1、BSI Standards PublicationBS ISO 10924-2:2014Road vehicles CircuitbreakersPart 2: Users guideBS ISO 10924-2:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 10924-2:2014.The UK participation in its preparation was entrusted to TechnicalCommittee AUE/16, Elec
2、trical and electronic equipment.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution
3、 2014. Published by BSI StandardsLimited 2014ISBN 978 0 580 69311 3ICS 43.040.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 28 February 2014.Amendments issued
4、since publicationDate Text affectedBS ISO 10924-2:2014 ISO 2014Road vehicles Circuit breakers Part 2: Users guideVhicules routiers Coupe-circuits Partie 2: Guide de lutilisateurINTERNATIONAL STANDARDISO10924-2First edition2014-02-15Reference numberISO 10924-2:2014(E)BS ISO 10924-2:2014ISO 10924-2:20
5、14(E)ii ISO 2014 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2014All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or a
6、n 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 officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPub
7、lished in SwitzerlandBS ISO 10924-2:2014ISO 10924-2:2014(E) ISO 2014 All rights reserved iiiContents PageForeword iv1 Scope . 12 Normative references 13 Terms and definitions . 14 General 14.1 Circuit breaker nominal voltage. 24.2 Supply voltage maximum (Usmax) 24.3 Rated current (IR) and continuous
8、 current 25 Current and conductors (cables) . 36 Current and contact resistance . 47 Current and ambient temperature 48 Cable protection: temperature versus current characteristics . 59 Selectivity . 710 Replacement of circuit breakers 811 Voltage peaks during opening of circuit breakers 812 Inrush
9、withstand characteristics of circuit breakers . 813 Electromagnetic compatibility (EMC) 9Annex A (informative) Selection procedure for circuit breakers and cables 10Annex B (informative) Selection of circuit breakers .24Annex C (informative) Ambient temperature influence25BS ISO 10924-2:2014ISO 1092
10、4-2:2014(E)ForewordISO (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 a
12、ll 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 - Supplementa
16、ry information/TC 22, Road vehicles, Subcommittee SC 3, Electric and electronic equipment.ISO 10924 consists of the following parts, under the general title Road vehicles Circuit breakers: Part 1: Definitions and general test requirements Part 2: Users guide Part 4: Medium circuit breakers with tabs
17、 (Blade type), Form CB15The following parts are under preparation: Part 3: Miniature circuit breakers Part 5: Circuit breakers with tabs with rated voltage of 450 Viv ISO 2014 All rights reservedBS ISO 10924-2:2014INTERNATIONAL STANDARD ISO 10924-2:2014(E)Road vehicles Circuit breakers Part 2: Users
18、 guide1 ScopeThis part of ISO 10924 gives guidance for the choice and application of automotive circuit breakers. It describes the various parameters which have to be taken into account when selecting circuit breakers.2 Normative referencesThe following documents, in whole or in part, are normativel
19、y 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, Road vehicles Fuse-links Part 1: Definitions and general
20、 test requirementsISO 10924-1, Road vehicles Circuit breakers Part 1: Definitions and general test requirementsISO 16750-1, Road vehicles Environmental conditions and testing for electrical and electronic equipment Part 1: GeneralISO 16750-2, Road vehicles Environmental conditions and testing for el
21、ectrical and electronic equipment Part 2: Electrical loads3 Terms and definitionsFor the purposes of this document, the terms and definitions in ISO 8820-1 and ISO 10924-1 and the following apply.4 GeneralThe various parts of ISO 10924 define basic requirements and test methods for nominal voltage,
22、rated current, IR, and time/current characteristics to give comparable and reproducible results of circuit breakers.In practice, however, there are other parameters to be considered for the correct selection of circuit breakers in road vehicles, such as continuous current, operating time, overload p
23、rotection of one or more electrical/electronic devices, connection resistance, types of cables, e.g. different cross section, length, insulation, bundling, internal resistances (voltage drop) of the circuit breakers, contacts, cables, and devices, power dissipation of the components comprising the s
24、ystem, ISO 2014 All rights reserved 1BS ISO 10924-2:2014ISO 10924-2:2014(E) short-circuit parameters, inrush parameters of devices, operating mode of the load, operating of one or more electrical/electronic devices, orientation and location of the circuit breakers, e.g. engine, passenger or luggage
25、compartment, different currents, voltages, and temperatures of the system and surroundings, distances or clearances inside circuit breaker boxes or holders, different circuit breakers, circuit breaker holders and boxes (see Annex B), environmental conditions (mechanical loads, climatically loads, ch
26、emical loads), and forced cooling of the circuit breakers.NOTE Users are advised to consult the manufacturers of circuit-breaker, contacts and cables, because not all of the above points can be addressed in this guide.The parameters listed are not intended to cover all the possible parameters that n
27、eed to be taken into consideration for circuit breaker selection nor is it intended that all parameters will need to be considered in each vehicle applications.4.1 Circuit breaker nominal voltageSee ISO 16750-14.2 Supply voltage maximum (Usmax)See ISO 16750-24.3 Rated current (IR) and continuous cur
28、rentThe rated current (IR) is the current used for identifying the circuit breaker.The continuous current (IC) in Figure 1 is the maximum current which the circuit can continuously carry under specified conditions: ambient temperature (23 C), duration maximum 1 h, standard test holder, cross section
29、s of wires. The continuous current can be lower than the rated current, IR.See A.2.2.32 ISO 2014 All rights reservedBS ISO 10924-2:2014ISO 10924-2:2014(E)KeyX current, IY operating time, tICcontinuous currentIRrated currentFigure 1 Rated current (IR), continuous current, and time-current characteris
