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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 7870 : Part 2 : 1996 I
2、CS 29.060.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW LV and MV polymeric insulation cables for use by distribution and generation utilities Part 2. Methods of test (Implementation of HD 605) Licensed Copy: London South Bank University, London South Bank University, Fri
3、 Dec 08 11:57:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI This British Standard, having been prepared under the direction of the Electrotechnical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 October 1996 BSI 1996 The following BSI references re
4、late to the work on this standard: Committee reference GEL/20/2 Draft for comment 95/212753 Update ISBN 0 580 26254 5 BS 7870 : Part 2 : 1996 Amendments issued since publication Amd. No.DateText affected Committees responsible for this British Standard The preparation of this British Standard was en
5、trusted by Technical Committee GEL/20, Electric cables, to Subcommittee GEL/20/2, Mains cables 1kVand above, upon which the following bodies were represented: Association of Consulting Engineers British Approvals Service for Cables British Cable Makers Confederation British Iron and Steel Producers
6、Association British Plastics Federation British Railways Board ERATechnology Ltd. Electricity Association Engineering Equipment and Materials Users Association Institution of Incorporated Executive Engineers London Underground Ltd. Licensed Copy: London South Bank University, London South Bank Unive
7、rsity, Fri Dec 08 11:57:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870 : Part 2 : 1996 BSI 1996i Contents Page Committees responsibleInside front cover Forewordii Methods of test Section 1. General 1.1Scope1 1.2References1 1.3Classification of tests1 1.4Sampling1 1.5Test conditions1 Section 2
8、. Non-electrical tests 2.1Dimensional measurements2 2.2Mechanical tests on non-metallic components3 2.4Non-electrical tests on samples of complete cable4 2.5Physical and chemical tests5 Section 3. Electrical tests 3.1Electrical resistance6 3.2Voltage tests6 3.6Spark tests6 Figure 1Apparatus for wate
9、r penetration tests5 List of referencesInside back cover Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:57:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii BSI 1996 BS 7870 : Part 2 : 1996 Foreword BS 7870 was prepared by Technical Subcommittee GEL/20/2. It
10、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 insta
11、llations 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. Part 2 of BS 7870 implements the relevant tests of HD 605 and is to be read in conjunction with BS 7870 : Part 1 : 1996. T
12、he 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
13、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. The methods of test described in this British Standard do not detail all precautions necessary to meet th
14、e requirements of the Health and Safety at Work, etc, Act 1974. Attention should be paid to any appropriate safety precautions and the tests should only be carried by authorized personnel. Compliance with a British Standard does not of itself confer immunity from legal obligations. Licensed Copy: Lo
15、ndon South Bank University, London South Bank University, Fri Dec 08 11:57:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7870 : Part 2 : 1996 BSI 19961 Section 1. General 1.1 Scope Part 2 of BS 7870 collates and specifies the additional test methods to be used for testing polymeric insulated and
16、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 speci
17、fied in Parts 3 to 8. NOTE. Further additional test methods for cable types in Part 4 to Part 8 are in preparation. 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 Section
18、s. Tests applicable to each type of cable are given in the particular Section, which state also the sequence, the frequency of test, and the possibility of repeating tests. NOTE. The words particular Section refer throughout to the Section of BS 7870 in which a particular cable type is specified. 1.
