IEEE 76-1974 - IEEE Guide for Acceptance and Maintenance of Transformer Askarel in Equipment.pdf

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1、o NOT nEMOVEIEEE Std 76-1974Revision of IEEE Std 761958IEE E Guide forAcceptance and Maintenance ofTransformer Askarel in EquipmentPublished by The Institute of Electrical and Electronics Engineers, Inc. 345 East 47th Street, New York, New York 10017March 1, 1974 SH10769IEEE Std 76-1974 Revision of

2、IEEE Std 76-1958 IEEE Guide for Acceptance and Maintenance of Transformer Askarel in Equipment Sponsor Transformers Committee of the IEEE Power Engineering Society Copyright 1974 by The Institute of Electrical and Electronics Engineers,. Inc. No part of this publication may be reproduced in any form

3、, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. Approved May 24, 1973 IEEE Standards Board Robert D. Briskman, Chairman Sava I. Sherr, Secretary Stephen J. Angello Saul Aronow James E. Beehler Richard Brereton Warren H. Cook Louis Costrell Jay

4、 Forster Joseph L. Koepfinper William R. Kruesi Benjamin J. Leon Donald T. Michael Voss A. Moore J. David M. Phelps Saul W. Rosenthal Gustave Shapiro Ralph M. Showers Robert A. Soderman Frederick G. Timmel Leendert van Rooi.i Robert V. Wachter Bruno O. Weinschel William T. Wintringham Foreword (This

5、 foreword is not a part of IEEE Std 76-1974, IEEE Guide for Acceptance and Maintenance of Transformer Askarel in Equipment.) Originally published in 1958 as a trial-use guide for maintenance of transformer askarel, this stan dards document has been revised, updated, and approved as a full-status IEE

6、E Guide. The new edi tion not only reflects current practice, it also takes into consideration recent environmental con cerns about materials containing polychlorinated biphenyls. The standard was developed and ap proved by the Insulating Fluids Subcommittee of the IEEE Transformers Committee. At th

7、e time it approved this document, its membership was: P. G. Benignus G. L. Blenkle J. E. Dind J. A. Forster D. A. Gillies C. Keil A. H. Locke R. I. Lowe E. L. Raab, Chairman W. H. Meadet E. L. Morrison V. R. Mulhall J. C. Parkert P. S. Pugh W. C. Reinhardt R. L. Schwab T. K. Sloat t Deceased Followi

8、ng development and approval in the Insulating Fluids Subcommittee, this standard was reviewed and approved in the IEEE Transformers Committee. Membership in that committee was: G. W. Alexander, Vice Chairman J. H. Blake, Chairman L. C. Aicher R. Allustiarti R. J. Alton S. J. Antalis J. C. Arnold R.

9、R. Bast P. L. Bellaschi S. Bennon H. E. Bonheimer J. V. Bonucchi O. R. Compton J. E. Dind J. D. Douglass J. C. Dutton L. L. Dvorak H. P. Edler W. R. Farber S. L. Foster A. M. Fox E. R. Freitag C. R. French L. A. Gates R. F. Gilton A. Glassano8 A. W. Goldman J. C. Gorub R. W. Green W. F. Griffard E.

10、M. Gulachenski G. Gunnels G. H. Hall J. L. Harbell W. L. Hetherington K. R. Highton J. A. Hollowell E. L Hook G. W. Iliff W. D. Jordan G. K. Kallenbach C. P. Kappeler R. B. Kaufman C. Keil F.J.Kelly L. A. Kenoyer T. S. Lauber C. Lindsay A. H. Locke A. M. Lockie L. W. Long R. L. Macdonald H. B. Margo

11、lis D. E. Massey C. J. McMUlen C. H. Mock W. H. Mutschler P. Q. Nelson R. A. Nelson M. A. Oman S. Palmer A. F. Phillips L. L. Preston E. L. Raab D. A. Roach C. C. Honey, Secretary R. E. Russell L. J. Savio R. L. Schmid R. L. Schwab L. R. Smith A. L. Tanton R. C. Thomas D. E. Truax R. A. Veitch F.J.V

12、ogel J. P. Vora E. H. Wendt S. A. Wiencek G. C. Wilburn D. F. Winter J. R. Woodall W. E. Wrenn A. C. Wurdack F. S. Young L. R. Yule Contents SECTION PAGE 1. Scope and Introduction 5 2. General Characteristics of Askarel3. Evaluation of Askarel Received in New Equipment 6 4. Classification of Service

13、-Aged Askarel 6 5. Economic Factors 7 6. Sampling7. Askarel Tests and Their Significance 8 8. Testing Procedures 10 8.1 Field Screening8.2 Laboratory Screening9. Reconditioning and Reclaiming Service-Aged Askarel 10 9.1 General9.2 Treatment After Exposure to an Arc 19.3 Filtering Through Dry Blotter

