1、TECHNICAL REPORT IECTR 60664-2-2 First edition 2002-01 Insulation coordination for equipment within low-voltage systems Part 2-2: Interface considerations Application guide Reference number IEC/TR 60664-2-2:2002(E)Publication numbering As from 1 January 1997 all IEC publications are issued with a de
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7、ee below) for further information. Customer Service Centre If you have any questions regarding this publication or need further assistance, please contact the Customer Service Centre: Email: custserviec.ch Tel: +41 22 919 02 11 Fax: +41 22 919 03 00TECHNICAL REPORT IEC TR 60664-2-2 First edition 200
8、2-01 Insulation coordination for equipment within low-voltage systems Part 2-2: Interface considerations Application guide PRICE CODE IEC 2002 Copyright - all rights reserved No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including ph
9、otocopying and microfilm, without permission in writing from the publisher. International Electrotechnical Commission 3, rue de Varemb Geneva, Switzerland Telefax: +41 22 919 0300 e-mail: inmailiec.ch IEC web site http:/www.iec.ch F For price, see current catalogueCommission Electrotechnique Interna
10、tionaleInternational Electrotechnical Commission 2 TR 60664-2-2 IEC:2002(E) CONTENTS FOREWORD.3 INTRODUCTION.5 1 Scope.6 2 Reference documents.6 3 Definitions 7 4 Consideration of overvoltage categories.7 5 Consideration on the use of protective control 7 5.1 General .7 5.2 Recapitulation on lightni
11、ng overvoltages8 6 Observations on surge overvoltages and failure rates.9 6.1 General .9 6.2 Using field failure data.9 6.3 Preventing permanent damage10 7 Principles of coordination between SPDs and with equipment to be protected (refer also to IEC 61312-3) .11 8 Equipment for systems, installation
12、s and equipment operation under conditions of inherent or protective control 11 8.1 Specific protection for sections of systems or installations.11 8.2 Specific protection within equipment11 Bibliography12TR 60664-2-2 IEC:2002(E) 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ INSULATION COORDINATION
13、FOR EQUIPMENT WITHIN LOW-VOLTAGE SYSTEMS Part 2-2: Interface considerations Application guide FOREWORD 1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of t
14、he IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, the IEC publishes International Standards. Their preparation is entrusted to technical committees; any IEC National Co
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17、 from all interested National Committees. 3) The documents produced have the form of recommendations for international use and are published in the form of standards, technical specifications, technical reports or guides and they are accepted by the National Committees in that sense. 4) In order to
18、promote international unification, IEC National Committees undertake to apply IEC International Standards transparently to the maximum extent possible in their national and regional standards. Any divergence between the IEC Standard and the corresponding national or regional standard shall be clearl
19、y indicated in the latter. 5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with one of its standards. 6) Attention is drawn to the possibility that some of the elements of this technical report may be
20、 the subject of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights. The main task of IEC technical committees is to prepare International Standards. However, a technical committee may propose the publication of a technical report when it has collected
21、data of a different kind from that which is normally published as an International Standard, for example “state of the art”. Technical reports do not necessarily have to be reviewed until the data they provide are considered to be no longer valid or useful by the maintenance team. IEC 60664-2-2, whi
22、ch is a technical report, has been prepared by IEC technical committee 109: Insulation coordination for low-voltage equipment. The text of this technical report is based on the following documents: Enquiry draft Report on voting 28A/168/CDV 109/2/RVC Full information on the voting for the approval o
23、f this technical report can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 3. This document, which is purely informative, is not to be regarded as an International Standard. 4 TR 60664-2-2 IEC:2002(E) T
24、he committee has decided that the contents of this publication will remain unchanged until 2004. At this date, the publication will be reconfirmed, withdrawn; replaced by a revised edition, amended.TR 60664-2-2 IEC:2002(E) 5 INTRODUCTION This technical report provides guidelines for a common basis f
25、or IEC technical committees when considering interface issues in relation to insulation coordination. Surge protective devices are key elements in achieving a controlled overvoltage condition in low-voltage a.c. power systems and equipment. The aim of this guide is to avoid conflicting activities in
26、 the various committees involved and to achieve consistent requirements and guidelines. It deals with factors that influence the determination of overvoltage categories for installation and equipment. A technical report IEC TR 62066 is being prepared by a joint working group (JWG) initially composed
27、 of representatives from the five IEC technical committees and subcommittees listed below and subsequently complemented by experts appointed by national committees and by CIGRE-CIRED. SC 37A Low-voltage surge-protective devices TC 64 Electrical installations and protection against electric shock SC
28、77B High-frequency phenomena TC 81 Lightning protection TC 109 Insulation coordination for low-voltage equipment Excerpts from IEC 62066 are included in order to identify information relevant to insulation coordination for low-voltage equipment. 6 TR 60664-2-2 IEC:2002(E) INSULATION COORDINATION FOR
29、 EQUIPMENT WITHIN LOW-VOLTAGE SYSTEMS Part 2-2: Interface considerations Application guide 1 Scope This technical report provides an overview of the different kinds of surge overvoltages that can occur on low-voltage installations and equipment. In particular: the magnitude and duration of typical s
