Document GK9nE1Yv1zvx4RXqdKJK8neJq

for notification of future revisions of this Standard, fii! out the attached card ^ <+o o o o a: Remove this tab MONS 091644 before mailing IEEE Std 76-1974 Revision of IEEE Std 76-1968 IEEE Guide for Acceptance and Maintenance of Transformer Askarel in Equipment Sponsor Transformers Committee of the IEEE Power Engineering Society C Copyright 1974 by The Institute of Electrical and Electronics Engineers, Inc. No part of thit publication may be reproduced in any form, in an electronic retrieval eyetem or otherwite, without the prior written permietion of the publisher. MONS 091845 Approved May 24, 1973 IEEE Standards Board Robert 1). Briskman. Chairman Sava 1. Sherr, Scrrr (ary Stephen ). Aiuh'IIo Saul Aronow Jhiiii-h F- Decider Richard Drereton Warren H (V>nk Louis ('ostrell ,Jv Forster Joseph L. Koepfinuer William H. Kruesi Benjamin J. Leon Donald T Michael Vobs A. Moore J. David M. Fhelps Saul W. Rosenthal (ustave Shapiro Ralph M. Showers Robert A. Sodernum Frederick G. Tunnicl Leendert van Rooii Robert V. Wachler Bruno O. Wcinsrhcl William T Wintringhum mons 091846 Foreword (This foreword it 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 IEEE 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 the time it approved this document, its membership was: P.G. Benignus G.L. Blenklc J R Dind I). A. Gillies C. Kri) A.H. Locke It. I. Lowe W.H. Meadet E. L. Raab, Chairman E.L. Morrison V.R. Mulhall J.C. Parkert P.S. Pugh W.C. Reinhardt R L. Schwab T-K. Stoat t Deceased Following development and approval in the Insulating Fluids Subcommittee, this standard was reviewed and approved in the IEEE Transformers Committee. Membership in that committee was: J. H. Blake, Chairman G. W. Alexander, Vice Chairman C. C. Honey, Secretary 2,. C. Aichar K. AliUftiart* R. J. Alton S. J. Antalis J. C. Arnold R. R. Bast P. L. Bellaachi S. Bennon H. E. Bonheimer J. V. Bonucchi 0. R Compton J. K I)ind J. D. Douglass J. C. Dutton L. L. Dvorak H. P. Edler W. R. Farber S. L. Fotter A. M. Fon E, R. Freitas C. R. French L. A. Gates R. F Gilton A. Glaaaanoa A. W. Goldman J. C. Corub R. W. Green W. F. Griffard E. M. Gulachenski G. Gunnel* G H. Hail J. L, Harbeil W. L. Hetherington K. R. Highton J. A. Hollowed E. L. Hook G.W. lliff 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- Margolia D. E. Maaaey C. J. McMillen C. H. Mock W. H. Mutechler P. Q. Nelson R. A. Nelson M. A. Oman S. Palmer A. F. Phillip* L. L. Preston E. L. Raab D. A. Roach R. E. Russell L. J. Savio R. L. Schmid R. L. Schwab L. R. Smith A. L. Tanlon R. C. Thomas D. E. Trust R A. Witch F. J. Vogel 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 HONS 091647 Contents SECTION 1. Scope and Introduction.................................................................. 2. General Characteristics of Askarei.......................................... PACK 5 5 3. Evaluation of Askarei Received in New Equipment................... 4. Classification of Service-Aged Askarei..................................... 6 6 5. Economic Factors............................................................................ 7 6. Sampling................................................................................... 7. Askarei Tests and Their Significance 7 g B, Testing Procedures.......................................... 8.1 Field Screening.................................................................. 8.2 Laboratory Screening...................................................... 9. Reconditioning and Reclaiming Service-Aged Askarei........................ 9.1 General............................................................... 9.2 Treatment After Exposure to an Arc................................. 9.3 Filtering Through Dry Blotter Paper to Remove Moisture and Extraneous Particles.......................................... 9.4 Fuller's Earth Treatment for Maximum Improvement of Power Factorand Volume Resistivity.......................... 9.5 Addition of Scavengers.............................................................................. 10 10 10 10 10 10 11 11 11 10. Handling Materials............................................................................................... 11. Askarei Used Under Mild Arcing Conditions.............................. 11 12 12. Askarei Under Excessive Temperature or Fault Conditions............ 13. Recommended Handling Precautions.............................. 12 12 14. Storage, Handling, and Disposal................................................... 14.1 Drums....................................................................................... 14.2 Tank Cars.......................................................................................... 14.3 Sampling ........................................................ 14.4 Effect of Light Exposure................................................ 14.5 Disposal............................................................................................. 16. Underwriters'Laboratories Reports........................................ .. 13 13 13 13 13 13 13 Appendix: Results of Survey of United States and Canadian Users of Transformer Askarei Al. General............................................................................................ A2. Testing.................................... A3. Reconditioning .............................. A4. Frequence of Testing............................................................ if) 13 13 16 16 TABLES Table 1 Acceptable Characteristics of Askarei in New Equipment Table 2 Askarei Tests to Determine Classification...................... 