BS-7870-2-1999.pdf

BRITISH STANDARD BS 7870-2:1999 Incorporating Amendment No. 1 LV and MV polymeric insulated cables for use by distribution and generation utilities Part 2: Methods of test (Implementation of HD 605) ICS 29.060.20 ? Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-2:1999 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 June 1999 © BSI 19 November 2004 The following BSI references relate to the work on this standard: Committee reference GEL/20/2 Draft announced in Standards Update January 1998 ISBN 0 580 28277 5 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 Cable Makers Confederation British Plastics Federation ERA Technology Ltd. Electricity Association Engineering Equipment and Materials Users Association Institution of Incorporated Executive Engineers London Underground Ltd. UK Steel Association Amendments issued since publication Amd. No. DateComments 1518519 November 2004 See national foreword Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-2:1999 © BSI 19 November 2004 i Contents Page Committees responsibleInside front cover Forewordiii Section 1. General 1.1Scope1 1.2Normative references1 1.3Classification of tests2 1.4Sampling2 1.5Test conditions2 Section 2. Non-electrical tests 2.1Dimensional measurements3 2.2Mechanical tests on non-metallic components7 2.3Mechanical tests on metallic components10 2.4Non-electrical tests on samples of complete cable10 2.5Physical and chemical tests18 Section 3. Electrical tests 3.1Electrical resistance25 3.2Voltage tests25 3.3Insulation resistance tests28 3.4Not applicable30 3.5Not applicable30 3.6Spark tests30 3.7Not applicable30 3.8Heating cycle test30 3.9Measurements of electrical resistivity of the semi-conducting screens32 3.10 Partial discharge test36 3.11 Tan ¸ measurement38 3.12 Not applicable38 3.13 Adherence of screens at short circuit temperature38 3.14 Resistivity test for water blocking tape39 Section 4. Fire performance tests 4.1Flame propagation tests41 4.2 Smoke emission tests43 4.3Corrosive gas emission tests46 Section 5. Long term tests 5.1Thermal endurance tests53 5.2Pulling lubricant immersion test59 5.3Long term water immersion test59 5.4Long term voltage test60 Bibliography65 Figure 2.1.10.5 Irregularities of semi-conducting layers and insulation6 Figure 2.2.2.2 Test piece for tear resistance test method 27 Figure 2.4.3 Sheath penetration test rig13 Figure 2.4.5 Abrasion test14 Figure 2.4.6 Cut through tool for testing cable sheaths15 Figure 2.4.9 Equipment for water penetration tests16 Figure 2.5.5 Dishes and templates20 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-2:1999 ii© BSI 19 November 2004 Page Figure 2.5.9 Apparatus for measuring swell height of water blocking tape22 Figure 2.5.14 Electrochemical test of pad material or semi-conducting tape24 Figure 3.3.1 Height of shaped conductors and cores29 Figure 3.9.3a) Test piece and arrangement of electrodes for measurement of resistivity of conductor screen of circular core34 Figure 3.9.3b) Test piece and arrangement of electrodes for measurement of resistivity of insulation screen of circular core35 Figure 3.9.3c) Arrangement of test piece, electrodes and insulating strips for measurement of resistivity of conductor and insulation screens of shaped core36 Figure 4.2.2 Arrangement for smoke test method 245 Figure 4.3.1.1 Diagrammatic arrangement of the pyrolysis line gas collection and recording of acid gas emissions for test method 148 Figure 4.3.1.2 Test behaviour for method 149 Figure 5.1.1 Accelerated ageing of a cable with a 40 year service life at a mean operating temperature of 40 °C54 Figure 5.1.2 Accelerated ageing of a cable with a 40 year service life at a mean operating temperature of 55 °C55 Figure 5.1.3 Accelerated ageing of a cable with a 40 year service life at a mean operating temperature of 60 °C56 Figure 5.1.4 Accelerated ageing of a cable with a 40 year service life at a mean operating temperature of 75 °C57 Table 2.4.5 Vertical force on cable during abrasion test12 Table 3.1.2 Temperature correction multiplication factors26 Table 5.1.1 Variation of accelerated ageing time with activation energy58 Table 5.3.1.1 Minimum insulation resistance59 Table 5.3.1.2 Test voltage60 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-2:1999 © BSI 19 November 2004 iii Foreword BS 7870 was prepared by Technical Committee GEL/20. It 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. Amendment No. 1 introduces the method for the harmonized long duration test that was published by CENELEC in 2002 as HD 605 A3. It also draws attention to the risks of water contamination by Legionella pneumophila bacteria during conditioning and ageing procedures. The start and finish of text introduced or altered by amendment is indicated in the text by tags !“. Tags indicating changes to text carry the number of the amendment. For example, text altered by Amendment No. 1 is indicated by !“. BS 7870 applies to cables for fixed installations having a rated voltage 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 Part 1. BS 7870-2 implements the relevant parts of HD 605 and is to be read in conjunction with BS 7870-1:1996 This new edition of BS 7870-2 implements the parts of amendment no. 1 to CENELEC HD 605 that are applicable to the United Kingdom. It supersedes BS 7870-2:1996, which is withdrawn. The numbering system used in this part aligns with the numbering system used in HD 605 to facilitate cross-reference except for Section 1. As other Harmonization Documents are implemented, this part will be revised so that all the relevant additional methods of test are included. 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. 