1 kV and above, upon which the following bodies were represented: Association of Consulting Engineers British Approvals Service for Cables British Cables Association British Plastics Federation Electricity Association ERA Technology Ltd. London Underground Ltd. UK Steel Association Amendments issued since publication Amd. No.DateComments 13519 Corrigendum 15 November 2001 In Table 1 corrections to approximate number of wires for copper wire screen (35 mm2) and to short circuit rating text. Corrections to earth fault rating text in Annex G Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-4.13:2001 © BSI 15 November 2001 i Contents Committees responsibleInside front cover Forewordii 1Scope1 2Normative references1 3Voltage designation1 4Construction and dimensions1 5Tests5 6Routine tests6 7Sample tests6 8Type tests8 Annex A (informative) Guidance on selection of single core copper foil sheath cables13 Annex B (informative) Guidance on type tests13 Annex C (normative) Water penetration test14 Annex D (normative) Peel strength of copper foil overlap16 Annex E (normative) Sidewall pressure test17 Annex F (normative) Impact test18 Annex G (normative) Earth fault spiking test19 Bibliography21 Figure C.1 Water penetration test15 Figure D.1 Peel strength of copper foil overlap16 Figure E.1 Sidewall pressure test17 Figure F.1 Impact test18 Table 1 19/33 kV single core cables having stranded copper conductors4 Table 2 Schedule of tests5 Table 3 D.C. resistance of copper wire/foil sheath6 Table 4 Cross-linked polyethylene (XLPE) and ethylene propylene rubber compound (EPR) insulation9 Table 5 Medium density polyethylene (MDPE) oversheath10 Table 6 Compatibility requirements10 Table 7 Tan ? in relation to voltage11 Table 8 Tan ? in relation to temperature11 Table A.1 Information to be specified by the user13 Table E.1 Sidewall pressure17 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-4.13:2001 ii© BSI 15 November 2001 Foreword This section of BS 7870 has been prepared by Subcommittee GEL/20/2. BS 7870 implements the nationally applicable parts of Harmonization Documents HD 603, 604, 605, 620, 622, 626 and 627 published by the European Committee for Electrotechnical Standardization (CENELEC) in accordance with the decision of the CENELEC Technical Board. BS 7870 applies to cables for fixed installations having a rated voltage of U0/U up to and including 19/33 kV, and is published as a series of separate parts and sections, as listed in the table in the foreword of BS 7870-1. BS 7870-4.13 specifies a range of 19/33 kV extruded insulation cables having radial and longitudinal water barriers. This range of cables is to be proposed, under the CENELEC TC20 maintenance procedure, as part of a future amendment No. 2 to HD 620-50 and HD 620-70. BS 7870-4.13 is to be read in conjunction with BS 7870-1 and BS 7870-2:1999. A “Guide to use” for these types of cable is under consideration. Annex A and Annex B are informative. Annex C, Annex D, Annex E, Annex F and Annex G are normative. It has been assumed in the preparation of this British Standard that the execution of its provisions will be entrusted to appropriately qualified and experienced people, for whose use it has been produced. WARNING. This British Standard calls for the use of substances and/or procedures that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at any stage. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 21 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-4.13:2001 © BSI 15 November 2001 1 1 Scope This section of BS 7870 specifies requirements for the construction, dimensions and mechanical and physical properties of 19/33(36) kV single core cables having stranded copper conductors, cross-linked polyethylene (XLPE) or ethylene propylene rubber (EPR) extruded insulation, copper wire screen, water blocking tape(s), copper foil sheath and medium density polyethylene (MDPE) oversheath. NOTE 1The copper foil sheath may consist of either plain, corrugated or laminated copper. It is applicable to cables that are intended to be suitable for laying direct in the ground, in ducts or in air, supplied either single core or in triplex formation. NOTE 2A long term test has been included to assess performance in wet conditions. It is applicable to cables intended for operation at a continuous maximum conductor temperature of 90?C and at a maximum conductor short circuit temperature of 250?C. NOTE 3Guidance on selection of cables is given in Annex A. Guidance on type tests is given in Annex B. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this section of this British Standard. For dated references, subsequent amendments to, or revisions of, any of these publication do not apply. For undated references, the latest edition of the publications referred to applies. BS 6360:1991, Specification for conductors in insulated cables and cords. BS 7870-1, LV and MV polymeric insulated cables for use by distribution and generation utilities Part 1: General. BS 7870-2:1999, LV and MV polymeric insulated cables for use by distribution and generation utilities Part 2: Methods of test. BS EN 60811-1-1:1995, Insulating and sheathing materials of electric cables. Common test methods Part 1-1: General application Measurement of thickness and overall dimensions Tests for determining the mechanical properties. BS EN 60811-1-2:1995, Insulating and sheathing materials of electric cables Common test methods Part 1-2: General application Thermal ageing methods. BS EN 60811-1-3:1995, Insulating and sheathing materials of electric cables Common test methods Part 1: General application Methods for determining the density Water absorption tests Shrinkage test. BS EN 60811-2-1:1995, Insulating and sheathing materials for electric cables Common test methods Part 2-1: Methods specific to elastomeric compounds Ozone resistance, hot set and mineral oil immersion tests. BS EN 60811-3-1:1995, Insulating and sheathing materials for electric cables Common test methods Part 3-1: Methods specific to PVC compounds Pressure test at high temperature Tests for resistance to cracking. 