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1、BRITISH STANDARD CONFIRMED AUGUST 1978 BS 714:1950 Incorporating Amendment No. 1 Specification for Cartridge fuse-links for use in railway-signalling circuits Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:21:01 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS
2、714:1950 This British Standard, having been approved by the Electrical Industry Standards Committee and endorsed by the chairman of the Engineering Divisional Council, was published under the authority of the General Council on 30 November 1950 BSI 12-1999 First published November 1936 First revisio
3、n November 1950 ISBN 0 580 00789 8 Co-operating 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: Admiralty Air Mini
4、stry Association of Consulting Engineers (Incorporated) Association of Supervising Electrical Engineers British Electrical and Allied Industries Research Association British Electrical and Allied Manufacturers Association* British Electrical Development Association British Railways* British Electric
5、ity Authority and Area Boards Cable Makers Association Electric Lamp Manufacturers Association Electric Light Fittings Association Electrical Contractors Association (Incorporated) Electrical Contractors Association of Scotland Engineering Equipment Users Association General Post Office Institution
6、of Electrical Engineers* Ministry of Fuel and Power Ministry of Labour and National Service (Factory Department) Ministry of Supply Ministry of Works National Physical Laboratory North of Scotland Hydro-Electric Board Public Transport Association (Incorporated) Radio Industry Council The Government
7、department 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: Crown Agents for the Colonies Federation of British Industries Ministry o
8、f Transport Office of the High Commissioner for India Office of the High Commissioner for New Zealand Individual manufacturers of Railway Signalling Apparatus Amendments issued since publication Amd. No.Date of issueComments 1566February 1953Indicated by a sideline in the margin Licensed Copy: Londo
9、n South Bank University, London South Bank University, Fri Dec 08 12:21:01 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 714:1950 BSI 12-1999i Contents Page Co-operating organizationsInside front cover Forewordii 1Scope1 2Definitions1 3Standard current ratings1 4Dimensions1 5Manufacture2 6End caps2
10、7Marking2 8Type tests2 9Acceptance tests3 Appendix Information to be supplied by the purchaser4 Figure 1 Dimensions for standard cartridge fuse4 Figure 2 Arrangement for test for breaking capacity4 Figure 3 Assembly of test clips5 Figure 4 Standard graph paper for time-current characteristics6 Table
11、 1 Potential-drop at current rating3 Table 2 Operational characteristics of fuses3 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:21:01 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 714:1950 ii BSI 12-1999 Foreword This British Standard, first issued in 1936
12、, has now been revised in order to bring the range of fuses concerned into line with modern developments in design and manufacture. In other British Standards, current ratings have been assigned only to fuses and not to cartridge fuse-links, because cartridge fuse-links are not necessarily interchan
13、geable in fuses of different types without alteration of the characteristics of the fuses. For the fuses dealt with in this standard, however, the influence of the surroundings of the cartridge fuse-links is small, the type of fuse holder being standard. This British Standard has therefore been draw
14、n up to apply to cartridge fuse-links only. Discrimination between fuse-links of different current rating has been dealt with as far as present experience permits, but the problem will continue to be investigated and any addition necessary to the standard will be made at a later date. A wider range
15、of fuses is dealt with in BS 88, “Electric fuses, low-voltage and medium-voltage”, where more general information is given. 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
16、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 6 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporate
17、d. This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:21:01 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 714:1950 BSI 12-19991 1 Scope This British Standard covers fuse-links suitable for
18、use in railway-signalling circuits in which the declared voltage does not exceed 250 volts between conductors or between conductor and earth. The standard lays down standard current ratings and standard dimensions; it deals with manufacturing requirements, end caps, marking, performance and the type
