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1、IEEE Std C57.144-2004 IEEE Standards C57.144 TM IEEE Guide for Metric Conversion of Transformer Standards 3 Park Avenue, New York, NY 10016-5997, USA IEEE Power Engineering Society Sponsored by the Transformers Committee IEEE Standards 22 October 2004 Print: SH95259 PDF: SS95259 Copyright The Instit
2、ute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEELicensee=IHS Employees/1111111001, User=OConnor, Maurice Not for Resale, 04/28/2007 23:59:09 MDTNo reproduction or networking permitted without license from IHS -,-,- Recognized as an American National Standard
3、(ANSI) The Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue, New York, NY 10016-5997, USA Copyright 2004 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 22 October 2004. Printed in the United States of America. IEEE is a registered t
4、rademark in the U.S. Patent +1 978 750 8400. Permission to photocopy portions of any individual standard for educational classroom use can also be obtained through the Copyright Clearance Center. NOTEAttention is called to the possibility that implementation of this standard may require use of subje
5、ct matter covered by patent rights. By publication of this standard, no position is taken with respect to the exist- ence or validity of any patent rights in connection therewith. The IEEE shall not be responsible for identifying patents for which a license may be required by an IEEE standard or for
6、 conducting inquiries into the legal valid- ity or scope of those patents that are brought to its attention. Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEELicensee=IHS Employees/1111111001, User=OConnor, Maurice Not for Resale, 04/28/200
7、7 23:59:09 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright 2004 IEEE. All rights reserved.iii Introduction (This introduction is not part of IEEE Std C57.144-2004, IEEE Guide for Metric Conversion of Transformer Standards.) In 1995, IEEE implemented a new metric p
8、olicy (IEEE Policy 9.20), which directed that all IEEE publica- tions undergo a transition from U.S. Customary (or inch-pound) units of measure to metric or Le Systme International dUnits (SI). The metric or SI system is the standard for science and engineering and in com- mon usage in nearly all co
9、untries of the world except for the United States. The IEEE Policy directed that standards published after January 2000 were to be expressed solely in metric units. Subsequently, the IEEE-SA Standards Board modified the policy on 11 September 2003 to allow some latitude in conversion from U.S. Custo
10、mary to metric units. The revised policy is identified as Policy 9.19. The new policy states that standards should use metric units exclusively in the normative portions of the standard, but the use of metric units with parenthetical inch-pound units are also permitted. Working groups and subcommitt
11、ees of the IEEE Transformers Committee tried to make these conversions, but when the work of one body was compared with another, it was found that conversions were often made either inconsistently or incorrectly. The existing guide, IEEE/ASTM SI 10TM-2002 and its predecessor, IEEE Std 268TM-1992, we
12、re not being used as intended. Both documents are listed here because some important information regarding conversion of toleranced values has been omitted from the more recent guide. The Transformers Committee formed a Metric Conversion Task Force to address the problems encountered by the working
13、groups in revising their standards. The Task Force presented tutorials for Trans- formers Committee members and is hereby creating an IEEE guide to create a better understanding of metric usage and of conversion methods as they apply to Transformer Standards. Notice to users Errata Errata, if any, f
14、or this and all other standards can be accessed at the following URL: http:/ standards.ieee.org/reading/ieee/updates/errata/index.html. Users are encouraged to check this URL for errata periodically. Interpretations Current interpretations can be accessed at the following URL: http:/standards.ieee.o
15、rg/reading/ieee/interp/ index.html. Patents Attention is called to the possibility that implementation of this standard may require use of subject matter covered by patent rights. By publication of this standard, no position is taken with respect to the existence or validity of any patent rights in