14、 Paper to Remove Moisture and Extraneous Particles 1 9.4 Fullers Earth Treatment for Maximum Improvement of Power Factor and Volume Resistivity 19.5 Addition of Scavengers 110. Handling Materials11. Askarel Used Under Mild Arcing Conditions 12 12. Askarel Under Excessive Temperature or Fault Conditi

15、ons 113. Recommended Handling Precautions14. Storage, Handling, and Disposal 13 14.1 Drums 114.2 Tank Cars14.3 Sampling14.4 Effect of Light Exposure 13 14.5 Disposal15. Underwriters Laboratories ReportsAppendix: Results of Survey of United States and Canadian Users of Transformer Askarel 15 Al. Gene

16、ral 1A2. TestingA3. Reconditioning 6 A4. Frequence of Testing 1TABLES Table 1 Table 2 Acceptable Characteristics of Askarel in New Equipment Askarel Tests to Determine Classification 7 9 IEEE Guide for Acceptance and Maintenance of Transformer Askarel in Equipment 1. Scope and Introduction The term

17、askarel generally describes a wide ly used broad class of nonflammable synthetic halogenated hydrocarbon insulating liquids. In this guide, it applies solely to askarel in transformers, reactors, and accessory equip ment operated at power frequencies. Transformer askarels contain PCBs (poly-chlorina

18、ted biphenyls), which have been used in the United States and elsewhere over the past 40 years for many industrial and consum er applications. Recently, evidence has accu mulated to indicate that PCBs are widely dis persed throughout the environment and that they can have adverse ecological and tox-

19、icological effects. The Federal Interdepartmental Task Force report COM-72-10419, Poly chlorinated Bi phenyls and the Environment/* dated May 1972, has recommended restricting PCBs to use in transformers and capacitors. Methods for handling and disposal of ask arels and askarel-impregnated materials

20、 are given in Draft American National Standard, Guidelines for Handling and Disposal of Capacitor and Transformer-Grade Askar els Containing Polychlorinated Biphenyls, C107.1. This guide assists the power equipment op erator in evaluating askarel as received in transformers, reactors, and accessory

21、equip ment operated at power frequencies and in his efforts to maintain askarel in serviceable con dition. It recommends standardized tests and evaluation procedures. Methods are outlined for reconditioning and reclaiming askarel whenever necessary. 2. General Characteristics of Askarel Askarels of

22、various compositional types are used. Under arcing conditions the gases pro duced, while consisting of predominantly noncombustible hydrogen chloride, can yield varying amounts of combustible gases depend ing upon the askarel type. Insulation systems incorporating these ask arels and cellulosic or o

23、ther organic materials may, when arced, produce gaseous mixtures which are moderately flammable. As a pre caution, such gases should be removed from the askarel by bubbling dry nitrogen through the askarel and flushing the gas space with dry nitrogen before any work is performed on the apparatus. As

24、karel contained in apparatus as received from the manufacturer but prior to service op eration should exhibit certain properties in or der to insure satisfactory performance. It should be expected that askarel properly sam pled from such equipment usually exhibits characteristics somewhat different

25、from those obtained on new askarel which has not been in contact with apparatus constructional ma terials. Experience has indicated that vari ation of some characteristics of the askarel will not impair the service life of the equip ment. However, certain essential properties must be retained if ask

26、arel is to perform reliably its dual role of electrical insulation and heat transfer agent. It must have adequate dryness and a dielectric strength sufficient to with stand the electric stresses imposed in service. It must retain a sufficiently low viscosity so that its ability to circulate and tran

27、sfer heat is not impaired. It should not be allowed to be come so deteriorated or contaminated that it adversely affects the operation of the ap paratus. In comparison to mineral insulating oil, askarel is a relatively polar material; that is, its molecules are dipoles, free to rotate around their a

28、xes and responsive to orientation by electrical forces. Askarel also exhibits a much higher dielectric constant and capacitance than insulating oil, and these differences must 5 IEEE Std 76-1974 IEEE GUIDE FOR ACCEPTANCE AND MAINTENANCE OF be kept in mind when interpreting electrical test data. Beca

29、use it is relatively polar and possesses high solvency power, askarel is much more electrically sensitive to trace contaminants than insulating oil, and consequently the choice of constructional materials destined for use in askarel is very critical. This sensitivity is reflected in the power factor

30、 and resistivity (specific resistance) of the askarel. It is important to note that, with the ex ception of water, the dielectric breakdown voltage of askarel is not generally adversely af fected by many of the contaminants to which its power factor and resistivity (specific resist ance) are so sens

31、itive. In fact, the dielectric breakdown voltage of askarel is somewhat greater than that of insulating oil. Therefore, the values assigned these dielectric fluids in newly supplied transformers are 30 kV min imum and 26 kV minimum, respectively. As with insulating oil, askarel must be kept dry. It