19、2 References 1.2.1 Normative references This Part of BS 7870 incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate place in the text and the cited publications are listed on the inside back cover. For dated references,
20、 only the edition cited applies; any subsequent amendments to or revisions of the cited publication apply to this British Standard only when incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendmen
21、ts. 1.2.2 Informative references This Part of BS 7870 refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 1.3 Classifi
22、cation of tests The classification of tests is given in Part 1 of BS 7870. 1.4 Sampling The size and number of samples are given either in this Section or in the particular Sections. If a marking is indented in the insulation or sheath surface, the samples used for the tests shall be taken so as to
23、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. 1.5 Test conditions 1.5.1 Ambient temperature Tests shall be made at an ambient temperature within the range
24、 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 are as follows. Specified temperature, tTolerance CC 2 40 #
25、 t #0 2 0 150 3 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 specified the tests shall be carried out no
26、t less than 16 h after the extrusion or cross-linking, if any, of the insulating or sheathing compounds. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:57:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 BSI 1996 BS 7870 : Part 2 : 1996 Section 2. Non-electri
27、cal 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 8.1 of BS EN 60811-1-1 : 1995. Conformity shall be checked on each core of cables having up to five cores, and on the number of cores st
28、ated 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 rounde
29、d 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
30、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 8.2 of BS EN 60811-1-1 : 1995. 2.1.2.2 Evaluation of results The average of the
31、 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
32、 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 Not applicable 2.1.4 Measurement of wires, strip
33、s and tapes 2.1.4.1 Not applicable 2.1.4.2 Not applicable 2.1.4.3 Wires, strips and tapes for armour a) Not applicable b) Not applicable c) Metallic tapes thickness Take and straighten a sample of each armour tape, remove the non-metallic coating if any, and determine the tape thickness at six diffe
34、rent places by using a micrometer or vernier calliper with flat noses. Take the smallest value to be compared with the specified thickness with a tolerance given in the particular specification. 2.1.5 Measurement of thickness of metallic sheath a) Strip method. The measurement shall be made on a tes
35、t piece of sheath about 50 mm in length removed from the finished cable length. The test piece shall be taken a sufficient distance from the cable end to allow a proper measurement to be made. The piece shall be slit longitudinally and carefully flattened. After cleaning the test piece, a sufficient
36、 number of measurements shall be taken along the circumference of the sheath and not less than 10 mm away from the edge of the flattened piece to ensure that the minimum thickness is measured. The measurements shall be made with a micrometer with plane faces of 4 mm to 8 mm diameter and an accuracy
37、of0.01 mm. 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 calculat
38、ion 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. b) Not applicable 2.1.6 N
39、ot applicable 2.1.7 Not applicable 2.1.8 Not applicable 2.1.9 Measurement of rubber layer thickness 2.1.9.1 Single rubber layer The diameters over the copper concentric neutral/earth conductor and the laid-up cores shall be determined by a diameter tape at the same position. The nominal thickness of
40、 the rubber layer is to be taken as half the difference between these two diameters, less the diameter of one copper wire comprising the neutral/earth layer. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:57:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Sect
41、ion 2BS 7870 : Part 2 : 1996 BSI 19963 2.1.9.2 Double rubber layer The diameters over the anti-corrosion layer and over the core of single-phase cables, or over the laid-up cores of three-phase cables shall be determined by diameter tape at the same position. The average thickness of the anti-corros
42、ion layer is to be taken as half the difference between these two diameters. For three-phase cables with circular conductors and without fillers the value indicated by the diameter tape measurement over the cores shall be increased by 10 per cent to give the true diameter over the laid-up cores. 2.2
43、 Mechanical tests on non-metallic components 2.2.1 Not applicable 2.2.2 Not applicable 2.2.3 Not applicable 2.2.4 Not applicable 2.2.5 Determination of hardness for elastomeric insulation and sheath The hardness of elastomeric insulation and sheath shall be determined in accordance with BS 903 : Par
44、t A26. 2.2.6 Not applicable 2.2.7 Plasticity and elongation at break of single (S) and double (D) rubber layers for concentric neutral cables 2.2.7.1 Preparation of rubber from cable A piece of the completed cable taken from any size of 3 3 185 mm2or larger, not less than 600 mm long, shall have the
45、 sheath removed by making two longitudinal cuts through the sheath to either the copper wire neutral or the outer rubber layer. The sheath shall be removed in two halves. The operation shall leave the outer rubber layer (D) virtually untouched. With the unsheathed (D) cable held securely two circumf
46、erential marks shall be made around the cable at measured distances at one end with the aid of a non-metallic blade. The distance between the marks shall be such that on removal over this length a total weight of rubber from the two layers shall be at least 200 g. The outer rubber layer shall be rem
47、oved between the two circumferential marks by paring it off the neutral wires with the aid of a non-metallic blade. The rubber so removed shall be retained. The neutral wires shall be removed from the cable by pulling them individually outwards from one end of the cable sample. For type (S) the wire
48、s shall be removed over a longer distance so as to guarantee 200 g from the inner layer alone. The inner layer shall be removed over the required distance by paring or by making appropriately spaced longitudinal cuts down to the laid up cores and removing the rubber strips. Any fragments of the bind
49、er tape over the laid up cores shall be removed. Care shall be taken to avoid contamination with aluminium or copper dust or slivers. An homogenized sample shall be prepared by adding the samples from the inner and outer layers for type (D) or the single layer in type (S) and passing through a cool mill 10 times. The rolls shall be maintained at a temperature of (235) C and the friction ratio set at between 1.15:1 and 1.25:1. The rubber shall be rolled up after passing through the nip and the rolled up sample presented end-wise to the nip for the next pass. The mill nip
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