IEC 60071-2

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Insulation co-ordination - Part 2: Application guideCoordination de l'isolement - Partie 2: Guide d'application29.080.01VSORãQRElectrical insulation in generalICS:Ta slovenski standard je istoveten z:IEC 60071-2SIST IEC 60071-2:1996en01-junij-1996SIST IEC 60071-2:1996SLOVENSKI
STANDARD
NORMEINTERNATIONALECEIIECINTERNATIONALSTANDARD71-2Troisième éditionThird edition1996-12Ó CEI 1996
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catalogueXFCoordination de l’isolement –Partie 2:Guide d’applicationInsulation co-ordination –Part 2:Application guideSIST IEC 60071-2:1996

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© IEC: 1996– 3 –CONTENTSPageFOREWORD.9Clause1General.111.1Scope.111.2Normative references.111.3List of symbols and definitions.132Representative voltage stresses in service.212.1Origin and classification of voltage stresses.212.2Characteristics of overvoltage protective devices.232.3Representative voltages and overvoltages.273Co-ordination withstand voltage.573.1Insulation strength characteristics.573.2Performance criterion.653.3Insulation co-ordination procedures.674Required withstand voltage.834.1General remarks.834.2Atmospheric correction.834.3Safety factors.875Standard withstand voltage and testing procedures.915.1General remarks.915.2Test conversion factors.935.3Determination of insulation withstand by type tests.956Special considerations for overhead lines.1036.1General remarks.1036.2Insulation co-ordination for operating voltages and temporary overvoltages.1036.3Insulation co-ordination for slow-front overvoltages.1056.4Insulation co-ordination for lightning overvoltages.1057Special considerations for substations.1077.1General remarks.1077.2Insulation co-ordination for overvoltages.111Tables1Recommended creepage distances.712Test conversion factors for range I, to convert required switching impulses withstand voltages to short-duration power-frequency and lightning impulse withstand voltages.933Test conversion factors for range II to convert required short-duration power-frequencywithstand voltages to switching impulse withstand voltages.954Selectivity of test procedures B and C of IEC 60-1.99A.1Correlation between standard lightning impulse withstand voltages and minimum airclearances.119A.2Correlation between standard switching impulse withstand voltages andminimum phase-to-earth air clearances.121A.3Correlation between standard switching impulse withstand voltages andminimum phase-to-phase air clearances.121C.1Breakdown voltage versus cumulative flashover probability – Single insulationand 100 parallel insulations.135SIST IEC 60071-2:1996

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© IEC: 1996– 5 –F.1Corona damping constant Kco.175F.2Factor A for various overhead lines.185G.1Typical gap factors K for switching impulse breakdown phase-to-earth.195G.2Gap factors for typical phase-to-phase geometries.197H.1Summary of minimum required withstand voltages obtained for example H.1.1.213H.2Summary of required withstand voltages obtained for example H.1.2.217H.3Values related to the insulation co-ordination procedure for example H.3.249Figures1Range of 2 % slow-front overvoltages at the receiving end due to line energizationand re-energization.392Ratio between the 2 % values of slow-front overvoltages phase-to-phase andphase-to-earth.413Diagram for surge arrester connection to the protected object.554Distributive discharge probability of self-restoring insulation describedon a linear scale.735Disruptive discharge probability of self-restoring insulation describedon a Gaussian scale.736Evaluation of deterministic co-ordination factor Kcd.757Evaluation of the risk of failure.778Risk of failure of external insulation for slow-front overvoltages as a function ofthe statistical co-ordination factor Kcs.819Dependence of exponent m on the co-ordination switching impulse withstand voltage.8710Probability P of an equipment to pass the test dependent on the difference Kbetween the actual and the rated impulse withstand voltage.9911Example of a schematic substation layout used for the overvoltage stress location(see 7.1).107B.1Earth-fault factor k on a base of X0/X1 for R1/X1 = R = 0.125B.2Relationship between R0/X1 and X0/X1 for constant values of earth-fault factor kwhere R1 = 0.125B.3Relationship between R0/X1 et X0/X1 for constant values of earth-fault factor kwhere R1 = 0,5 X1.127B.4Relationship between R0/X1 et X0/X1 for constant values of earth-fault factor kwhere R1 = X1.127B.5Relationship between R0/X1 et X0/X1 for constant values of earth-fault factor kwhere R1 = 2X1.129C.1Conversion chart for the reduction of the withstand voltage due to placing insulationconfigurations in parallel.139D.1Example for bivariate phase-to-phase overvoltage curves with constant probabilitydensity and tangents giving the relevant 2 % values.151D.2Principle of the determination of the representative phase-to-phase overvoltage Upre.153D.3Schematic phase-phase-earth insulation configuration.153D.4Description of the 50 % switching impulse flashover voltage of a phase-phase-earthinsulation.155SIST IEC 60071-2:1996

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© IEC: 1996– 7 –D.5Inclination angle of the phase-to-phase insulation characteristic in range b dependenton the ratio of the phase-phase clearance D to the height Ht above earth.157E.1Distributed capacitances of the windings of a transformer and the equivalent circuitdescribing the windings.169E.2Values of factor J describing the effect of the winding connections on the inductivesurge transference.171AnnexesAClearances in air to assure a specified impulse withstand voltage installation.115BDetermination of temporary overvoltages due to earth faults.123CWeibull probability distributions.131DDetermination of the representative slow-front overvoltage due to line energizationand re-energization.141ETransferred overvoltages in transformers.159FLightning overvoltages.173GCalculation of air gap breakdown strength from experimental data.187HExamples of insulation co-ordination procedure.199JBibliography.251SIST IEC 60071-2:1996

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© IEC: 1996– 9 –INTERNATIONAL ELECTROTECHNICAL COMMISSION––––––––––INSULATION CO-ORDINATION –Part 2: Application guideFOREWORD1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprisingall national electrotechnical committees (IEC National Committees). The object to the IEC is to promoteinternational cooperation on all questions concerning standardization in the electrical and electronic fields. Tothis end and in addition to other activities, the IEC publishes International Standards. Their preparation isentrusted to technical committees; any IEC National Committee interested in the subject dealt with mayparticipate in this preparatory work. International, governmental and non-governmental organizations liaisingwith the IEC also participate in this preparation. The IEC collaborates closely with the International Organizationfor Standardization (ISO) in accordance with conditions determined by agreement between the twoorganizations.2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible aninternational consensus of opinion on the relevant subjects since each technical committee has representationfrom all interested National Committees.3) The documents produced have the form of recommendations for international use and are published in the formof standards, technical reports or guides and they are accepted by the National Committees in that sense.4) In order to promote international unification, IEC National Committees undertake to apply IEC InternationalStandards transparently to the maximum extent possible in their national and regional standards. Anydivergence between the IEC Standard and the corresponding national or regional standard shall be clearlyindicated in the latter.5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for anyequipment declared to be in conformity with one of its standards.6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subjectof patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.International Standard IEC 71-2, has been prepared by IEC technical committee 28: Insulationco-ordination.This third edition cancels and replaces the second edition published in 1976 and constitutes atechnical revision.The text of this standard is based on the following documents:FDISReport on voting28/115/FDIS28/117/RVDFull information on the voting for the approval of this standard can be found in the report onvoting indicated in the
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