1、 IEC 60076-12Edition 1.0 2008-11INTERNATIONAL STANDARD NORME INTERNATIONALEPower transformers Part 12: Loading guide for dry-type power transformers Transformateurs de puissance Partie 12: Guide de charge pour transformateurs de puissance de type sec IEC60076-12:2008 THIS PUBLICATION IS COPYRIGHT PR
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16、ciec.ch Tl.: +41 22 919 02 11 Fax: +41 22 919 03 00 IEC 60076-12Edition 1.0 2008-11INTERNATIONAL STANDARD NORME INTERNATIONALEPower transformers Part 12: Loading guide for dry-type power transformers Transformateurs de puissance Partie 12: Guide de charge pour transformateurs de puissance de type se
17、c INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE VICS 29.180 PRICE CODECODE PRIXISBN 2-8318-1015-2 Registered trademark of the International Electrotechnical Commission Marque dpose de la Commission Electrotechnique Internationale 2 60076-12 IEC:2008 CONTENTS FO
18、REWORD.4 INTRODUCTION.6 1 Scope.7 2 Normative references .7 3 Terms and definitions .7 4 Effect of loading beyond nameplate rating 8 4.1 General .8 4.2 General consequences8 4.3 Effects and hazards of short-time emergency loading8 4.4 Effects of long-time emergency loading .9 5 Ageing and transforme
19、r insulation lifetime 9 5.1 General .9 5.2 Lifetime .9 5.3 Relation between constant continuous load and temperature 10 5.4 Ageing rate11 5.5 Lifetime consumption 11 5.6 Hot-spot temperature in steady state.11 5.7 Assumed hot-spot factor12 5.8 Hot-spot temperature rises at varying ambient temperatur
20、e and load conditions12 5.9 Loading equations .12 5.9.1 Continuous loading12 5.9.2 Transient loading.13 5.10 Determination of winding time constant .14 5.10.1 General .14 5.10.2 Time constant calculation method14 5.10.3 Time constant test method.15 5.11 Determination of winding time constant accordi
21、ng to empirical constant 15 5.12 Calculation of loading capability 15 6 Limitations17 6.1 Current and temperature limitations.17 6.2 Other limitations 17 6.2.1 Magnetic leakage field in structural metallic parts17 6.2.2 Accessories and other considerations17 6.2.3 Transformers in an enclosure 18 6.2
22、.4 Outdoor ambient conditions .18 Annex A (informative) Ageing rate .19 Annex B (informative) Examples of lifetime consumptions for 3 load regimes.24 Annex C (informative) List of symbols 33 Bibliography35 Figure A.1 Molecule structure of an epoxy .19 Figure A.2 Thermal endurance graph .22 Figure B.
23、1 Step change loading curve25 Figure B.2 Hot-spot temperature rise and life consumption 27 60076-12 IEC:2008 3 Figure B.3 Load current and winding hot-spot temperature rise30 Figure B.4 Ageing rate versus time 30 Table 1 Constants for lifetime equation 10 Table 2 Maximum hot-spot winding temperature
24、 16 Table 3 Current and temperature limits applicable to loading beyond nameplate rating.17 Table B.1 Lifetime consumption calculations26 Table B.2 Life consumption calculations for varying load .29 Table B.3 Life consumption calculation 31 4 60076-12 IEC:2008 INTERNATIONAL ELECTROTECHNICAL COMMISSI
25、ON _ POWER TRANSFORMERS Part 12: Loading guide for dry-type power transformers FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promot
26、e 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 Specifications (PAS) and Guides (h
27、ereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also p
28、articipate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible
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32、e its approval and cannot be rendered responsible for any equipment declared to be in conformity with an IEC Publication. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including in
33、dividual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upo
34、n, 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 possibility that some of the elements
35、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. International Standard IEC 60076-12 has been prepared by IEC technical committee 14: Power transformers. This standards cancels and replaces IEC 60905 (1987).
36、 This first edition constitutes a technical revision. The text of this standard is based on the following documents: FDIS Report on voting 14/584/FDIS 14/590/RVD Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This p
37、ublication has been drafted in accordance with the ISO/IEC Directives, Part 2. 60076-12 IEC:2008 5 A list of all parts of IEC 60076 series, under the general title Power transformers, can be found on the IEC website. The committee has decided that the contents of this publication will remain unchang
38、ed 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 reconfirmed; withdrawn: replaced by a revised edition; or amended. 6 60076-12 IEC:2008 INTRODUCTION This part of IEC
39、 60076 provides guidance for the specification and loading of dry type power transformers from the point of view of operating temperatures and thermal ageing. It provides the consequence of loading above the nameplate rating and guidance for the planner to choose appropriate rated quantities and loa
40、ding conditions for new installations. IEC 60076-11 is the basis for contractual agreements and it contains the requirements and tests relating to temperature-rise figures for dry type power transformers during continuous rated loading. It should be noted that IEC 60076-11 refers to the average wind
41、ing temperature rise while this part of IEC 60076 refers mainly to the hot-spot temperature and the latter stated values are provided only for guidance. This part of IEC 60076 gives mathematical models for judging the consequence of different loading, with different temperatures of the cooling mediu
42、m, and with transient or cyclical variation with time. The models provide for the calculation of operating temperatures in the transformer, particularly the temperature of the hottest part of the winding. This hot-spot temperature is used for estimation of the number of hours of life time consumed d
43、uring a particular time period. This part of IEC 60076 further presents recommendations for limitations of permissible loading according to the results of temperature calculations or measurements. These recommendations refer to different types of loading duty continuous loading, short-time and long
44、time emergency loading. An explanation of ageing fundamentals is given in Annex A. 60076-12 IEC:2008 7 POWER TRANSFORMERS Part 12: Loading guide for dry-type power transformers 1 Scope This part of IEC 60076 is applicable to dry-type transformers according to the scope of IEC 60076-11. It provides t
45、he means to estimate ageing rate and consumption of lifetime of the transformer insulation as a function of the operating temperature, time and the loading of the transformer. NOTE For special applications such as wind turbine application transformers, furnace transformers, welding machine transform
46、ers, and others, the manufacturer should be consulted regarding the particular loading profile. 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 e
47、dition of the referenced document (including any amendments) applies. IEC 60076-11, Power transformers Part 11: Dry-type transformers IEC 60216-1, Electrical insulating materials Properties of thermal endurance Part 1: Ageing procedures and evaluation of test results IEC 61378-1:1997, Convertor tran
48、sformers Part 1: Transformers for industrial applications 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 long-time emergency loading loading resulting from the prolonged outage of some system elements that will not be reconnected before the
49、transformer reaches a new and higher steady state temperature 3.2 short-time emergency loading unusually heavy loading of a transient nature (less than one time constant of the coil) due to the occurrence of one or more unlikely events which seriously disturb normal system loading 3.3 hot-spot if not specifically defined, “hot-spot” means the hottest-spot of the winding 3.4 relative thermal ageing rat
