1、 IEEE Guide for Loading Mineral-Oil-Immersed Transformers and Step-Voltage Regulators Sponsored by the Transformers Committee IEEE 3 Park Avenue New York, NY 10016-5997 USA 7 March 2012 IEEE Power +1 978 750 8400. Permission to photocopy portions of any individual standard for educational classroom
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15、All rights reserved. vi Copyright 2012 IEEE. All rights reserved. Participants At the time this guide was completed, the C57.91 Working Group had the following membership: Don Duckett, Chair Carlo Arpino, Vice Chair Susan McNelly, Secretary/Technical Editor Javier Arteaga Peter Balma Barry Beaster J
16、uan Castellanos Jonathan Cheatham Luiz Cheim Bill Chiu Craig Colopy Alan Darwin Donald Fallon Joseph Foldi Bruce Forsyth Michael Franchek George Frimpong Eduardo Garcia David Goodwin Shamaun Hakim Jack Hammers Roger Hayes Gary Hoffman Thomas Holifield Virendra Jhonsa Gael Kennedy John Lackey Michael
17、 Lau Richard Marek Terence Martin Phillip McClure Vinay Mehrotra Amitav Mukerji Paul Mushill Van Nhi Nguyen T. V. Oommen David Ostrander Mark Perkins Tony Pink Donald Platts Thomas Prevost Timothy Raymond Kirk Robbins Oleg Roizman Surinder Sandhu Brett Sargent H. Jin Sim Giuseppe Termini Jim Thompso
18、n Robert Thompson Robert Tillman Roger Verdolin David Wallach Roger Wicks Jim Zhang Hanxin Zhu Abderrahmane Zouaghi The following members of the individual balloting committee voted on this guide. Balloters may have voted for approval, disapproval, or abstention William J. Ackerman Samuel Aguirre St
19、ephen Antosz James Armstrong Carlo Arpino Peter Balma Barry Beaster W. J. Bil Bergman Steven Bezner Wallace Binder Thomas Bishop Thomas Blackburn Daniel Blaydon William Bloethe W. Boettger Chris Brooks Carl Bush Juan Castellanos Arvind K. Chaudhary Donald Cherry C. Clair Claiborne Kurt Clemente Mich
20、ael Coddington Jerry Corkran John Crouse Alan Darwin Dieter Dohnal Gary Donner Randall Dotson Don Duckett Fred Elliott Gary Engmann James Fairris Michael Faulkenberry Joseph Foldi Bruce Forsyth Marcel Fortin David Gilmer Jalal Gohari James Graham Randall Groves Bal Gupta J. Harlow David Harris Roger
21、 Hayes Gary Heuston Gary Hoffman Thomas Holifield Philip Hopkinson R. Jackson Laszlo Kadar Gael Kennedy Morteza Khodaie Joseph L. Koepfinger Neil Kranich David Krause Jim Kulchisky Saumen Kundu John Lackey Chung-Yiu Lam Stephen Lambert Thomas La Rose Aleksandr Levin Thomas Lundquist Richard Marek J.
22、 Dennis Marlow John W. Matthews Lee Matthews Phillip McClure Charles Morgan Daniel Mulkey Jerry Murphy Ryan Musgrove K. R. M. Nair Michael S. Newman Joe Nims Ed Te Nyenhuis Robert Olen Mohamed Omran Bansi Patel J. Patton Brian Penny Howard Penrose Mark Perkins Patrick Picher Donald Platts Alvaro Por
23、tillo Bertrand Poulin Gustav Preininger Jean-Christophe Riboud Michael Roberts Charles Rogers Oleg Roizman John Rossetti Thomas Rozek Bob Saint Dinesh Sankarakurup Bartien Sayogo Devki Sharma Stephen Shull Gil Shultz James Smith Jeremy Smith Jerry Smith Steve Snyder Brian Sparling Ronald Stahara Dav
24、id Stankes Gary Stoedter Malcolm Thaden James Thompson Alan Traut Joseph Tumidajski John Vergis Jane Verner David Wallach John Wang Barry Ward Roger Wicks Alan Wilks John Wilson William Wimmer Waldemar Ziomek When the IEEE-SA Standards Board approved this standard on 7 December 2011, it had the foll
25、owing membership: Richard H. Hulett, Chair John Kulick, Vice Chair Robert M. Grow, Past Chair Judith Gorman, Secretary Masayuki Ariyoshi William Bartley Ted Burse Clint Chaplin Wael Diab Jean-Philippe Faure Alex Gelman Paul Houz Jim Hughes Joseph L. Koepfinger* David Law Thomas Lee Hung Ling Oleg Lo
26、gvinov Ted Olsen Gary Robinson Jon Rosdahl Sam Sciacca Mike Seavey Curtis Siller Phil Winston Howard Wolfman Don Wright * Member Emeritus Also included are the following nonvoting IEEE-SA Standards Board liaisons: Satish Aggarwal, NRC Representative Richard DeBlasio, DOE Representative Michael Janez
27、ic, NIST Representative Catherine Berger IEEE Standards Project Editor Erin Spiewak IEEE Standards Program Manager, Technical Program Development vii Copyright 2012 IEEE. All rights reserved. viii Copyright 2012 IEEE. All rights reserved. Introduction This introduction is not part of IEEE Std C57.91
28、-2011, IEEE Guide for Loading Mineral-Oil-Immersed Transformers and Step-Voltage Regulators. This guide is applicable to loading 65 C mineral-oil-immersed distribution and power transformers. Guides for loading, IEEE Std C57.91-1981 (prior edition), IEEE Std C57.92-1981,aand IEEE Std C57.115-1991 (r
29、edesignated as IEEE Std 756) are all combined in this document as the basic theory of transformer loading is the same, whether the subject is distribution transformers, power transformers 100 MVA and smaller, or transformers larger than 100 MVA. In recognition of different types of construction, spe
30、cial considerations, and the degree of conservatism involved in the loading of this equipment, specific sections are devoted to power transformers and distribution transformers. In the previously referenced information, the guide for units larger than 100 MVA referenced the IEEE Std C57.92-1981 load
31、ing guide for units up to and including 100 MVA. This update to the work done in 1995 expands the scope to include step-voltage regulators and replaces Annex A with an improved discussion on bubble evolution. Subclause 8.4 was added for step-voltage regulators. In addition, the formula notations wer