19、 tests required. The information to be supplied by a purchaser is stated in the Appendix. 2 Definitions For the purpose of this British Standard the following definitions shall apply: 2.1 cartridge fuse-link, (hereinafter called a fuse) a cartridge containing a fuse-element 2.2 cartridge a totally-e
20、nclosing fuse-element container consisting of insulating material, tubular in form and having its ends enclosed by metallic caps 2.3 fuse-element that part of a fuse which is designed to melt and thus open the circuit 2.4 current rating of a fuse a current stated by the manufacturer as the current t
21、hat the fuse will carry continuously without deterioration 2.5 prospective current of a circuit the current (the r.m.s. value of the alternating component of an alternating current, or the direct current) that would flow on the making of the circuit when the circuit is equipped for the insertion of
22、a fuse but the fuse is replaced by a link of negligible impedance 2.6 breaking-capacity rating of a fuse the greatest prospective current in a circuit which the fuse is capable of opening under the prescribed conditions 2.7 minimum fusing current the minimum current at which the fuse-element will me
23、lt in two hours, as determined from the time-current characteristic for the particular fuse rating 2.8 fusing factor of a fuse the ratio, greater than unity, of the minimum fusing-current to current-rating, namely: Fusing factor = 2.9 voltage rating of a fuse the voltage stated by the manufacturer a
24、s the highest declared voltage that may normally be associated with the fuse 2.10 pre-arcing time the time between the commencement of a current large enough to cause a break in a fuse-element and the instant when the break is initiated 2.11 arcing time the time between the end of the pre-arcing tim
25、e and the instant when the circuit is broken and the current becomes permanently zero 2.12 total operating time the sum of the pre-arcing time and the arcing time 2.13 operation of a fuse the process between the beginning of the pre-arcing time and the end of the arcing time; sometimes called “blowi
26、ng” 3 Standard current ratings The standard current ratings shall be 3, 5, 10, 15, 20 and 30 amperes. 4 Dimensions The dimensions (see also Figure 1) shall be as follows: The maximum diameter of the cartridge between the end caps shall be less than the diameter of the end cap. Overall length2 0.040
27、in. Cap diameter 9/16 0.015 in. Length of capnot less than 3/8 in. and not greater than 7/16in. minimum fusing-current current rating - Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:21:01 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 714:1950 2 BSI 12-1999
28、5 Manufacture The material used in manufacture shall be such as to have no deleterious action on any part of the fuse during its life, and this shall also apply under tropical conditions when the fuse is specified for use under such conditions. All non-metallic parts of the fuse shall be constructed
29、 of non-ignitable, non-hygroscopic insulating material. The joints between the fuse-element and the end caps shall be such that they shall not become disconnected before the fuse-element melts. The fuse-element shall be soldered or welded to the caps which make contact with the fuse clips. 6 End cap
30、s The fuse shall be capped at both ends with copper caps, the thickness of metal being not less than 22 S.W.G. (0.028 in. nominal). The caps shall be securely and rigidly fixed to the body of the cartridge and the ends of the caps shall be reasonably flat. The sides of the two caps shall be in line,
31、 and parallel with the centre-line of the cartridge. If tinning is required by the purchaser the caps shall be electro-tinned. 7 Marking Each fuse shall be clearly and indelibly marked in the following manner: a) By a band not less than “ in. wide, of the appropriate colour indicating the rating of
32、the fuse, applied round the fuse at one end adjacent to the cap. Colours corresponding to the standard current ratings shall be as follows: b) The following information shall also be marked on the fuse in a manner which will not interfere with the colour marking: i) Manufacturers name. ii) Voltage r
33、ating. iii) Carrying capacity1) in amperes. iv) The number of this British Standard, viz. BS 714. 8 Type tests a) The purchaser shall accept, as evidence of compliance with this British Standard, certificates of type tests, as specified below, of not less than six representative fuses of each curren
34、t rating (i.e., thirty-six fuses in all), identical in all essential respects with those purchased. b) Accelerated life test. The fuses shall each carry a current equal to 110 per cent of the current rating for 1 000 hours, and at no time during this period shall the temperature rise of the hottest