7 9 HONS 091848 IEEE Guide for Acceptance and Maintenance of Transformer Askarel in Equipment 1. Scope and Introduction The term askarel generally describes a wide ly used broad class of nonflammable synthetic halogenatcd 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 PCB's (poly chlorinated 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 PCB's are widely dis persed throughout the environment and that they can have adverse ecological and tox icological effects. The Federal Interdepartmental Task Force report COM-72-10419, "Polychlorinated Bi phenyls and the Environment," dated May 1972, has recommended restricting PCB's to use in transformers and capacitors. Methods for handling and disposal of askarels and askarel-impregnated materials are given in Draft American National Standard, Guidelines for Handling and Disposal of Capacitor and Transformer-Grade Askarels Containing Polychlorinated Biphenyls, C107.1. This guide assists the power equipment op erator in evaluating askarel as received in transformers, reactors, and accessory 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 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 other 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 gaB space with dry nitrogen before any work is performed on the apparatus. Askarel 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 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 askarel 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 transfer 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 axes and responsive to orientation by electrical forces. Askarel also exhibits a much higher dielectric constant and capacitance than insulating oil, and these difference# must 5 MQNS 0916*9 IEEE Sid 76*1974 IEEE GUIDE FOR ACCEPTANCE AND MAINTENANCE OF be kept in mind when interpreting electrical test data. Because 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 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 sensitive. 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 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 mineral 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 quite 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 in ap paratus. extreme care must be exercised in or der to obtain a representative sample. ASTM Standard D 923-70 (ANSI C69.2M973), Sam pling Electrical Insulating Liquids.1 should be followed. New equipment with askarel exhibiting the characteristics given in Table 1 is considered acceptable. The 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 askarel. 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, such 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 I. This group contains askarel which is in satisfactory condition for continued 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 III. This group contains askarel in poor condition. It should be reclaimed 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 fuller's earth is most widely used.) Group IV. This group contains askarel in such poor condition and requiring such dras- 'ASTM Standards referred to in this guide are ob tainable from Headquarters, American Society for Teeling and Materials, 1916 Race Street, Philadelphia, Pa, and from the American National Standards Institute. 1430 Broadway, New York. NY 10018. HONS o<ns50 TRANSFORMER ASKAREL IN EQUIPMENT Table 1 Acceptable Characteristics of Askarel in New Equipment IEEE Sid 76-1974 Characteristics ASTM Standards Dielectric breakdown voltage Color Visual condition Water content Power factor at 25 C 30 kV minimum 300 maximum (straw color) clear 3,1 parts per million max D 877-67 (1971) (ANSI C69.19-1968) (R1973) D 2129-64 (1969)(ANS1 C59.114-1970) D 1702-66 (1971) (ANSI C59.104 1970) D 1533-61 (1969) (ANSI C59.53 1963 (R1969)) D 924-68 (1969) (ANSI C69.22 1967) (R1973) D 150-70 The power factor of askarel taken from new transformers, reactors, and accessory equipment can reflect the presence 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-soHd insulation and to the high solvency power of the askarel. Qiven an acceptable water content and dielectric breakdown voltage of the askarel as indicated above, a high power factor seldom impairs the serviceability of the askarel within rather broad limits and ia indica tive of the degree of contamination present. Recognizing the possibility of a wide range of power factors being recorded for askarel in new oquipment, 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 25 C and 60 Hz do not in general indicate any abnormnl contamination providing that the other criteria (water 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 economically 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 askarel 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 hop facilities, whether the work is performed at one central or several distant locations, and the availability of qualified personnel. Askarel that contains water and insoluble contaminants can be reconditioned by me chanical means using various filter devices. If soluble or colloidal contaminants, or both, are present in the askarel, reclaiming can be done with special filtering devices or a special filter press using a material such as fuller's earth. To determine if reconditioning or reclaim ing of askarel is economically justifiable, a number of factors must be considered. Some of these factors are as follows: (1) Value of askarel being considered for processing (2) Cost of processing materials (3) Total cost of process versus quality of end product (4) Equipment maintenance and amor tization (5) Cost of collection and storage (6) Labor and