1、 IEC/TR 61912-2 Edition 1.0 2009-05 TECHNICAL REPORT Low-voltage switchgear and controlgear Over-current protective devices Part 2: Selectivity under over-current conditions IEC/TR 61912-2:2009(E) THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2009 IEC, Geneva, Switzerland All rights reserved. Un
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10、12-2 Edition 1.0 2009-05 TECHNICAL REPORT Low-voltage switchgear and controlgear Over-current protective devices Part 2: Selectivity under over-current conditions INTERNATIONAL ELECTROTECHNICAL COMMISSION V ICS 29.130 PRICE CODE ISBN 2-8318-1042-0 Registered trademark of the International Electrotec
11、hnical Commission 2 TR 61912-2 IEC:2009(E) CONTENTS FOREWORD.4 INTRODUCTION.6 1 Scope.7 2 Normative references .7 3 Terms, definitions and abbreviated terms .8 3.1 Alphabetical index of terms .8 3.2 Terms and definitions 9 3.3 Abbreviated terms .10 4 Scope of selectivity requirements .11 4.1 General
12、 .11 4.2 Motor protection circuit-breaker / Manual motor starter12 5 Selectivity determination 12 5.1 Circuit-breaker as UD12 5.1.1 Selectivity between circuit-breakers.12 5.1.2 Selectivity between a circuit-breaker (UD) and a fuse to IEC 60269-1 (DD) 15 5.1.3 CB/CPS Selectivity between a circuit-br
13、eaker to IEC 60947-2 (UD) and a CPS to IEC 60947-6-2 (DD) .16 5.1.4 Circuit-breaker/MOR Selectivity between a circuit-breaker (UD) and a motor protection overload relay to IEC 60947-4-1 or IEC 60947-4-2 (DD) 17 5.2 Fuse(s) to IEC 60269-1 as UD.18 5.2.1 Fuse/circuit-breaker Selectivity between a fuse
14、 to IEC 60269-1 (UD) and a circuit-breaker (DD) .18 5.2.2 FU/FU Selectivity between fuses to IEC 60269-1 (UD and DD) .20 5.2.3 FU/CPS Selectivity between fuse(s) to IEC 60269-1 (UD) and a CPS to IEC 60947-6-2 (DD)21 5.2.4 FU/MOR Selectivity between fuse(s) to IEC 60269-1 (UD) and a motor overload pr
15、otection relay to IEC 60947-4-1 or IEC 60947-4-2 (DD) 21 6 Residual current devices (RCDs)21 6.1 General .21 6.2 Selectivity RCD/RCD22 6.2.1 Selectivity between RCDs in the case of earth-leakage current22 6.2.2 Selectivity between RCDs in the case of earth-fault (ground-fault) current.23 7 Zone Sele
16、ctive Interlocking (ZSI)24 7.1 General .24 7.2 Operating principle24 7.3 Example25 8 Over-current protection relay (OCR) Single input energizing quantity measuring relays with dependent or independent time.26 Annex A (informative) Examples of selectivity between over-current protection devices Examp
17、les of the grades of selectivity applicable to circuit-breakers 27 Annex B (informative) Standing loads Effect of standing loads on selectivity in the overload zone.30 Bibliography33 TR 61912-2 IEC:2009(E) 3 Figure 1 Comparison of the operating characteristics of circuit-breakers in the overload zon
18、e.13 Figure 2 Example of selectivity in the fault current zone with time-delay short-circuit release .14 Figure 3 Selectivity in the overload zone between a circuit-breaker (UD) and a fuse (DD)16 Figure 4 Circuit-breaker/MOR Circuit-breaker selectivity with motor overload relay.17 Figure 5 ICB/MOR I
19、CB selectivity with motor overload relay .18 Figure 6 Fuse/circuit -breaker - Verification of selectivity between fuse and circuit- breaker for operating time in the overload zone (t 0,1 s for the fuse)19 Figure 7 FU/CB Verification of selectivity between fuse and circuit-breaker for operating time
20、t 0,1 s .19 Figure 8 FU/FU Verification of selectivity between fuses for operating time t 0,1 s .20 Figure 9 RCD characteristics showing selectivity on earth-leakage time-delay Type S versus non-time delay.23 Figure 10 Schematic diagram of an installation designed for multiple supplies with zone sel
21、ective interlocking25 Figure 11 Schematic diagram of mains distribution system with OCR protection 26 Figure A.1 Circuit-breaker coordination example 50 kA/9 kA fault levels .27 Figure A.2 Time-current curves (examples 1 and 2) 28 Figure A.3 Operation in the fault current zone (examples 1 and 2) .28
22、 Figure A.4 Circuit-breaker coordination example 50 kA/20 kA fault levels .29 Figure B.1 Overload and short-circuit zones.30 Figure B.2 OCPDs in series .31 Table 1 Type of selectivity and corresponding subclause number 12 4 TR 61912-2 IEC:2009(E) INTERNATIONAL ELECTROTECHNICAL COMMISSION _ LOW-VOLTA
23、GE SWITCHGEAR AND CONTROLGEAR OVER-CURRENT PROTECTIVE DEVICES Part 2: Selectivity under over-current conditions FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees
24、). The object of 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, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available S
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32、blication, use of, or reliance upon, this IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the poss