35、accessible portion of the assembly exceed 40 centigrade degrees. The fuses shall be mounted vertically in the standard test clips (see Figure 1) in an enclosure free from draughts, at normal room temperature not exceeding 20 C. The cable connections to the clips shall be as specified in Figure 1, fo
36、r the appropriate current rating of the fuse. At the conclusion of this test, the fuses shall be mechanically sound and the exterior shall show no sign of deterioration. c) Test for breaking capacity. The fuses shall each be capable of opening satisfactorily a circuit adjusted for a current of 500 a
37、mperes, and any lower value down to the minimum fusing current. The source of energy for the test shall be a secondary battery rated at not less than 100 ampere-hours on a one-hour rate of discharge, which shall be capable of giving the short-circuit current required, (i.e., 500 amperes). The open c
38、ircuit potential difference of the battery immediately prior to the test shall be 260 volts 2 per cent. The fuses shall be mounted in a suitable carrier and connected as indicated in Figure 2. The resistance R shall be non-inductive, and shall be adjusted to suit the value of short-circuit current r
39、equired in accordance with a previous calibration of the circuit, with the fuse replaced by a link of negligible impedance. A fuse-link shall be deemed not to comply with this standard if, during the test, any of the following phenomena occur: i) Holding of the arc for an appreciable length of time.
40、 Current ratingColour British Standard colour No.a amp. 3 5 10 15 20 30 Black White Sea green Azure blue Lemon Signal red 17 4 55 37 a See BS 381C, “Colours for ready mixed paints”. 1) Appropriate current rating to be inserted. Licensed Copy: London South Bank University, London South Bank Universit
41、y, Fri Dec 08 12:21:01 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 714:1950 BSI 12-19993 ii) Ignition of the fuse or attached apparatus. iii) Damage to the test clips sufficient to render them unserviceable without repair. d) Time-current characteristics. When specified by the purchaser, the manuf
42、acturer shall submit time-current characteristics applicable to the complete range of fuses covered by this standard. The curves shall be plotted between time limits of 0.01 second and 1 000 minutes in one graph to logarithmic scales on paper as shown in Figure 3. Tests may be carried out by the pur
43、chaser on a quantity of fuses as specified in a) above, and at points evenly distributed along the curves throughout the range of currents covered by the basic curves submitted. The fuses shall be mounted as specified in b) above. The fusing times shall be within the limits represented by lines draw
44、n one-third of the linear distance on the current scale from the curve of the fuse concerned to the curves applicable to fuses with current ratings immediately above or below the current rating of the fuse concerned. e) Declared cold resistance. When specified by the purchaser, the manufacturer shal
45、l submit declared cold resistance values at room temperature (20 C.) applicable to the current rating of the fuses. The variation in initial declared cold resistance of a quantity of fuses as specified in a) above at the same temperature shall not exceed 5 per cent. 9 Acceptance tests a) When requir
46、ed, facilities at the manufacturers works shall be provided to enable one or all of the following tests to be carried out at the discretion of the purchaser. The number of fuses subjected to each test shall be as laid down in Clause 8 a) and the fuses for testing purposes shall be selected at random
47、 from the complete consignment. b) For the purpose of these tests the fuses shall be mounted vertically in the standard test clips (see Figure 1) in an enclosure free from draughts, at normal room temperature not exceeding 20 C. The cable connections to the clips shall be as shown in Figure 1, for t
48、he appropriate current rating. c) Potential-drop at current rating. When a fuse is carrying its rated current, at room temperature (1520 C.), the potential-drop, measured between the end caps of the fuse, shall not exceed the values given in Table 1. The reading shall be taken when a steady value ha
49、s been reached. Table 1 Potential-drop at current rating d) Tests for operation. i) The fuse-element shall blow at a current equal to three times the current rating (see Clause 3) in a time not greater than that shown in Table 2 for the appropriate current rating. ii) The fuse-element shall carry, for at least one minute, the current equal to that shown in Table 2 for the appropriate current rating. Table 2 Operational characteristics of fuses e) General. i) The fuse
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