1、BRITISH STANDARD BS 7288:1990 Incorporating Amendment No. 1 Specification for Socket-outlets incorporating residual current devices (s.r.c.ds)BS 7288:1990 This British Standard, having been prepared under the direction of the Power Electrical Engineering Standards Policy Committee, was published und
2、er the authority of the Board of BSI and comes into effect on 31 August 1990 BSI 04-1999 The following BSI references relate to the work on this standard: Committee reference PEL/11 Draft for comment 89/33694 DC ISBN 0 580 18314 9 Committees responsible for this British Standard The preparation of t
3、his British Standard was entrusted by the Power Electrical Engineering Standards Policy Committee (PEL/-) to Technical Committee PEL/11, upon which the following bodies were represented: ASTA Certification Services Association of Control Manufacturers, TACMA (BEAMA Ltd.) British Lawn Mower Manufactu
4、rers Federation Consumer Policy Committee of BSI Department of Trade and Industry, Consumer Safety Unit, CA Division Electrical Installation Equipment Manufacturers Association (BEAMA Ltd.) Electricity Supply Industry in England and Wales Electronic Components Industry Federation Health and Safety E
5、xecutive Institution of Electrical Engineers National Inspection Council for Electrical Installation Contracting Portable Electric Tool Manufacturers Association Amendments issued since publication Amd. No. Date Comments 7469 January 1993 Indicated by a sideline in the marginBS7288:1990 BSI 04-1999
6、i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions and symbols 1 3 Classification 3 4 Rated values 3 5 Marking and labelling 3 6 Service conditions 4 7 Design and construction 5 8 Type tests 8 9 Routine tests 20 Appendix A Requirements relating to other sta
7、ndards in connection with s.r.c.ds 22 Appendix B Function of the test circuit 22 Appendix C Measurement of creepage distances and clearances 22 Appendix D Transformer balance test 25 Figure 1 Test circuit for earth fault breaking current test 12 Figure 2 Pendulum impact test apparatus 14 Figure 3 Te
8、st circuit for endurance test 16 Figure 4 Test circuit for circuit fault current test 17 Figure 5 Ball pressure test apparatus 19 Figure 6 Typical circuit diagram for an s.r.c.d. 22 Table 1 Type testing schedule 9 Table 2 Loading of socket-outlets for temperature rise test 11 Table 3 Endurance test
9、sequence 13 Table 4 Torque values for screws and nuts 17 Table 5 Application of glow-wire test 19 Publications referred to Inside back coverBS 7288:1990 ii BSI 04-1999 Foreword This standard has been prepared under the direction of the Power Electrical Engineering Standards Policy Committee. This st
10、andard specifies requirements for socket-outlets incorporating residual current devices (s.r.c.ds). This edition covers the use of the following types of s.r.c.d.: a) single pole with switched neutral; b) double pole; c) single pole with solid neutral. It should be noted that it is intended to withd
11、raw the requirements for single pole devices with solid neutral at some future date. 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 its
12、elf confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1to26, 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 indic
13、ated in the amendment table on theinside front cover.BS7288:1990 BSI 04-1999 1 1 Scope This British Standard specifies the requirements for socket-outlets incorporating residual current devices (s.r.c.ds) (including devices utilizing integral auxilary sources and devices with electronic circuitry) f
14、or use in fixed installations. This standard deals with protected socket-outlets having a rated voltage not exceeding 250V a.c. single phase, a rated current not exceeding 16A, a rated frequency not exceeding 400Hz and a rated residual operating current not exceeding 100mA. This standard covers sock
15、et-outlets incorporating single pole devices with switched neutral, double pole devices and single pole devices with solid neutral. Socket-outlets incorporating residual current devices (s.r.c.ds) with intentional time delays are not covered by this standard. NOTEThe titles of the publications refer
16、red to in this standard are listed on the inside back cover. 2 Definitions and symbols For the purposes of this British Standard the following definitions apply. 2.1 residual current (I % ) the root mean square (r.m.s.) value of the vector resultant of the instantaneous values of the currents flowin
17、g in the main circuit of the residual current device 2.2 socket-outlet incorporating residual current devices (s.r.c.d.) a socket-outlet for fixed installations which incorporates an integral sensing circuit that will automatically cause the switching contacts in the main circuit to open at a predet