16、connection therewith. The IEEE shall not be responsible for identifying patents or patent applications for which a license may be required to implement an IEEE standard or for conducting inquiries into the legal validity or scope of those patents that are brought to its attention. Copyright The Inst
17、itute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEELicensee=IHS Employees/1111111001, User=OConnor, Maurice Not for Resale, 04/28/2007 23:59:09 MDTNo reproduction or networking permitted without license from IHS -,-,- ivCopyright 2004 IEEE. All rights reserved
18、. Participants The following is a list of participants in the Guide to Metric Conversion Working Group. Dudley L. Galloway, Chair Timothy W. Olson, Vice-Chair The following members of the individual balloting committee voted on this guide. Balloters may have voted for approval, disapproval, or abste
19、ntion. Gene Blackburn John Borst Tommy Cooper Michael Culhane Ali Ghafourian Brian Kaplonski Gael R. Kennedy Ron Kirker Michael Mitelman Daniel Mulkey Robert Olen Edwin Owen Thomas Pekarek Stephen Shull Ronald Stahara Donnie Trivitt David Aho Stan J. Arnot Peter M. Balma Ronald Barker W. J. (Bill) B
20、ergman Edward Bertolini Wallace Binder Thomas E. Blackburn III William Boettger Alain Bolliger John Borst Carl Bush Thomas Callsen Max Cambre Tommy Cooper Michael Culhane R. Daubert Guru Dutt Dhingra William Darovny Alan Darwin Byron Davenport Pranathy Dinesh Dieter Dohnal Amir El-Sheikh Fred Elliot
21、t Gary Engmann Mehrdad Eskandary Jorge Fernandez-Daher Joseph Foldi Bruce Forsyth Marcel Fortin Derek Foster Dudley Galloway William Griesacker Randall Groves Erik Guillot Bal Gupta Michael Haas Roger Hayes Ajit Hiranandani Edward Horgan, Jr. James D. Huddleston III Rowland James, Jr. Charles Johnso
22、n Joseph Kelly Gael R.Kennedy Sheldon Kennedy Tanuj Khandelwal Boyd Leuenberger Donald Lowe Gregory Luri Al Maguire William Majeski J. Dennis Marlow John Matthews Lee Matthews Susan McNelly Nigel McQuin Joseph Melanson G. Michael Dan Mulkey Jerry Murphy Richard Musil Krste Najdenkoski Jeffrey Nelson
23、 Joe Nims T. W. Olsen Thomas Pekarek Paul Pillitteri Donald Platts Alvaro Portillo Charles Raymond Johannes Rickmann Peter Risse Oleg Roizman John Rossetti James Ruggieri Surya Santoso Devki Sharma Stephen Shull H. Jin Sim James E. Smith James E. Smith Jerry Smith Thomas Spitzer Allan St. Peter Rona
24、ld Stahara Peter Stewart John Teixeira Malcolm V. Thaden Juan Luis Thierry Thomas Traub Alan Traut John Vandermaar Joe Watson Alan Wilks James Wilson William Wimmer Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEELicensee=IHS Employees/111
25、1111001, User=OConnor, Maurice Not for Resale, 04/28/2007 23:59:09 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright 2004 IEEE. All rights reserved.v When the IEEE-SA Standards Board approved this guide on 24 June 2004, it had the following membership: Don Wright, C
26、hair Steve M. Mills, Vice Chair Judith Gorman, Secretary *Member Emeritus Also included are the following nonvoting IEEE-SA Standards Board liaisons: Satish K. Aggarwal, NRC Representative Richard DeBlasio, DOE Representative Alan Cookson, NIST Representative Savoula Amanatidis IEEE Standards Managi
27、ng Editor Chuck Adams H. Stephen Berger Mark D. Bowman Joseph A. Bruder Bob Davis Roberto de Boisson Julian Forster* Arnold M. Greenspan Mark S. Halpin Raymond Hapeman Richard J. Holleman Richard H. Hulett Lowell G. Johnson Joseph L. Koepfinger* Hermann Koch Thomas J. McGean Daleep C. Mohla Paul Nik
28、olich T. W. Olsen Ronald C. Petersen Gary S. Robinson Frank Stone Malcolm V. Thaden Doug Topping Joe D. Watson Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEELicensee=IHS Employees/1111111001, User=OConnor, Maurice Not for Resale, 04/28/2
29、007 23:59:09 MDTNo reproduction or networking permitted without license from IHS -,-,- viCopyright 2004 IEEE. All rights reserved. Contents 1.Overview 1 1.1 Scope 1 1.2 Purpose. 1 2.References 1 3.Guidelines 2 3.1 Application of converted values 2 3.2 “Hard” and “soft” conversion 2 3.3 Use convenien
30、t numbers 2 3.4 Convert fractions 2 3.5 Determine tolerance. 2 3.6 Maintain original minimums and maximums 2 3.7 Significant digits should be less than 10% of the overall tolerance 3 3.8 Method for conversion of toleranced values 3 3.9 Gauge and absolute pressure 3 3.10 Maintain significant digits.
