IEC_60408-1985_scan.pdf

4COMMISSION ELECTROTECHNIQUE INTERNATIONALENORME DE LA CEIINTERNATIONAL ELECTROTECHNICAL COMMISSIONIEC STANDARDPublication 408Deuxieme edition-Second edition1985Interrupteurs a basse tension dans Iair,sectionneurs a bassetension dans lair,interrupteurs-sectionneurs a basse tensiondans Iair et combins a fusibles a basse tensionLow-voltage air-break switches,air-break disconnectors,air-break switch-disconnectors and fuse-combination unitsCEI1985Droits de reproduction reserves-Copyright-all rights reservedAucune partie de cette publication ne peut tre reproduite niutilise sous quelque No part of this publication may be reproduced or unilized in any form or by any means.forme que ce soit et par aucun procede,electronique ou mecanique,y compris la elecronic or mechanical,including photocopying and microfilm,without permissionphotocopie et les microfilms,sans laccord ecrit de Iediteur.in writing from the publisher.Bureau Central de la Commission Electrotechnique Internationale3,rue de VarembeGeneve,SuissePrixIECPrice Frs.96.-VOL.q408IEC1985一3一CONTENTSPageFOREWORD,5PREFACES.5Clause1.General.1.1 Scope.1.2 Object.772.Definitions.73.Classification154.Characteristics of equipment.174.1 Summary of characteristics.174.2 Type of equipment174.3 Rated values.74.4 Auxiliary circuits295.Markings296.Standard conditions for operation in service.6.1 Normal service conditions.31317.Standard conditions for construction.7.1 Mechanical design3337.2 Enclosures.7.3 Temperature rise7.4 Dielectric properties.377.5 Operating conditions397.6 Additional safety requirements for disconnectors and switch-disconnectors.398.Tests.418.1 Verification of the characteristics of equipment.,82 Type tests4383 Routine tests.69APPENDIX A-Information to be given by the user when conditions for operation in service73differ from the standard.,.,.APPENDIX B-Clearances and creepage distances.,75APPENDIX C-Equipment for direct switching of individual motors.77FIGURES88408CIEC 19855INTERNATIONAL ELECTROTECHNICAL COMMISSIONLOW-VOLTAGE AIR-BREAK SWITCHES,AIR-BREAK DISCONNECTORS,AIR-BREAK SWITCH-DISCONNECTORSAND FUSE-COMBINATION UNITSFOREWORD1)The formal decisions or agreements of the IEC on technical matters,prepared by Technical Committees on which allthe National committees having a special interest therein are represented,express,as nearly as possible,an internationalconsensus of opinion on the subjects dealt with.2)They have the form of recommendations for international use and they are accepted by the National Committees in thatsense.3)In order to promote international unification,the IE C expresses the wish that all National Committees should adoptthe text of the IEC Recommendation for their national rules in so far as national conditions will permit.Any divergencebetween the I EC Recommendations and the corresponding national rules should,as far as possible,be clearly indicatedin the latter.PREFACE TO THE FIRST EDITIONThis Recommendation has been prepared by Sub-Committee 17B,Low-Voltage Switchgear and Controlgear,of IECTechnical Committee No.17,Switchgear and Controlgear.Work was commenced in January 1969;two other drafts were elaborated in October 1969 and November 1970.As aresult of the meeting held in Brussels in 1971,a final draft was submitted to the National Committees for approval underthe Six Months Rule in November 1971.The following countries voted explicitly in favour of publication:AustraliaPolandAustriaPortugalBelgiumRomaniaCzechoslovakiaSouth AfricaDenmarkSwedenFranceSwitzerlandGermanyTurkeyIsraelUnion of SovietItalySocialist RepublicsJapanUnited KingdomNetherlandsUnited States of AmericaNorwayYugoslaviaPREFACE TO THE SECOND EDITIONThis standard has been prepared by Sub-Committee 17B:Low-voltage Switchgear and Controlgear,of IEC TechnicalCommittee No.17:Switchgear and Controlgear.This second edition is based on the first edition,1972,Amendment No.1,1979 and Amendment No.2,1983.408CIEC19857LOW-VOLTAGE AIR-BREAK SWITCHES,AIR-BREAK DISCONNECTORS,AIR-BREAK SWITCH-DISCONNECTORSAND FUSE-COMBINATION UNITS1.General1.1 ScopeThis standard applies to air-break switches,air-break disconnectors,air-break switch-disconnectors and fuse-combination units to be used in distribution circuits and motor circuitsthe rated voltage of which does not exceed 1000 V a.c.or 1 200 V d.c.Notes 1.-Depending on its design,a switch(or disconnector)can be referred to as rotary switch(disconnector),cam-operated switch(disconnector),knife-switch(disconnector),etc.2.