18、ermined value of residual current 2.3 interlocked s.r.c.d. an s.r.c.d. incorporating an interlock (either mechanical or electrical) which prevents contacts of the automatic tripping function from being closed on-load 2.4 tripping current (I o% ) the minimum value of residual current that causes the
19、device to open 2.5 rated tripping current (I o%N ) (rated residual operating current) the value of residual current, assigned by the manufacturer, at which the device opens automatically under specific conditions 2.6 rated non-tripping current (I %N ) the value of residual current, assigned by the m
20、anufacturer, at which the device does not open under specified conditions 2.7 rated current of a device (I N ) the r.m.s. value of current, assigned by the manufacturer, which the main circuit of the device is capable of carrying continuously under specified conditions of use and behaviour 2.8 prosp
21、ective current the current (r.m.s. value of the a.c. component) that would flow in a circuit due to the applied voltage if each main current path of the device were replaced by a link of negligible impedance but without any other circuit change NOTEFor the purpose of this definition the term device
22、includes the short length of cable or cord used to connect the device to the test circuit. 2.9 rated voltage (U N ) the r.m.s. value of voltage, assigned by the manufacturer, to which the performance of the device is referred 2.10 rated earth fault breaking capacity the value of earth fault current
23、which the s.r.c.d., without the aid of any back-up protection, can satisfactorily break at rated voltage 2.11 rated frequency the frequency of the supply for which an s.r.c.d. is designed 2.12 pole the portion of a switching device associated exclusively with one electrically separated conducting pa
24、th of its main circuit and excluding those portions which provide a means for mounting and operating all main contacts together NOTEAll the conducting parts of a switching device included in the circuit which it is designed to close or open are considered to be the main circuit.BS 7288:1990 2 BSI 04
25、-1999 2.13 switched pole a pole containing contacts for opening and closing the current path 2.14 switched neutral a switched pole, in the neutral current path, with contacts not intended to make or break current but arranged to open after and to close before the contacts in the other switched pole
26、of the main current path 2.15 main contacts the fixed and moving contacts in the main current carrying paths 2.16 test circuit an integral circuit to enable the protective function of the device to be checked 2.17 integral auxiliary source an auxiliary source of power intended to supply the auxiliar
27、y circuit(s) which is derived from the same mains supply within the device as the load being protected 2.18 socket-outlet a device having a set of socket contacts designed to engage with the pins of corresponding plug and having terminals for the connection of appropriate conductors 2.19 accessible
28、external surfaces of s.r.c.d. all surfaces which can be touched by test finger I of BS3042:1971 when the s.r.c.d. is in normal use 2.20 s.r.c.d. with integral overcurrent protection an s.r.c.d. designed to perform the additional function of overload and/or short circuit protection NOTEFor the purpos
29、e of this standard, the s.r.c.d. is considered to have integral overcurrent protection if it can supply a local load only through a fused plug. 2.21 flush mounted s.r.c.d. an s.r.c.d. intended to be mounted in a box which is recessed into a wall or other flat surface 2.22 surface mounted s.r.c.d. an
30、 s.r.c.d. intended to be mounted on a wall or other flat surface within an associated enclosure but without the need for recessing 2.23 panel mounted s.r.c.d. an s.r.c.d. intended for incorporation into equipment panels or electrical cable trunking and which is dependent upon such incorporation for
31、its enclosure 2.24 switched s.r.c.d. an s.r.c.d. which is provided with a manual switch (which may or may not be associated with the mechanism which is sensitive to residual current) to connect or disconnect the supply to the line socket contact or to both line and neutral socket contacts and which
32、may be independent of the automatic tripping function 2.25 twin s.r.c.d. a combination of two socket-outlets incorporating residual current protection 2.26 shutter a moveable part arranged to shield the current carrying socket outlet contacts automatically when a corresponding plug is removed 2.27 a
33、ctuating member that part which is moved, pulled, pushed or turned to operate the mechanism 2.28 indicator lamp (pilot lamp) a lamp which illuminates to indicate that the socket outlet contacts are energized 2.29 terminal a means by which the installer can make an electrical connection between the a
34、ppropriate conductor and the conducting parts of the device without the use of special tools NOTE2.30, 2.31 and2.32 are examples of screw type terminals. 2.30 pillar terminal a terminal in which the conductor is inserted into a hole or cavity where it is clamped with the end of a screw or screws. Th