30、urges as well as their frequency of occurrence; information on overvoltages resulting from interaction between power and communication systems; guidelines when considering interface issues in relation to insulation coordination; guidelines concerning surge protection means on the basis of availabili
31、ty and risk considerations, including interaction within the system; highlights temporary overvoltages and other factors that have to be taken into account for insulation coordination, primarily related to protective control using surge protective devices. 2 Reference documents IEC 60364-4-44, Elect
32、rical installations of buildings Part 4-44: Protection for safety Protection against voltage disturbances and electromagnetic disturbances IEC 60664-1, Insulation coordination for equipment within low-voltage systems Part 1: Principles, requirements and tests IEC 61000-4-5, Electromagnetic compatibi
33、lity (EMC) Part 4-5: Testing and measurement techniques Surge immunity test IEC TS 61312-3, Protection against lightning electromagnetic impulse Part 3: Requirements of surge protective devices (SPDs) IEC 61643-1, Surge protective devices connected to low-voltage power distribution systems Part 1: P
34、erformance requirements and testing methods IEC TR 62066, General basic information regarding surge overvoltages and surge protection in low-voltage a.c. power systems 1 IEC 61643-12, Surge protective devices connected to low-voltage power distribution systems Part 12: Selection and application prin
35、ciples 1 1To be published.TR 60664-2-2 IEC:2002(E) 7 3 Definitions For the purpose of this technical report, the following definitions apply. 3.1 overvoltage category numeral defining an transient overvoltage condition (IEC 60664-1, 1.3.10) 3.2 controlled overvoltage condition condition within an el
36、ectrical system wherein the expected transient overvoltages are limited to a defined level (1.3.16 of IEC 60664-1) 3.3 inherent control transient overvoltages limited by the electrical distribution system 3.4 protective control transient overvoltages limited by devices such as surge protective devic
37、es (SPDs) 3.5 rated impulse voltage impulse withstand voltage value assigned by the manufacturer to the equipment or a part of it, characterizing the specified withstand capability of its insulation against transient overvoltages (IEC 60664-1,1.3.9.2) 4 Consideration of overvoltage categories Insula
38、tion coordination for equipment relies on a series of steps. The first step is to determine the overvoltage category for the equipment (see IEC 60664-1, 2.2.2.1.1). An overvoltage category is an indication of the degree of risk acceptable for the particular application. The overvoltage category can
39、be determined by either knowledge of the inherent control or by use of protective control. Protective control using SPDs could introduce an aspect of risk if the SPD fails or becomes ineffective. There are methods to indicate failure of an SPD and methods to automatically disconnect equipment from t
40、he supply system if it should fail. This latter method may be an appropriate in certain applications (see IEC 61643-1 and IEC 61643-12). Determination of the overvoltage category leads to the selection of the rated impulse voltage using the tables in IEC 60664-1. 5 Consideration on the use of protec
41、tive control 5.1 General The installer will decide whether to provide protective control in an installation on the basis of local information (good practice), regulation etc. 8 TR 60664-2-2 IEC:2002(E) Protective control of the equipment may be a decision taken either by the manufacturer or the user
42、. There are two significant elements in this decision-making process: the evaluation of the need for protective control, depending on the type of installation, the type and purpose of equipment and an assessment of the risks; the evaluation of the level of protective control against overvoltages for
43、 an indirect lightning strike. Overvoltages can be induced into the circuits of the installation or result from currents injected into medium-voltage or low-voltage systems by an indirect lightning strike at some distance from the installation. A similar evaluation is applicable to switching overvol
44、tages. More information is known about induced lightning overvoltages on low-voltage overhead lines than for inside building installations. Even less is known about overvoltages on equipment, including switching overvoltages. The estimated probability of overvoltages (number/year/km) represent the “
45、prospective overvoltages“ (not influenced by any reaction of the system, such as a flashover). In practical cases, distortion and limitations are present due to multiple branches, cable sections, loads, flashovers, overvoltage protection devices, etc. The statistical distribution should therefore be
46、 expected to be somewhat modified in real cases. In particular, the frequency of overvoltages with magnitudes exceeding the normal line insulation level will be reduced. From the reference data on the occurrence of overvoltages, more surge-related failures of equipment than what is actually being ob
47、served may be expected. This discrepancy can be explained by several factors: actual probability of the event at a given location; mitigating effect of multiple paths offered to the surges; actual behaviour of transmission lines; loading effect by linear as well as non-linear loads; presence of SPDs
48、; unrecognized flashover due to very high overvoltages, etc. One model used for analysis demonstrated that for a typical low-voltage line (230/400 V, twisted cable, three-phase and neutral), and for a flash density of 2,2 flashes per year per kilometre, the prospective number of overvoltages exceedi
49、ng the insulation level of 4 kV for a 230 V TN system, such as 4 kV for a 230 V TN system, is in the order of one occurrence every other year. However, even such a low frequency of overvoltage occurrence may not be acceptable if it results in failure within an installation or of critical equipment. Therefore, the degree of acceptable risk must be taken into consideration for each situation. Overvoltages between conductors and local earth stress the insulati