-If they are not manually operated,switches and disconnectors may have to comply with additionalrequirements.Any fuses incorporated shall conform to the requirements laid down in the relevant IECfuse standards.This standard does not apply to equipment coming within the scope of IEC Publication157-1:Circuit-breakers,IEC Publication 158-1:Contactors,IEC Publication 292-1:MotorStarters,and IEC Publication 337-1:Control Switches;however,when switches and fuse-combination units coming into the scope of this standard are normally used to start,accelerateand/or stop a motor,they shall also comply with the additional requirements given inAppendix C.This standard does not include the additional requirements necessary for electrical appara-tus for explosive gas atmospheres.Notes 3.-In this standard,the word switch also applies to the apparatus referred to in French as commuta-teurs,intended to modify the connections between several circuits,and inter alia to substitute onepart of a circuit for another.4.-As a general rule,in the rest of this standard,switches,disconnectors,switch-disconnectors and fuse-combination units will be referred to as equipment.1.2 ObjectThe object of this standard is to state:1)the characteristics of the equipment;2)the conditions with which the equipment must comply with reference to:a)operation and behaviour in normal service,b)operation and behaviour in case of specified abnormal conditions,e.g.short circuit;c)dielectric properties;3)the tests intended for confirming that these conditions have been met and the methods tobe adopted for these tests;4)the data to be marked on the equipment.2.DefinitionsFor the purpose of this standard,the following definitions shall apply:408IEC198592.1 Devices2.1.1 Switching deviceA device designed to make or break the current in one or more electric circuits.2.1.2 Mechanical switching deviceA switching device designed to close and open one or more electric circuits by means ofseparable contacts.2.1.3 Switch(mechanical)A mechanical switching device capable of making,carrying and breaking currents undernormal circuit conditions which may include specified operating overload conditions and alsocarrying for a specified time currents under specified abnormal circuit conditions such as thoseof short circuit.Note.-A switch may also be capable of making,but not breaking,short-circuit currents.2.1.4 Disconnector(isolator)A mechanical switching device which,for reasons of safety,provides in the open positionan isolating distance in accordance with specified requirements.A disconnector is capable of opening and closing a circuit when either negligible currentis broken or made,or when no significant change in the voltage across the terminals of eachof the poles of the disconnector occurs.It is also capable of carrying currents under normalcircuit conditions and carrying for a specified time currents under abnormal conditions suchas those of short circuit.Notes 1.-Negligible currentsimply currents such as the capacitance currents of bushings,busbars,connections,very short lengths of cables and currents of voltage transformers and dividers.No significant change in voltagerefers to such applications as the by-passing of induction voltageregulators or circuit-breakers.2.-There are devices,referred to in this standard as disconnectors,which possess a certain making and/orbreaking capacity.2.1.5 Switch-disconnector(switch-isolator)A switch which,in the open position,satisfies the isolating requirements specified for adisconnector.2.1.6 FuseA switching device that,by the melting of one or more of its specially designed andproportioned components,opens the circuit in which it is inserted and breaks the current whenthis exceeds a given value for a sufficient time.Note.-The fuse comprises all the parts that form the complete switching device.2.1.7 Fuse-combination unitA combination of a switch,a disconnector or a switch-disconnector and one or more fusesin a composite unit,made by the manufacturer or in accordance with his instructions.2.1.8 Switch-fuseA switch in which one or more poles have a fuse in series in a composite unit.2.1.9 Disconnector-fuseA disconnector in which one or more poles have a fuse in series in a composite unit.2.1.10 Fuse-switchA switch in which a fuse-link or a fuse carrier with fuse-link forms the moving contact ofthe switch.