32、can pick up moisture from exposure to humid atmosphere. Under similar conditions of exposure, askarel can pick up nearly twice as much moisture when measured on a parts per million weight basis. A final obvious difference is that askarel is about one and one half times as heavy as wa ter, whereas mi

33、neral oil is lighter than water. This means that any free water present will float on askarel, whereas free water in oil will be at the bottom. 3. Evaluation of Askarel Received in New Equipment Some users of askarel equipment find it de sirable to make “as received tests“ on all equipment. It is qu

34、ite common to use the di electric breakdown voltage test and visual ap pearance as the most significant tests. If suit able equipment and trained personnel are available, additional information may be ob tained from the power factor, color, and mois ture content tests. In sampling askarel contained

35、in ap paratus, extreme care must be exercised in or der to obtain a representative sample. ASTM Standard D 923-70 (ANSI C59.21-1973), Sam pling Electrical Insulating Liquids,l should be followed. New equipment with askarel exhibiting the characteristics given in Table 1 is considered acceptable. The

36、 significance of the foregoing and other tests listed in this guide are discussed in Sec tion 7. 4. Classification of Service-Aged Askarel It is extremely difficult, if not impossible, to indicate the value of specific tests and recom mended test limits for all possible existing ap plications of ask

37、arel. It should also be recog nized that with the present state of knowledge no one test can be used as the sole criterion of condition of askarel. It is possible, however, to summarize the value and importance of cur rent tests and to suggest methods of treatment for the askarel being examined, suc

38、h methods being based on current industry experience. Askarel may be placed in the following classi fications based upon composite evaluation of significant characteristics and on field and laboratory screening tests. Group L This group contains askarel which is in satisfactory condition for continu

39、ed use. Group II. This group contains askarel which requires only minor reconditioning for further service. (Reconditioning is the remov al of moisture and insoluble contaminants. The usual method employed is filtration.) Group HI. This group contains askarel in poor condition. It should be reclaime

40、d or dis carded depending upon economic consid erations. (Reclamation involves the use of methods and processes which result in a puri fication of the askarel. Treatment with an ab sorbing agent such as fullers earth is most widely used.) Group IV. This group contains askarel in such poor condition

41、and requiring such dras-lASTM Standards referred to in this guide are ob tainable from Headquarters, American Society for Test ing and Materials, 1916 Race Street, Philadelphia, Pa, and from the American National Standards Institute, 1430 Broadway, New York, NY 10018. 6 TRANSFORMER ASKAREL IN EQUIPM

42、ENT IEEE Std 76-1974 Table 1 Acceptable Characteristics of Askarel in New Equipment Characteristics ASTM Standards Dielectric breakdown voltage 30 kV minimum D 877-67 (1971) (ANSI C59.19-1968) (R1973) Color 300 maximum (straw color) D 2129-64 (1969) (ANSI C59.114-1970) Visual condition clear D1702-6

43、6 (1971) (ANSI C59.104-1970) Water content 35 parts per million max D 1533-61 (1969) (ANSI C59.53-1963 (R1969) Power factor at 25C * D 924-65 (1969) (ANSI C59.22-1967) (R1973) D 150-70 The power factor of askarel taken from new transformers, reactors, and accessory equipment can reflect the presence

44、 of moisture, dissolved polar compounds, or other contaminants and may vary with the type of equipment from which the sample was taken due to the different ratios of liquid-to-solid insulation and to the high solvency power of the askarel. Given an acceptable water content and dielectric breakdown v

45、oltage of the askarel as indicated above, a high power factor seldom impairs the serviceability of the askarel within rather broad limits and is indica tive of the degree of contamination present. Recognizing the possibility of a wide range of power factors being recorded for askarel in new equipmen

46、t, it is difficult to establish a single limit which would be acceptable to both suppliers and users for all applications. How ever, as a broad guide, power factors up to about 10 percent at 25C and 60 Hz do not in general indicate any ab normal contamination providing that the other criteria (water

47、 content, dielectric breakdown voltage, etc) are met. Much higher power factors may indicate excessive contamination or the misapplication of the solid materials used in manufacture in contact with the askarel and should be investigated. tic treatment that it is not feasible either tech nically or e

48、conomically to attempt reclama tion. Examples of such a condition would be a severely arced or excessively oil contaminated askarel. 5. Economic Factors In this section of the guide, askarel is classi fied on the basis of significant characteristics. Many of the undesirable characteristics of used a

49、skarel can be corrected by recon ditioning or reclaiming, if economic condi tions justify it. The alternate choice is to re place with new askarel. A review of the experiences of many users of electric equipment reveals a wide variation in the actual cost data involved in the re conditioning or reclaiming of askarel. This variation can be attributed to the amount and condition of askarel involved, laboratory and shop facilities, whether the work is performed at one central or several distant locations, and the availability of qualified personnel. Askarel that contains water and