33、ibility that some of the elements of this IEC Publication may be the subject of patent rights. 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
34、the publication of a technical report when it has collected data of a different kind from that which is normally published as an International Standard, for example “state of the art“. IEC 61912-2, which is a technical report, has been prepared by subcommittee 17B: Low- voltage switchgear and contro
35、lgear, of IEC technical committee 17: Switchgear and controlgear. The text of this technical report is based on the following documents: Enquiry draft Report on voting 17B/1606/DTR 17B/1666/RVC Full information on the voting for the approval of this technical report can be found in the report on vot
36、ing indicated in the above table. TR 61912-2 IEC:2009(E) 5 This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts of IEC 61912 series, published under the general title Low-voltage switchgear and controlgear Over-current protective devices, can be fo
37、und on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the maintenance result date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication will be reconfirm
38、ed, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. 6 TR 61912-2 IEC:2009(E) INTRODUCTION Low-voltage equipment standards IEC 60947, IEC 60269, IEC 60898-1 and IEC 61009-1 currently include operating characteristics for ove
39、r-current protective devices, defined in terms of the ability of the equipment to operate at levels of over-current up to their maximum short- circuit current ratings. In practice, the installation of such devices in series requires consideration of the relationship between the device characteristic
40、s to achieve the optimum in supply availability in the event of an over-current causing operation of any device. The ability of an over-current device to perform selectively in combination with other such devices needs to be fully understood by the circuit designer to avoid leaving a circuit vulnera
41、ble to unnecessary loss of supply, particularly where critical supplies are concerned. It is also useful to take full advantage of the capability of devices and systems to avoid over-engineering, with the consequent unnecessary additional cost. Selectivity over the whole range of fault current up to
42、 the prospective fault current at the point of installation is not always possible or necessary. A more economic solution may be found in many cases by accepting a limited selectivity, particularly taking into account the low probability of a high short-circuit fault current. Where a short-circuit p
43、rotective device is used to provide back-up protection to a downstream device, guidance on the application is provided in IEC/TR 61912-1. TR 61912-2 IEC:2009(E) 7 LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR OVER-CURRENT PROTECTIVE DEVICES Part 2: Selectivity under over-current conditions 1 Scope This tec
44、hnical report, which serves as an application guide for the determination of selectivity between over-current protective devices of low-voltage switchgear and controlgear, summarises the definitions of the terminology and provides examples of application. The following standards for devices are cons
45、idered in this technical report: IEC 60255-3; IEC 60255-6; IEC 60255-8, IEC 60255-12 IEC 60269-1, IEC 60269-2, IEC 60269-3;IEC 60269-4; IEC 60898-1; IEC 60947 series; IEC 61008-1; IEC 61009-1. This report does not deal with other forms of protection, such as power-reversal protection, directional pr
46、otection and arc-protection systems. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments
47、) applies. IEC 60255 (all parts), Electrical relays IEC 60269-1, Low-voltage fuses Part 1: General requirements IEC 60269-2, Low-voltage fuses Part 2: Supplementary requirements for fuses for use by authorized persons (fuses mainly for industrial application) Examples of standardized systems of fuse
48、s A to I IEC 60269-3, Low-voltage fuses Part 3: Supplementary requirements for fuses for use by unskilled persons (fuses mainly for household and similar applications) IEC 60269-4, Low-voltage fuses Part 4: Supplementary requirements for fuse-links for the protection of semiconductor devices IEC 608
49、98-1, Electrical accessories Circuit-breakers for over-current protection for household and similar installations Part 1: Circuit-breakers for a.c. operation IEC 60947-2, Low-voltage switchgear and controlgear Part 2: Circuit-breakers IEC 60947-4-1, Low-voltage switchgear and controlgear Part 4-1: Contactors and motor- starters Electromechanical contactors and motor-starters
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