1、BSI Standards Publication BS ISO 8820-2:2014 Road vehicles Fuse-links Part 2: User guidelinesBS ISO 8820-2:2014 BRITISH STANDARD National foreword This British Standard is the UK implementation of ISO 8820-2:2014. It supersedes BS ISO 8820-2:2005 which is withdrawn. The UK participation in its prepa
2、ration was entrusted to Technical Committee AUE/16, Electrical and electronic equipment. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible f
3、or its correct application. The British Standards Institution 2014. Published by BSI Standards Limited 2014 ISBN 978 0 580 71425 2 ICS 43.040.10 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard was published under the authority of the Standards
4、Policy and Strategy Committee on 28 February 2014. Amendments issued since publication Date Text affectedBS ISO 8820-2:2014 ISO 2014 Road vehicles Fuse-links Part 2: User guidelines Vhicules routiers Liaisons fusibles Partie 2: Guide de lutilisateur INTERNATIONAL STANDARD ISO 8820-2 Third edition 20
5、14-02-15 Reference number ISO 8820-2:2014(E)BS ISO 8820-2:2014ISO 8820-2:2014(E)ii ISO 2014 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2014 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, elec
6、tronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel.
7、 + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in SwitzerlandBS ISO 8820-2:2014ISO 8820-2:2014(E) ISO 2014 All rights reserved iii Contents Page Foreword iv 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 Rated voltage and system voltag
8、e . 1 5 Rated current and continuous current 1 6 Cold resistance 1 7 Current and conductors 3 8 Current and contact resistance . 4 9 Current and ambient temperature 4 10 Cable protection versus time-current characteristics. 5 11 Selectivity . 7 12 Replacement of fuse-links 7 13 Voltage peaks during
9、opening of fuse-links . 7 14 Inrush withstand characteristics of fuse-links . 7 15 Electromagnetic compatibility (EMC) 8 Annex A (informative) Parameters for the selection of fuse-links in road vehicles 9 Annex B (normative) Selection criteria for fuse-links and cables 10BS ISO 8820-2:2014ISO 8820-2
10、:2014(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for
11、which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on al
12、l matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. T
13、his document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any
14、or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of use
15、rs and does not constitute an endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplement
16、ary information The committee responsible for this document is ISO/TC 22, Road vehicles, Subcommittee SC 3, Electrical and electronic equipment. This third edition cancels and replaces the second edition (ISO 8820-2:2005), which has been technically revised. ISO 8820 consists of the following parts,
17、 under the general title Road vehicles Fuse-links: Part 1: Definitions and general test requirements Part 2: User guidelines Part 3: Fuse-links with tabs (blade type) Type C (medium), Type E (high currents) and Type F (miniature) Part 4: Fuse-links with female contacts (Type A) and bolt-in contacts
18、(Type B) and their test fixtures Part 5: Fuse-links with axial terminals (Strip fuse-links) Types SF30 and SF51 and test fixtures Part 6: Single-bolt fuse-links Part 7: Fuse-links with tabs (Type G) with rated voltage of 450 V Part 8: Fuse-links with bolt-in contacts (Types H and J) with a rated vol
19、tage of 450 V Part 9: Fuse-links miniature low profile (Type K) Part 10: Road vehicles Fuse Part 10: Fuse-links with tabs Type L (high current miniature) 1) 1) To be published.iv ISO 2014 All rights reservedBS ISO 8820-2:2014INTERNATIONAL ST ANDARD ISO 8820-2:2014(E) Road vehicles Fuse-links Part 2:
20、 User guidelines 1 Scope This part of ISO 8820 gives guidance for the choice and application of automotive fuse-links which are defined in the other parts of this International Standard. It describes the various parameters which have to be taken into account when selecting fuse-links. Fuse-links acc
21、ording to ISO 8820 are intended for electrical cable protection. If these types of fuse-links are to be used for electrical component protection, it should be agreed between customer and supplier. It is intended to be used in conjunction with the other parts of ISO 8820. 2 Normative references The f
22、ollowing documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 8820-1,
23、Road vehicles Fuse-links Part 1: Definitions and general test requirements 3 T erms a nd definiti ons For the purposes of this document, the terms and definitions in ISO 8820-1 apply. 4 Rated voltage and system voltage The fuse rated voltage shall always be higher than the nominal voltage of the ele
24、ctrical system of the vehicle to allow for possible overvoltage conditions. 5 Rated current and continuous current The rated current (I R ) is the current used for identifying the fuse-link. The continuous current (I C ) in Figure 1 is the maximum current flowing continuously through the circuit (fu
25、se-link, terminals, holder, and cables) at a maximum ambient temperature. The continuous current is lower than the rated current. 6 Cold resistance The cold resistance is the resistance of a fuse-link without self-heating at room temperature (RT). It can be calculated by the drop voltage measured, b
26、etween the measuring points of the fuse-link (specified in the appropriate part of ISO 8820 according to the type of the fuse), at a certain current, typically measured at 10 % of fuse rated current. The spread of fuse-link cold resistance due to volume production results in a spread in power dissip
27、ation and a spread in time-current characteristic (see Figure 2). ISO 2014 All rights reserved 1BS ISO 8820-2:2014ISO 8820-2:2014(E) Figures 2 and 3 show the variation of operating time and voltage drop versus cold resistance for a given test current. Key Y operating time (t) X current (I) 1 time-cu
28、rrent characteristic Figure 1 Rated current, continuous current, and time-current characteristic The rise of the temperature in the circuit depends on the current and time. Key Y operating time X cold resistance Figure 2 Cold resistance versus operating time2 ISO 2014 All rights reservedBS ISO 8820-
29、2:2014ISO 8820-2:2014(E) Key Y voltage drop X cold resistance Figure 3 Cold resistance versus voltage drop 7 Current and conductors The temperature rise of a conductor is a function of current, conductor cross section, and time duration. For system application, other influences, e.g. ambient tempera
30、ture, conducting and isolating material, strands, have to be taken into account also. Figure 4 shows stabilized temperature rise for various conductor cross sections. ISO 2014 All rights reserved 3BS ISO 8820-2:2014ISO 8820-2:2014(E) Key Y conductor temperature X conductor session section X current
31、(I) Figure 4 Conductor temperatures for different conductor cross sections versus current 8 Current and contact resistance A higher contact resistance of mated terminals leads to a temperature rise and reduced thermal conduction from the fuse-link. The temperature of the fuse-link terminal will incr
32、ease and the continuous current for the application has to be derated. A temperature rise test can be conducted using fuse-links, fuse holders, and connections as specified by the vehicle manufacturer. At a specified test current, the temperature of the connections shall be measured at the points sp
33、ecified in the appropriate part of the ISO 8820 according to the type of the fuse. After thermal equilibrium has been achieved, the temperature rise of the connection shall not exceed the limits as specified for terminals and cable. 9 Current and ambient temperature All components of a circuit and t
34、heir parts have their own characteristic thermal curve as shown in Figure 5. Each component in a circuit has an upper temperature limit. An increase of temperature beyond this limit can result in increased resistance, which can by itself increase the temperature. As a result, the fuse-link can open.
