1、BRITISH STANDARD CONFIRMED AUGUST1978 BS714:1950 Incorporating Amendment No. 1 Specification for Cartridge fuse-links foruse in railway-signalling circuitsBS714:1950 This British Standard, having been approved by the Electrical Industry Standards Committee and endorsed by the chairman ofthe Engineer
2、ing Divisional Council, was published under theauthority of the General Council on 30 November1950 BSI 12-1999 First published November1936 First revision November1950 ISBN 0 580 00789 8 Co-operating organizations The Electrical Industry Standards Committee, under whose supervision this British Stan
3、dard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Admiralty Air Ministry Association of Consulting Engineers (Incorporated) Association of Supervising Electrical Engineers British Electrical and Allied Industries Res
4、earch Association British Electrical and Allied Manufacturers Association* British Electrical Development Association British Railways* British Electricity Authority and Area Boards Cable Makers Association Electric Lamp Manufacturers Association Electric Light Fittings Association Electrical Contra
5、ctors Association (Incorporated) Electrical Contractors Association of Scotland Engineering Equipment Users Association General Post Office Institution of Electrical Engineers* Ministry of Fuel and Power Ministry of Labour and National Service (Factory Department) Ministry of Supply Ministry of Work
6、s National Physical Laboratory North of Scotland Hydro-Electric Board Public Transport Association (Incorporated) Radio Industry Council The Government department and scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represe
7、nted on the Committee entrusted with the preparation of this British Standard: Crown Agents for the Colonies Federation of British Industries Ministry of Transport Office of the High Commissioner for India Office of the High Commissioner for New Zealand Individual manufacturers of Railway Signalling
8、 Apparatus Amendments issued since publication Amd. No. Date of issue Comments 1566 February 1953 Indicated by a sideline in the marginBS714:1950 BSI 12-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Standard current ratings 1 4 Dimensions
9、1 5 Manufacture 2 6 End caps 2 7 Marking 2 8 Type tests 2 9 Acceptance tests 3 Appendix Information to be supplied by the purchaser 4 Figure 1 Dimensions for standard cartridge fuse 4 Figure 2 Arrangement for test for breaking capacity 4 Figure 3 Assembly of test clips 5 Figure 4 Standard graph pape
10、r for time-current characteristics 6 Table 1 Potential-drop at current rating 3 Table 2 Operational characteristics of fuses 3BS714:1950 ii BSI 12-1999 Foreword This British Standard, first issued in1936, has now been revised in order to bring the range of fuses concerned into line with modern devel
11、opments 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 interchangeable in fuses of different types without alteration of the characteristics of the fuses. For th
12、e 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 drawn up to apply to cartridge fuse-links only. Discrimination between fuse-links of different curren
13、t 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 of fuses is dealt with in BS88, “Electric fuses, low-voltage and medium-voltage”, where more gene
14、ral 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 with a British Standard does not of itself confer immunity from legal obligations. Summary of page
15、s This document comprises a front cover, an inside front cover, pagesi andii, pages1 to6 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.BS714:1950 BSI 12-1999 1 1
16、Scope This British Standard covers fuse-links suitable for use in railway-signalling circuits in which the declared voltage does not exceed250 volts between conductors or between conductor and earth. The standard lays down standard current ratings and standard dimensions; it deals with manufacturing
17、 requirements, end caps, marking, performance and the type 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 car
18、tridge containing a fuse-element 2.2 cartridge a totally-enclosing 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
19、fuse a current stated by the manufacturer as the current that 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
20、circuit when the circuit is equipped for the insertion of 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 cur
21、rent the minimum current at which the fuse-element will melt 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
22、rating of a fuse the voltage stated by the manufacturer as 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 a
23、rcing time the time between the end of the pre-arcing time 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 tim
24、e and the end of the arcing time; sometimes called “blowing” 3 Standard current ratings The standard current ratings shall be3,5,10,15,20 and30 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
