BS-4579-3-1976.pdf

BRITISH STANDARD CONFIRMED AUGUST 1988 BS 4579-3: 1976 Incorporating Amendment No. 1 Specification for Performance of mechanical and compression joints in electric cable and wire connectors Part 3: Mechanical and compression joints in aluminium conductors UDC 621.315.687:621.315.55:669.71 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 01:48:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4579-3:1976 This British Standard, having been prepared under the direction of the Electrical Industry Standards Committee, was published under the authority of the Executive Board on 31 August 1976 © BSI 03-1999 The following BSI references relate to the work on this standard: Committee reference ELE/95/2 Draft for comment 73/28886DC ISBN 0 580 09455 3 Cooperating organizations The Electrical Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Associated Offices Technical Committee Association of Consulting Engineers Association of Manufacturers of Domestic Electrical Appliances Association of Mining Electrical and Mechanical Engineers Association of Supervisory and Executive Engineers British Electrical and Allied Manufacturers Association British Electrotechnical Approvals Board for Household Equipment British Non-Ferrous Metals Federation British Radio Equipment Manufacturers Association British Railways Board Crown Agents for Oversea Governments and Administrations Department of Energy* Department of Prices and Consumer Protection Department of the Environment Electric Cable Makers Confederation* Electrical Contractors Association* Electrical Contractors Association of Scotland Electrical Research Association Electricity Supply Industry in England and Wales* Electronic Engineering Association Engineering Equipment Users Association Health and Safety Executive (HM Factory Inspectorate) Institution of Electrical and Electronics Technician Engineers Institution of Electrical Engineers Lighting Industry Federation Limited Ministry of Defence* National Inspection Council for Electrical Installation Contracting Oil Companies Materials Association* Post Office* South of Scotland Electricity Board The Government departments and scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: Association of Manufacturers Allied to the Electrical and Electronics Industries Copper Development Association Electrical Installation Equipment Manufacturers Association London Transport Executive National Coal Board Amendments issued since publication Amd. No.Date of issueComments 3607August 1981Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 01:48:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4579-3:1976 © BSI 03-1999i Contents Page Cooperating organizationsInside front cover Forewordii 1Scope1 2References1 3Definitions1 4Classification1 5Requirements1 6Test specimens2 7Sequence of tests3 8Resistance measurement3 9Short circuit test3 10Electrical load cycling test4 11Tensile strength test5 12Test reports5 Appendix A Electrical load cycling test rigs6 Appendix B Graphical representation of electrical load cycling test results9 Appendix C Mathematical acceptance criterion11 Appendix D Tensile tests17 Appendix E Determination of equivalent r.m.s. short circuit current20 Appendix F Schedule of technical information21 Figure 1 Potential points for resistance measurement2 Figure 2 Through connectors6 Figure 3 Terminations6 Figure 4 Branch and service connectors (current injection method)7 Figure 5 Branch and service connectors (reactance control method)7 Figure 6 Mathematical acceptance criterion for specimen A15 Figure 7 Mathematical acceptance criterion for specimen B16 Figure 8 Moulds for cast resin blocks machined from aluminium block17 Figure 9 Tensile testing jig for “right angle” connectors18 Figure 10 Jig in position in tensile testing machine19 Figure 11 Tensile testing jig with interchangeable plates for “parallel” type connectors19 Figure 12 Jig in position in tensile testing machine20 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 01:48:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4579-3:1976 ii © BSI 03-1999 Foreword This British Standard has been prepared under the authority of the Electrical Industry Standards Committee and is based on a proposal submitted by the Electricity Council. When a connector or termination, forming a joint, meets the requirements of this standard, it is expected that in service: a) the resistance of the joint will remain stable; b) the temperature of the joint will be of the same order as that of the conductor; c) if the intended use demands, application of short circuit currents will not cause undue deterioration; d) the mechanical strength will be adequate. The standard is generally representative of service conditions but does not, for example, take into account the tensile and compressive stresses to which the conductor is subjected as a result of variations in load currents. The stresses depend considerably on the overall design of the installation in which the conductor is used. It will be understood that these tests in air cannot simulate operations in all possible environments. NOTEThe performance of compression joints on conductors other than aluminium is the subject of BS 4579-1 and BS 4579-2. 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 22, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 01:48:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4579-3:1976 © BSI 03-19991 1 Scope This Part of BS 4579 specifies requirements for the performance of mechanical joints and compression joints in electric cable and wire connectors, for use on aluminium conductors of cross-sectional area 16 mm2 and above. These conductors may be solid circular, solid sector shaped, solid sectoral circular, stranded circular, shaped stranded and compacted circular. The type of cable concerned may be either paper-insulated in accordance with BS 6480 or polymeric insulated in accordance with BS 6346, having solid or stranded aluminium conductors in accordance with BS 6360. 2 References The titles of the publications referred to in this standard are listed on the inside back cover. 3 Definitions For the purposes of this Part of BS 4579 the following definitions apply. 3.1 connector a device for connecting two or more conductors 3.2 termination a device for connecting a conductor to other equipment 3.3 through connector a connector for connecting two consecutive lengths of conductor 3.4 branch connector a connector for connecting a branch conductor to a main conductor 3.5 service connector a connector for connecting a service conductor to a main conductor 3.6 joint the body of the connector or termination and that part of the conductor that has been brought into intimate contact with it by compression or other mechanical means 3.7 control conductor a length of unjointed conductor the central part of which is used during load cycling to provide the reference for temperature and resistance measurement 4 Classification For the purposes of this standard, connectors and terminations are classified as follows: Type 1 connectors shall satisfy all the requirements of this standard. Type 2 connectors shall satisfy all the requirements of this standard except that they are not required to be subjected to the short circuit test (see clause 9). 