30、tic5 Current and conductors (cables)The temperature rise of a cable is a function of current, conductor cross-section, strands, insolating materials time duration, and ambient temperature.See A.2.2.4Figure 2 shows stabilized temperature rise for various conductor cross sections at RT. ISO 2014 All r
31、ights reserved 3BS ISO 10924-2:2014ISO 10924-2:2014(E)KeyX1 current, IX2 conductor cross sectionY conductor temperature, TFigure 2 Conductor temperatures for different conductor cross sections vs. current at RT6 Current and contact resistanceA higher resistance of mated terminals will result in a te
32、mperature rise and reduced thermal conduction away from the circuit breaker. Hence, the temperature of the circuit breaker terminal will be higher and the continuous current for the application lower.A temperature rise test can be conducted using circuit breakers, circuit breaker holders and connect
33、ions as specified by the vehicle manufacturer. At a specified test current, the temperature of the connections shall be measured at the points, either tabs or bolt connection of the circuit breaker that protrude from the base of the circuit breaker body (specified in the appropriate part of the ISO
34、10924 according to the type of the circuit breaker). After thermal equilibrium has been achieved, the temperature rise of the connection shall not exceed the limits specified for terminals and cable.7 Current and ambient temperatureAll components of a circuit and their parts have their own character
35、istic curve as shown in Figure 3.Each component in a circuit has an upper temperature limit. An increase of temperature results in increased resistance, which can increase the temperature by itself. As a result, the circuit breaker can trip. It is always recommended to consult with specific manufact
36、urers of circuit breakers for current versus temperature curves as both design and thermal materials used result in different curve characteristics.See A.2.2.4 and Annex C4 ISO 2014 All rights reservedBS ISO 10924-2:2014ISO 10924-2:2014(E)KeyX ambient temperature, TY current, I1 application area2 ca
37、ble3 connection4 insulator5 circuit breakerFigure 3 Maximum continuous currents of circuit components vs. ambient temperature8 Cable protection: temperature versus current characteristicsTo ensure satisfactory cable protection, circuit breakers shall be chosen such that they will always open before
38、the maximum allowed cable temperature, Tmax,exceeds. Figure 4 shows the correct circuit breaker selection. The maximum allowed temperature never exceeds, because above a certain minimal operating current (If), the circuit breaker will trip before the maximum permitted temperature of the cable exceed
39、s.See Annex A ISO 2014 All rights reserved 5BS ISO 10924-2:2014ISO 10924-2:2014(E)KeyX times rated currentY cable temperature, TIttrip currentTmaxmaximum allowed cable temperatureFigure 4 Correct circuit breaker selectionFigure 5 shows incorrect circuit breaker selection. The circuit breaker allows
40、some potentially damaging current to flow for too long, causing the cable to overheat.6 ISO 2014 All rights reservedBS ISO 10924-2:2014ISO 10924-2:2014(E)KeyX times rated currentY cable temperature, TIttrip currentTmaxmaximum allowed cable temperature1 unprotected regionFigure 5 Incorrect circuit br
41、eaker selection9 SelectivityIt shall be ensured that higher level circuit breakers do not trip when lower level circuit breakers are opening (see Figure 6). ISO 2014 All rights reserved 7BS ISO 10924-2:2014ISO 10924-2:2014(E)Key1 battery2 circuit breaker level 13 circuit breaker level 24 circuit bre
42、aker level n5 loadFigure 6 Example for a structure hierarchy10 Replacement of circuit breakersThe replacement of circuit breakers in a circuit shall be performed with the circuit de-energised.11 Voltage peaks during opening of circuit breakersDuring the opening process of the circuit breaker, voltag
43、e peaks can occur. The peaks can achieve six times the rated voltage, depending on the load and the supply.12 Inrush withstand characteristics of circuit breakersIn selecting a circuit breaker, not only the continuous current and the rated current, IR, are to be considered, but also the inrush chara
44、cteristics of electrical devices.The inrush characteristic describes the time-current behaviour of electrical devices until the stabilized continuous current has been attained.It is important to consider the inrush withstand characteristics as there are different requirements on the circuit breaker
45、depending on the type of load. The circuit breaker shall withstand the inrush energy without opening. If the inrush energy is either too high or too long, or a combination thereof, it can be necessary to select a higher rated circuit breaker to eliminate nuisance openings.See A.2.2.58 ISO 2014 All r
46、ights reservedBS ISO 10924-2:2014ISO 10924-2:2014(E)13 Electromagnetic compatibility (EMC)EMC test for circuit breakers are not required by this International Standard. ISO 2014 All rights reserved 9BS ISO 10924-2:2014ISO 10924-2:2014(E)Annex A (informative) Selection procedure for circuit breakers
47、and cablesA.1 IntroductionIn any given application, the characteristics of load, connecting cable, and circuit breaker should be carefully matched. This is necessary if the circuit breaker is to provide the expected degree of protection in the event of an overcurrent in the circuit and to maintain t
48、hat level of protection throughout the lifetime of the vehicle.KeyUNnominal voltage1 circuit breaker2 cable3 loadFigure A.1 Scheme of a generic circuit with a circuit breakerThe protection of a load in a vehicle electrical system is typically performed by a protection element close to the load. But
49、there are loads where the protection of the cable is also a sufficient protection for the load itself at the same time.Conventional cables consist in general of a copper-core and an insulation-layer. The copper-core heats up when the cable is exposed to current. If an overload occurs, the insulation-layer can be damaged or can even start to melt.There are three main reasons that can lead to this failure: the cross-section of the cable is too small to carry the current, wh