32、e changed to reflect the updated IEEE style and a number of typographical errors were fixed. Both Clause 7 and Annex G calculation procedures remain in place. Clause J was removed as out-of-date information and is expected to be re-introduced in the future in a new standard on transformer monitoring
33、 systems. Annex C and Annex G were changed from normative to informative. As IEEE Std C57.12.00-2010bhas adopted an insulation life of 180 000 hours at 110 C, Table 2 of this guide has been moved to Annex I for historical reference. In previous guides, different insulation aging curves were used for
34、 power transformers and distribution transformers. This was caused by the different evaluation procedures used. The distribution transformer curve was based on aging tests of actual transformers. The power transformer curve was based on aging insulation samples in test containers to achieve 50% rete
35、ntion of tensile strength. Investigation of cellulosic insulating materials removed from transformers that had long service life has led knowledgeable people to question the validity of the 50% criteria. One newer criteria suggested is 25% retention. This guide will permit the user to select the cri
36、teria most acceptable to their need, based on percent strength retention, polymerization index, etc. An insulation aging factor may thus be applied. A per unit life concept and aging acceleration factor are provided in this loading guide. The equations given may be used to calculate percent loss of
37、total insulation life, as has been the practice in earlier editions of the transformer loading guides. The relationship between insulation life and transformer life is a question that remains to be resolved. It is recognized that under the proper conditions, transformer life can well exceed the life
38、 of the insulation. The assumed characteristics used in previous guides contained tables of loading capability based on assumed typical transformer characteristics. These assumed characteristics were recognized as not being those of actually built units, which may have a wide range of characteristic
39、s. In this guide these tables were removed since computer technology permits calculation of loading capability based on specific transformer characteristics. Two methods of calculating temperatures are given in this guide. Clause 7 contains temperature equations similar to those used in previous edi
40、tions of this guide. These equations use the winding hot spot rise over tank top oil and assume that the oil temperature in the cooling ducts is the same as the tank top oil during overloads. Recent research using imbedded thermocouples and fiber optic detectors indicates that the fluid aIEEE Std C5
41、7.92-1981 has been withdrawn; however, copies can be obtained from Global Engineering, 15 Inverness Way East, Englewood, CO 80112-5704, USA, tel. (303) 792-2181 (http:/ bInformation of references can be found in Clause 2. ix Copyright 2012 IEEE. All rights reserved. flow occurring in the windings du
42、ring transient heating and cooling is an extremely complicated phenomena to describe by simple equations. These recent investigations have shown that during overloads, the temperature of the oil in the winding cooling ducts rises rapidly and exceeds the top-oil temperature in the tank. An alternate
43、set of equations based on this concept is given in Annex G. The change of losses with temperature and liquid viscosity effects, and variable ambient temperature was incorporated into the equations. A computer program based on these equations is given for evaluation by the industry. Research in this
44、field is ongoing at this time and may be incorporated into future revisions of this guide. Changes in the guide, in addition to the consolidation, include information to more accurately load transformers operating down to a 30 C ambient, this information concerns loss of diversity due to cold load p
45、ick-up or unusually low ambient temperatures. Transformers rated 55 C rise were generally replaced as a standard offering by most manufacturers about 1966. Their replacements were originally rated 55/65 C and in 1977 the single 65 C rated transformers became the industry standard offering. The highe
46、r temperature ratings are based on thermally upgraded oil-paper-enamel insulation systems. Loading of 55 C insulation system transformers is covered in Annex D. Suggestions for improvement gained in the use of this guide will be welcomed. They should be sent to the IEEE Standards Department. Content
47、s 1. Overview 1 1.1 Scope . 1 1.2 Purpose 1 2. Normative references 2 3. Definitions 2 4. Effect of loading beyond nameplate rating. 3 4.1 General 3 4.2 Voltage and frequency considerations. 3 4.3 Supplemental cooling of existing self-cooled transformers. 4 4.4 Information for user calculations. 4 5
48、. Transformer insulation life . 5 5.1 General 5 5.2 Aging equations. 6 5.3 Percent loss of life . 10 6. Ambient temperature and its influence on loading. 11 6.1 General 11 6.2 Approximating ambient temperature for air-cooled transformers . 11 6.3 Approximating ambient temperature for water-cooled tr
49、ansformers. 11 6.4 Influence of ambient on loading for normal life expectancy . 11 7. Calculation of temperatures 12 7.1 Load cycles 12 7.2 Calculation of temperatures. 14 7.3 Computer calculation of loading capability. 21 7.4 Bibliography for Clause 7 22 8. Loading of distribution transformers and step-voltage regulators 24 8.1 Life expectancy 24 8.2 Limitations. 24 8.3 Types of loading 25 8.4 Loading specific to voltage regulators. 28 9. Loading of power transformers 29 9.1 Types of loading and their interrelationship 29 9.2 Limitations. 30 9.3 N