5 Requirements 5.1 Joint resistance 5.1.1 Initial value. The initial resistance, A to B (see Figure 1), of each specimen, when measured as described in clause 8, shall not differ by more than 50 % or 5 47, whichever is the greater, from the mean of the overall resistance of the six specimens prepared as described in 6.1. 5.1.2 Values measured in the course of the short circuit test. The resistance, A to B (see Figure 1), of each specimen, measured after each of the three applications of short circuit current as described in clause 9, shall not exceed the initial value by more than 50 % or 5 47, whichever is the greater. 5.1.3 Values measured during electrical load cycling tests 5.1.3.1 The average resistance, A to B (see Figure 1), of the test specimen taken over the last 1 000 cycles shall not exceed the average equivalent conductor resistance (see A.3), taken over the same period, by more than 50 % or 5 47, whichever is the greater. 5.1.3.2 The average resistance, A to B (see Figure 1), of the test specimen taken over the last 1 000 cycles shall not exceed the resistance of the test specimen as measured immediately before the start of the electrical load cycling test by more than 50 % or 5 47, whichever is the greater. type 1connectors and terminations used on circuits of comparatively high fault level and designed accordingly type 2connectors and terminations used on circuits protected by high breaking capacity fuses and not required to possess any special short circuit characteristics Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 01:48:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4579-3:1976 2 © BSI 03-1999 5.1.3.3 The graph of resistance, A to B (see Figure 1), against number of cycles shall demonstrate with a reasonable probability that the change (rise or fall) of resistance over the last 1 000 cycles is not more than 20 % of the average resistance over the same period. If the graph of resistance is unacceptable to either the purchaser or the supplier, the method given in Appendix C shall be used to determine the acceptability of a connector or termination. 5.1.3.4 In the event of the results of the statistical test in 5.1.3.3 being considered inconclusive by either the purchaser or the supplier, then the test shall be extended by periods of 1 000 load cycles, and the results shall be assessed as described in 5.1.3.3. 5.2 Temperature. The temperature of the connector or termination as measured during electrical load cycling in accordance with clause 10 shall not exceed the temperature of the control conductor by more than 5 °C. 5.3 Tensile strength. Connectors and terminations, when tested in accordance with the provisions of clause 11, shall satisfy the following requirements. a) A through connector, branch connector or termination shall have a breaking load not less than 60 % of that of the unjointed main or branch conductor, as appropriate. b) A service connector shall have a breaking load not less than 25 % of that of the unjointed service conductor. 6 Test specimens 6.1 Preparation. Test specimens shall be made upon insulated conductors taken from any of four types of cable namely: a) mass-impregnated, non-draining, paper-insulated cable in accordance with BS 6480; b) mass-impregnated, paper-insulated cable in accordance with BS 6480; c) pre-impregnated, paper-insulated cable in accordance with BS 6480; d) polymer-insulated cable in accordance with BS 6346. A test made with conductors from mass-impregnated, non-draining cable will be considered satisfactory evidence for all types a) to d). However, tests may be carried out using any of the types b) to d), in which case the connector or termination will be accepted as suitable only for that particular type of cable. Connectors and terminations shall be so prepared as to satisfy the requirements of 10.1 and shall be assembled and installed strictly in accordance with the manufacturers instructions without further preparation. No subsequent tightening of the connectors or terminations shall be made. Figure 1 Potential points for resistance measurement Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 01:48:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 4579-3:1976 © BSI 03-19993 In the case of through connectors, care shall be taken to ensure that the ends of the conductors are not in direct contact unless the design of the connector specifically provides for butting of the conductors. The insulation shall be retained on the conductor except as necessary to enable the connector to be assembled and the potential measuring points to be provided (see A.2) and to enable temperature-measuring devices to be placed in contact with the control conductors. 6.2 Number. The number of specimens tested shall be as specified in 6.2.1 to 6.2.4. 6.2.1 If one size of connector or termination is offered for more than one size of conductor, tests shall be made on six specimens incorporating the largest size of conductor and on six specimens incorporating the smallest conductor. In the case of branch or service connectors, tests shall be made on six specimens incorporating the largest sizes of conductor and on six specimens incorporating the smallest sizes of conductor. 6.2.2 If a connector or termination is offered for more than one shape of solid conductor, six specimens shall be tested for each shape of conductor. 6.2.3 Where a design is common over a range of connectors or terminations that includes three or more different sizes, the specimens tested shall comprise six of the largest, six of the smallest and six of one of the intermediate sizes of connector or termination. 6.2.4 Where terminations for a given shape and size of conductor are available with different palm sizes but are otherwise identical, tests shall be carried out on six terminations with the smallest palm size only. 7 Sequence of tests Before the tests are made, the testing organization shall satisfy itself that the test specimens and arrangements comply with the requirements of clause 6. Tests on each specimen shall be made in the following sequence. a) Before the specimens have been assembled into the load cycling rig: 1) initial resistance measurement by the procedure described in clause 8; 2) short circuit tests on type 1 connectors by the procedure described in clause 9. b) After the specimens have been assembled into the load cycling rig: 1) electrical load cycling by the procedure described in clause 10; 2) resistance measurement by the procedure described in clause 8. c) After completion of the load cycling test: tensile strength test by the procedure described in clause 11. 8 Resistance measurement 8.1 Procedure. The devices and instruments used for resistance measurements shall be capable of measuri