3 Voltage designation Cables are designated by the voltages U0, U and Um, expressed in the form U0/U (Um). The voltage designation of cables in this standard is 19/33 (36) kV. 4 Construction and dimensions 4.1 Conductors Conductors shall be stranded copper, conforming to BS 6360 (class 2) in the following sizes: 150 mm2, 185 mm2, 240 mm2, 300 mm2, 400 mm2, 500 mm2, 630 mm2 and 800 mm2. NOTEAluminium conductors, other sizes and constructions including longitudinal water blocking may be provided by agreement between the manufacturer and the purchaser. Conformity shall be checked by visual examination as specified in 7.1. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-4.13:2001 2© BSI 15 November 2001 4.2 Screens and insulation 4.2.1 Application The insulation and the semi-conducting screens shall be applied as a continuous single pass triple extrusion, free of factory repairs. NOTEPrecautions should be taken to ensure that gaseous cross-linking by-products are adequately removed from the core prior to supply. 4.2.2 Conductor screen A conductor screen consisting of an extruded layer of semi-conducting compound, which shall be cross-linked during manufacture of the cable, shall be applied over the conductor. The extruded layer shall be continuous and shall cover the surface of the conductor completely. It shall be fully bonded to the insulation and shall not separate from the insulation due to the effects of bending, load cycling and short-circuit. NOTEA semi-conducting tape may be applied prior to the extruded layer by agreement between the manufacturer and the purchaser. Conformity shall be checked by the test methods specified in 7.2. 4.2.3 Insulation The insulation shall be XLPE or EPR, conforming to the requirements specified in Table 4. The insulation shall be applied by extrusion and cross-linked to form a compact and homogeneous layer. The colour of the insulation shall be such that it is easily distinguishable from the screening materials. The thickness of the insulation shall conform to the specifications in Table 1. Conformity shall be checked by the test methods specified in 7.3. 4.2.4 Insulation screen The insulation screen shall consist of an extruded layer of cross-linked semi-conducting compound. The screen shall be fully bonded to the insulation. It shall be continuous and shall cover the surface of the insulation completely, and shall not separate from the insulation due to the effects of bending, load cycling or short-circuit. Conformity shall be checked by the test methods specified in 7.5. 4.3 Metallic screen A layer of copper wires shall be applied over the semi-conducting insulation screen in a single helical layer. The approximate number and diameter of the wires and the earth fault capability, based upon either a 35 mm2 or 50 mm2 copper wire screen with no contribution from the copper foil sheath, shall be as given in Table 1. The wires shall be spaced with an average gap not greater than 4 mm and no gap shall exceed 8 mm. NOTE 1Where a greater earth fault capability is required, this should be specified by the purchaser. NOTE 2A semi-conducting bedding tape may be applied under the metallic screen and longitudinal water blocking may be provided by agreement between the manufacturer and the purchaser. Conformity shall be checked by visual examination as specified in 7.7. 4.4 Water blocking tape Semi-conducting water blocking tape(s) shall be applied over the copper metallic screen to form a compact and circular layer. NOTEOther water blocking materials may be used by agreement between the manufacturer and the purchaser. Conformity shall be checked by the test methods specified in 7.8. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-4.13:2001 © BSI 15 November 2001 3 4.5 Copper foil sheath A copper foil sheath shall be longitudinally applied over the water blocking tape(s) with a minimum overlap of 7 mm. The copper foil overlap shall be sealed to prevent ingress of moisture and the copper foil shall not show any mechanical damage due to the effects of bending, load cycling or short-circuit. The approximate thickness of the copper foil sheath shall conform to the specifications in Table 1. NOTEOther metallic foils may be used by agreement between the manufacturer and the purchaser. Conformity shall be checked by the test methods specified in 7.9. 4.6 Oversheath The oversheath shall be an extruded layer of black medium density polyethylene (MDPE) conforming to the requirements specified in Table 5. The thickness of the oversheath shall conform to the specifications in Table 1. NOTE 1Alternative materials or colours may be provided by agreement between the manufacturer and the purchaser. NOTE 2When required by the purchaser an outer semi-conducting coating may be applied to serve as an electrode for a voltage test on the oversheath. Conformity shall be checked by the test methods specified in 7.10. 4.7 Triplex cables Cables in triplex formation shall be laid up with a right-hand direction of lay. Coloured, non-hygroscopic marker tapes shall be included within each single core cable to provide phase identification. NOTEAlternative methods of marking may be used by agreement between the manufacturer and the purchaser. 4.8 Marking 4.8.1 External marking The external surface of the cable shall be legibly marked with the following elements. The marking of elements a) to d) shall be by embossing or by indenting on the oversheath. The marking of element e) shall be by embossing, indenting or printing on the oversheath. Elements a), b) and c) shall appear on two or more primary lines along the axis of the cable, approximately equally spaced around the circumference of the cable. Elements d) and e) shall appear on at least one line. NOTE 2Elements d) and e) may be on one of the primary lines or a secondary line or lines and need not be on the same line. The letters and figures shall consist of upright block characters. The characters shall have a minimum height of 3 mm. The distance between the end of one element of marking and the beginning of the next identical element of marking shall be not greater than 550 mm for elements a), b) and c), and not greater than 1 100 mm for elements d) and e). Conformity shall be checked by visual examination and measurement as specified in 6.6. 1) Marking BS 7870-4.13:2001 on or in relation to a product represents a manufacturers declaration of conformity, i.e. a claim by or on behalf of the manufacturer that the product meets the requirements of the standard. The acc