35、4 ISO 2014 All rights reservedBS ISO 8820-2:2014ISO 8820-2:2014(E) Key Y current X ambient temperature 1 application area of the system 2 cable 3 connection 4 insulator 5 fuse element Figure 5 Maximum continuous currents of circuit components versus ambient temperature 10 Cable protection versus tim
36、e-current characteristics To ensure satisfactory cable protection, fuse-links shall be chosen such that they will always open before the maximum allowed cable temperature T maxis exceeded. Figure 6 shows the correct fuse- link selection. The maximum allowed temperature is never exceeded because abov
37、e a certain minimal fusing current (I f ), the fuse-link will open the circuit before the maximum permitted temperature of the cable is exceeded. ISO 2014 All rights reserved 5BS ISO 8820-2:2014ISO 8820-2:2014(E) Key Y cable temperature X current (I) Figure 6 Correct fuse selection Figure 7 shows in
38、correct fuse selection. The fuse-link allows some potentially damaging current to flow for too long, causing the cable to overheat. Key Y cable temperature X current (I) 1 unprotected region Figure 7 Incorrect fuse selection6 ISO 2014 All rights reservedBS ISO 8820-2:2014ISO 8820-2:2014(E) 11 Select
39、ivity It shall be ensured that higher level fuse-links do not open when lower level fuse-links are opening (see Figure 8). Key 1 battery 5 load 2 fuse-link level 1 a higher level 3 fuse-link level 2 b lower level 4 fuse-link level n NOTE Fuse-link level 1 is the highest level. Figure 8 Example for s
40、electivity 12 Replacement of fuse-links The replacement of fuse-links in a circuit shall be performed with the circuit de-energised. 13 Voltage peaks during opening of fuse-links When a fuse-link opens, voltage peaks can occur. The peaks can approach 10 times the rated voltage, depending on the load
41、 and the supply. 14 Inrush withstand characteristics of fuse-links In selecting a fuse-link, not only the continuous current and the rated current are to be considered but also the inrush characteristics of electrical devices. The inrush characteristic describes the time-current behaviour of electri
42、cal devices until the stabilized continuous current has been attained. ISO 2014 All rights reserved 7BS ISO 8820-2:2014ISO 8820-2:2014(E) It is important to consider the inrush characteristic as there are different requirements on the fuse-link depending on the type of load. The fuse-link shall with
43、stand the energy pulse caused by inrush without opening. 15 Electromagnetic compatibility (EMC) EMC tests for fuse-links are not required by this International Standard.8 ISO 2014 All rights reservedBS ISO 8820-2:2014ISO 8820-2:2014(E) Annex A (informative) Parameters for the selection of fuse-links
44、 in road vehicles The various parts of ISO 8820 define basic requirements and test methods for rated voltage, rated current, and time/current characteristics to give comparable and reproducible results of the fuse-links. In practice, however, there are other parameters to be considered for the corre
45、ct selection of fuse-links in road vehicles, for example: continuous current and operating time, fusing of one or more electrical/electronic devices, connection resistance, types of cables, e.g. different cross section, length, insulation, bundling, internal resistances of the fuse-links, terminals,
46、 cables, and devices, power dissipation of the components comprising the system, short-circuit parameters, inrush parameters of devices, stall current (of motors with locked rotors), different currents, voltages, and temperatures of the system and surroundings, fuse-link holders and boxes, orientati
47、on and location of the fuse-links, e.g. engine, passenger, luggage compartment, distances between the fuse-links in fuse boxes, environmental conditions (mechanical loads, climatic loads, chemical loads), cooling of fuse-links, e.g. by fan or through heat sink, and other aspects. NOTE Users are advi
48、sed to consult the manufacturers of fuse-links, terminals, and cables because not all of the above points can be addressed in this guide. ISO 2014 All rights reserved 9BS ISO 8820-2:2014ISO 8820-2:2014(E) Annex B (normative) Selection criteria for fuse-links and cables B.1 Introduction In any given
49、application, the characteristics of load, connecting cable, and fuse-link shall be carefully matched. This is necessary if the fuse-link is to provide the expected degree of protection in the event of an overcurrent in the circuit and to maintain that level of protection throughout the lifetime of the vehicle. The procedure that follows gives guidelines for selecting the correct size of cable and rated current of fuse-link. B.2 Selecting the corre