31、3 3.11 The precision of a value. 4 3.12 Trade sizes . 4 3.13 Standard for rounding 4 3.14 Conversion math 4 3.15 Writing unit symbols . 4 3.16 Capitalization. 4 3.17 Units of force and mass . 4 3.18 Specifying a quantity with a tolerance. 5 3.19 Dual dimensioning. 5 3.20 Temperature conversion 5 3.2
32、1 Default tolerances 5 3.22 Convenience and drawing clarity 5 3.23 Separate + and tolerances . 6 3.24 Safety issues. 6 Annex A (normative) Conversion of quantities common to transformer standards 7 Annex B (normative) Guideline background and development 9 Annex C (informative) Bibliography. 11 Copy
33、right The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEELicensee=IHS Employees/1111111001, User=OConnor, Maurice Not for Resale, 04/28/2007 23:59:09 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright 2004 IEEE. All rig
34、hts reserved.1 IEEE Guide for Metric Conversion of Transformer Standards 1. Overview 1.1 Scope The intent of this guide is to assist the working groups within the IEEE Transformers Committee; thus, specific examples were taken from the transformer-related standards. It should be recognized that iden
35、tification of general principles and procedures could have broader application. 1.2 Purpose The purpose of this guide is to assist Transformer Working Groups in the interpretation of IEEE/ ASTM SI 10TM-20021 and other appropriate standards as they convert their documents to the use of SI units. This
36、 guide is concerned only with the conversion of existing standards, where a manufacturers product that meets the existing standards limits in U.S. Customary units will always meet the new standards limits in SI units. With the exception of a few very specific examples in A.3, there has been no attem
37、pt to make the metric values more rounded or more convenient. Making such changes to a standard may affect the qualification of existing designs and should come only from a consensus of the interested parties in the appropriate working groups. 2. References This guide shall be used in conjunction wi
38、th the following standard. IEEE/ASTM SI 10-2002, American National Standard for Use of the International System of Units (SI): The Modern Metric System.2 1Information on references can be found in Clause 2. 2IEEE publications are available from the Institute of Electrical and Electronics Engineers,
39、Inc., 445 Hoes Lane, Piscataway, NJ 08854, USA (http:/standards.ieee.org/). Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEELicensee=IHS Employees/1111111001, User=OConnor, Maurice Not for Resale, 04/28/2007 23:59:09 MDTNo reproduction or
40、networking permitted without license from IHS -,-,- IEEE Std C57.144-2004IEEE GUIDE FOR METRIC CONVERSION OF TRANSFORMER STANDARDS 2Copyright 2004 IEEE. All rights reserved. 3. Guidelines 3.1 Application of converted values Ensure converted values do not suggest a precision (repeatability or confide
41、nce interval) that you do not need or cannot measure. For example, the precision of a tape measure or other manual measuring method is limited to about 1/32 in (0.031 in) or 1 mm (0.039 in). 3.2 “Hard” and “soft” conversion Although the use of these terms is not recommended, the concepts should be u
42、nderstood: “Soft” conversion is a statement of mathematical identity, without regard to significant digits. For example, a soft conversion of 100 ft = 30.480 m. A “hard” conversion, on the other hand, will be rounded to a more convenient value that is easy to work with, such as 100 ft = 30.5 m. Hard
43、 conversions may maintain a consistent number of significant digits in both values, but the definition does not specifically state this possibility (see Smith B4).3 3.3 Use convenient numbers Overall, 16.5 L/s is handier than 1.65 E-02 m3/s. The liter (or litre) is equal to 0.001 m3 and is recommend
44、ed for common volumes where the use of m3 is unwieldy. For such volumes, use the symbols “L,” “mL,” and “L” only. Do not use units such as “cm3”. 3.4 Convert fractions Dimensions presently in fractional inches should be expressed as decimals to a reasonable level of precision prior to any conversion
45、. Where a prior conversion from fractions is suspected, an exact conversion may have kept excessive decimal places, overstating the precision attainable. For example, a dimension now shown as 0.1875 in probably originated as 3/16 in and should have been expressed as 0.19 in when first decimalized. 3
46、.5 Determine tolerance Before any conversion, try to determine the stated, implied, or inherent tolerance on the quantity. This tolerance may depend on the available measurement methods or on the typical manufacturing technology used. For example, the typical manufacturing tolerance for linear dimen
47、sions for sand-casting with a copper alloy is 1/32 in 0.031 in 0.8 mm. 3.6 Maintain original minimums and maximums Do not violate original minimum and maximum values when converting without considering the consequences. For mating parts that must fit together, expanding a tolerance limit can have se
48、vere consequences. For situations where mating parts are not involved, the expansion of tolerances by small amounts, e.g., fractions of a millimeter, will probably be inconsequential. 3The numbers in brackets correspond to those of the bibliography in Annex C. Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEELicensee=IHS Employees/1111111001, User=OConnor, Maurice Not for Resale, 04/28/2007 23:59:09 MDTNo reproduction or networking permitted without license from IHS -,-,