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 to iv, pages 1 to 65 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 12:10:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-2:1999 © BSI 19 November 2004 1 Section 1. General 1.1 Scope BS 7870-2 collates and specifies the additional test methods to be used for testing polymeric insulated and sheathed electric cables, of rated voltage up to and including 19/33 kV, intended for use by distribution and generation utilities. Test methods in this part of BS 7870 are additional to those already harmonized, e.g. those given in BS 4066 and BS EN 60811, and are used for testing cable types specified in Parts 3 to 8. Full test conditions (e.g. temperatures, durations) and/or test requirements are not specified in this part. Such data needed to carry out the tests are given in the particular sections. Tests applicable to each type of cable are given in the particular sections, which state also the sequence, the frequency of test, and the possibility of repeating tests. NOTEThe words “particular section” refer throughout to the section of BS 7870 in which a particular cable type is specified. 1.2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of this British Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undated references, the latest edition of the publication referred to applies. BS 358, Method for the measurement of voltage with sphere-gaps (one sphere earthed). BS 903-A26:1995, Physical testing of rubber Part A26: Method for determination of hardness. BS 903-A59:1990, Physical testing of rubber Part A59: Methods using plastimers. BS 923-1, Guide on high-voltage testing techniques Part 1: General. BS 4066-3, Tests on electric cables under fire conditions Part 3: Tests on bunched wires and cables. BS 4828:1985, Guide for partial discharge measurements. BS 5099:1992, Specification for spark testing of electric cables. BS 6360:1991, Specification for conductors in insulated cables and cords. BS 6469-99.2:1992, Insulating and sheathing materials of electric cables Part 99: Test methods used in the United Kingdom but not specified in Parts 1 to 5 Section 2: Electrical tests. BS 7622-1, Measurement of smoke density of electric cables burning under defined conditions Part 1: Test apparatus. BS 7622-2, Measurement of smoke density of electric cables burning under defined conditions Part 2: Test procedure and requirements. BS EN 10002-1, Tensile testing of metallic materials Part 1: Method of test at ambient temperature. BS EN 60060-2, High-voltage test techniques Part 2: Measuring systems. BS EN 60811-1-1:1995, Insulating and sheathing materials of electric and optical 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, Common test methods for insulating and sheathing materials of electric and optical cables Part 1-2: General application Thermal ageing methods. BS EN 60811-2-1:1998, Insulating and sheathing materials of electric and optical cables Common test methods Part 2-1: Methods specific to elastomeric compounds Ozone resistance, hot set and mineral oil immersion tests. IEC 60502, Power cables with extruded insulation and their accessories for rated voltages from 1 kV (Um = 1.2 kV) up to 30 kV (Um = 36 kV). IEC 60502-2, Cables for rated voltages from 6 kV (Um = 7.2 kV) up to 30 kV (Um = 36 kV). Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-2:1999 2 © BSI 19 November 2004 Section 1 1.3 Classification of tests The classification of tests is given in BS 7870-1. 1.4 Sampling If a marking is indented in the insulation or sheath surface, the samples used for the tests shall be taken so as to include such markings. For multicore cables, except for the test specified in 2.1.1, not more than three cores (of different colours, if available) shall be tested unless otherwise specified. NOTEThe size and number of samples are given either in this part of BS 7870 or in the particular cable specifications. 1.5 Test conditions 1.5.1 Ambient temperature Tests shall be made at an ambient temperature within the range 5 °C to 35 °C unless otherwise specified in the details for the particular test. 1.5.2 Tolerance on temperature values Unless otherwise specified in the particular specification, the tolerance on temperature values quoted in the test methods shall be as follows: 1.5.3 Frequency and waveform of power-frequency test voltages Unless otherwise specified, alternating test voltages shall have a frequency between 49 Hz and 61 Hz. The waveform shall be substantially sinusoidal. 1.5.4 Pre-conditioning Where preconditioning is specified, the tests shall be carried out not less than 16 h after the extrusion or cross-linking, if any, of the insulating or sheathing compounds. Specified temperature, t °C Tolerance °C p40 k t k 0±2 0 150±3 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:10:58 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870-2:1999 © BSI 19 November 2004 3 Section 2. Non-electrical tests 2.1 Dimensional measurements 2.1.1 Measurement of insulation thickness 2.1.1.1 Procedure The thickness of insulation shall be measured in accordance with BS EN 60811-1-1:1995, 8.1. Conformity shall be checked on each core of cables having up to five cores, and on the number of cores stated in the individual specification for cables with more than five cores. 2.1.1.2 Evaluation of results The average of the values (expressed in millimetres), obtained as specified in the individual specification for the insulation from each core, shall be calculated to two decimal places and rounded off as given below. This shall be taken as the average value of the thickness of insulation. If in the calculation the second decimal figure is five or more, the first decimal figure shall be raised to the next number thus, for example, 1.74 shall be rounded off to 1.7 and 1.75 to 1.8. The lowest of all values obtained shall be taken as the minimum thickness of insulation at any place. 2.1.2 Measurement of non-metallic sheath thickness 2.1.2.1 Procedure The thickness of sheath shall be measured in accordance with BS EN 60811-1-1:1995, 8.2 2.1.2.2 Evaluation of results The average of the values (expressed in millimetres), obtained as specified in the individual specification for the sheath, shall be calculated to two decimal places and rounded off as given below. This shall be taken as the average value of the thickness of the sheath. If in the calculation the second decimal figure is five or more, the first decimal figure shall be raised to the next number, thus, for example, 1.74 shall be rounded off to 1.7 and 1.75 to 1.8. The lowest of all values obtained shall be taken as the minimum thickness of sheath at any place. 2.1.3 Measurement of ca