35、e clamping pressure may be applied directly to the end of the screw or screws or through an intermediate clamping member to which pressure is applied by the end of the screw or screwsBS7288:1990 BSI 04-1999 3 2.31 screw terminal a terminal in which the conductor is clamped under the head of the scre
36、w. The clamping pressure may be applied directly by the head of the screw or through an intermediate metallic part in direct contact with the screw, such as washer, clamping plate or anti-spread device 2.32 stud terminal a terminal in which the conductor is clamped under a nut. The clamping pressure
37、 may be applied directly by a suitably shaped nut or through an intermediate part, such as a washer, clamping plate or anti-spread device 2.33 base that part of the device retaining current carrying parts and, in general, the mechanism in position 2.34 intentional time delay the additional value of
38、non-actuating time in excess of the specified operating time given in8.9.3, for a corresponding value of residual current 2.35 type test a test of one or more devices made to a certain design to show that the design meets certain requirements 2.36 routine test a test to which each individual s.r.c.d
39、. is subjected during and/or after manufacture to ascertain whether it complies with certain criteria 2.37 earth fault current a current which flows to earth resulting from an insulation failure or the bridging of insulation 2.38 earth leakage current a current which flows to earth, in a circuit whi
40、ch is electrically sound NOTEThis current may have a capacitive component resulting from the deliberate use of capacitors. 2.39 symbols in the text of this British Standard the following symbols are used: qualified by the following subscripts: 2.40 functional earth circuit for the purposes of this B
41、ritish Standard a functional earth circuit is one connected to earth for protection against supply faults, suppression and similar functions 3 Classification Devices specified in this standard are classified as follows. a) Type of s.r.c.d.: 1) single s.r.c.d.: 2) twin s.r.c.d.: 3) unswitched s.r.c.d
42、. 4) switched s.r.c.d. (see 2.24); 5) s.r.c.d. with integral overload protection; 6) s.r.c.d. without integral overload protection. b) The number of poles as follows: 1) single pole with switched neutral; 2) double pole; 3) single pole with solid neutral (see foreword). c) The type of switching as f
43、ollows: 1) capable of being switched on-load; 2) not capable of being switched on-load (interlocked device). 4 Rated values An s.r.c.d. shall be rated in terms of the following: a) rated tripping current (I o%N ) (see2.5); b) rated non-tripping current (I %N ) (see2.6); c) rated current of the s.r.c
44、.d. (I N ) (see2.7); d) rated voltage (U N ) (see2.9); e) rated earth fault breaking capacity (see2.10); f) rated frequency (see2.11). 5 Marking and labelling 5.1 An s.r.c.d. shall be marked legibly and in a durable manner with the following particulars: a) rated voltage; b) rated current; c) rated
45、tripping current; I current U voltage N rated o opened non-opened % residual (out-of-balance) a auxiliaryBS 7288:1990 4 BSI 04-1999 d) nature of supply and frequency, if other than50Hz; e) manufacturers or responsible vendors name or distinguishing mark; f) type reference where more than one type is
46、 manufactured; g) the number and date of this British Standard, i.e. BS7288:1990 1) h) the details concerning the operation of the test circuit on the s.r.c.d., including such words as “Test each time before use”; i) the closed and open positions (e.g. OFF/ON orO/I or both); j) the words “Supply Fau
47、lt” adjacent to the reverse polarity indicator, if fitted. 5.2 When symbols are used they shall be as follows: For the marking of the rated current and rated voltage of the s.r.c.d. figures may be used alone, the figures for the current rating being placed before or above that of the rated voltage a
48、nd separated by a line. The symbol for nature of supply shall be placed next to the marking for rated current and rated voltage. Examples are as follows: 5.3 The test details in5.1 c),h) andj) shall be visible when the s.r.c.d. is in normal use. All other markings shall be on any external surface un
49、less otherwise stated. 5.4 The terminals for the connection of the neutral and phase conductors shall be identified by the symbols, N and L respectively. 5.5 Terminals for the connection of protective conductors shall be marked with the symbol for earth. 5.6 Compliance with5.1 to5.5 shall be checked by inspection and by the tests of8.6. 5.7 An s.r.c.d. shall be provided with an instruction sheet for its use and the following information shall be included: a) a detailed procedure for testing before use arranged as a logical sequence of actions; b