25、the diameter of the end cap. Overall length 2 0.040in. Cap diameter 9 / 16 0.015in. Length of cap not less than 3 / 8in. and not greater than 7 / 16 in. minimum fusing-current current rating -BS714:1950 2 BSI 12-1999 5 Manufacture The material used in manufacture shall be such as to have no deleteri
26、ous 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 of non-ignitable, non-hygroscopic insulating material. The joints between the fuse
27、-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 caps The fuse shall be capped at both ends with copper caps, the thickness of metal be
28、ing not less than22 S.W.G.(0.028in. 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, and parallel with the centre-line of the cartridge. If tinning is required by the pur
29、chaser 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 the fuse, applied round the fuse at one end adjacent to the cap. Colours corresponding
30、 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 rating. iii) Carrying capacity 1)in amperes. iv) The number of this British Standard, v
31、iz. BS714. 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 current rating (i.e.,thirty-six fuses in all), identical in all essential respects with those
32、 purchased. b) Accelerated life test. The fuses shall each carry a current equal to110per cent of the current rating for1000hours, and at no time during this period shall the temperature rise of the hottest accessible portion of the assembly exceed40centigrade degrees. The fuses shall be mounted ver
33、tically in the standard test clips (see Figure 1) in an enclosure free from draughts, at normal room temperature not exceeding20 C. The cable connections to the clips shall be as specified in Figure 1, for the appropriate current rating of the fuse. At the conclusion of this test, the fuses shall be
34、 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 of500 amperes, and any lower value down to the minimum fusing current. The source of energy for the test
35、 shall be a secondary battery rated at not less than100ampere-hours on a one-hour rate of discharge, which shall be capable of giving the short-circuit current required, (i.e.,500amperes). The open circuit potential difference of the battery immediately prior to the test shall be260volts 2 per cent.
36、 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 required in accordance with a previous calibration of the circuit, with the fuse replaced by a link of n
37、egligible 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. Current rating Colour British Standard colour No. a amp. 3 5 10 15 20 30 Black White Sea green Azure b
38、lue Lemon Signal red 17 4 55 37 a See BS381C, “Colours for ready mixed paints”. 1) Appropriate current rating to be inserted.BS714:1950 BSI 12-1999 3 ii) Ignition of the fuse or attached apparatus. iii) Damage to the test clips sufficient to render them unserviceable without repair. d) Time-current
39、characteristics. When specified by the purchaser, the manufacturer shall submit time-current characteristics applicable to the complete range of fuses covered by this standard. The curves shall be plotted between time limits of0.01 second and1000 minutes in one graph to logarithmic scales on paper a
40、s shown in Figure 3. Tests may be carried out by the purchaser 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 ti
41、mes shall be within the limits represented by lines drawn 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
42、. When specified by the purchaser, the manufacturer shall 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 n
43、ot exceed 5 per cent. 9 Acceptance tests a) When required, 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 Clause8 a) and the
44、fuses for testing purposes shall be selected at random from the complete consignment. b) For the purpose of these tests the fuses shall be mounted vertically in the standard test clips (seeFigure 1) in an enclosure free from draughts, at normal room temperature not exceeding20 C. The cable connectio
45、ns to the clips shall be as shown in Figure 1, for the 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
46、. The reading shall be taken when a steady value has 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 (seeClause3) in a time not greater than that shown in Table 2 for the appropriate cu
47、rrent 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 fuses selected for test purposes shall be inspected to ensure that they comply with
48、the conditions specified in Clauses4, 5, 6 and7. ii) If more than one of the six fuses selected for test purposes fails to satisfy the tests laid down, the consignment of fuses of the current rating concerned shall be liable to rejection as not complying with the standard. If one of the six fuses of
49、 each current rating selected for test purposes fails to comply with the standard in any respect, another complete set of tests may be carried out on a further six fuses of the current rating concerned and unless all these are completely satisfactory the consignment of this rating shall be liable to rejection. iii) The fusing factor, as defined in Clause2.8, shall be not greater than2.0. Current rating Potential-drop amp. 3 5 10 and over mv. 400 300 200 Current rating