transportation costs (7) Laboratory cost (8) Loss of askarel during processing (9) Cost of scavengers and makeup of chem icals if addition is necessary and desirable (10) Cost of disposing of processing material and scrap askarel (11) Cost of new askarel delivered at job site 6. Sampling Representative samples, whether of the complete contents or only parts thereof, are extremely important from the standpoint of evaluation of the quality of the product sam pled. Obviously careless sampling procedure or contamination in the sampling equipment will result in a sample that is not truly repre- 7 MONS 091851 IEEE Sid 761974 IEEE GUIDE FOR ACCEPTANCE AND MAINTENANCE OF tentative. Thia generally leads to erroneous conclusions concerning quality and incurs loss of time, effort, and expense involved in se curing. transporting, and testing the sample. It is strongly recommended that all of the pro cedures and precautions outlined in ASTM D 923-70 (ANSI C59.21-I973) or in the latest revision thereof approved by the American National Standards Institute be followed. Because of the high specific gravity (relative density) of askarel (greater than 1), water and some other impurities are most likely to be found at or near the surface. The top sample, therefore, is considered to represent the worst condition. 7. Askarel Tests and Their Significance There are a number of tests that can be ap plied to askarels as a basis for their classi fication as indicated in the foregoing. These tests and their significance are given in Table 2. (1) Color. The color of askarel is represent ed by a numerical value based on comparison with a series of numbered color standards with transmitted light under prescribed con ditions. Color is chiefly significant as an in dicator of contamination in askarel. Fre quently this contamination is the result of sol vent action between the askarel and other ma terials in the apparatus involved. No definite relationship can be established between color and the physical and electrical characteristics of the liquid. (2) Dielectric Breakdown Voltage. The di electric breakdown voltage of askarel may be defined as the voltage at which electrical breakdown of the material occurs under pre scribed conditions. The dielectric breakdown voltage of askarel is of importance as a mea sure of its ability to withstand electrical stress without failure. It may also indicate the pres ence of contaminating materials, such as wa ter. conducting particles, dissolved con taminants, or the decomposition products re sulting from an electric arc. A high dielectric breakdown voltage, however, is not a certain indication of the absence of all contaminants. (3) Flash and Fire Point. The flash point of askarel is the temperature to which askarel must be heated in order to give off sufficient vapor to form a flammable mixture with air under the conditions of the test. Askarels have a flash point which is not indicative of a haz ardous condition unless followed by a fire point. The fire point of a material that emits com bustible vapor may be defined as the temper ature to which the material must be heated in order to support continuous combusion when exposed to the atmosphere under prescribed conditions. Askarels have no fire point. The test is only of value, therefore, in showing whether the material has the nonflammable characteristics required of an askarel, or has a large amount of combustible contaminant. (4) Inorganic Chlorides. In the presence of water, chlorides can ionize. Their corrosive action can then be detrimental to the life of the apparatus in which the askarel is used. The presence of ionizable chlorides may be in dicative of arc decomposition of the askarel. (5) Neutralization Number. In the in spection of new askarels, the neutralization value is of importance as a quality index of purity. Since askarel is not subject to deterioration by oxidation, small changes in the neu tralization value of service-aged askarels may indicate the solution of basic or acidic materi als from the various solid materials in contact with the askarel or the deterioration of such soluble materials to form basic or acidic mate rials. A large change in acidity may indicate decomposition of the askarel by an electric arc. (6) Pour Point. The pour point of askarel may be defined as the temperature to which the liquid just flows under prescribed condi tions of test. The pour point has little signifi cance as far as contamination or deterioration is concerned but may be used for type identi fication. (7) Power Factor. Power factor is the ratio of the power dissipated in the askarel in watts to the product of the effective voltage and cur rent in volt-amperes, when tested with a sinu soidal field under prescribed conditions. Since askarel is not subject to oxidation, an increase of power factor value of the askarel in service may be attributed to the presence of moisture, dissolved polar compounds, or other con taminants. Depending upon the type of ap- MO NS 091852 TRANSFORMER ASKAREL IN EQUIPMENT Table 2 Askarel Tests to Determine Classification IEEE Sid 76-1974 Tests A6TM Standards {1) Color (2) Dirlrctric breakdown voltage (3) Flash and fire point (4) Inorganic chloridps (5) Neutralisation number (6) Pour point (7) Power factor (8) Refractive index (9) llcaislivity (specific resistance) (10) Scavenger content {) J) Specific gravity (relative density) (12) Viscosity (] 3) Visual examination of service-aged askarels in the Held (14) Volume of oil in oil-contaminated askarel (15) Water content D 21 29 64 (J969)(ANSI C59.114-1970) D 877-67 (1971 MANSI C59.19-1968 (R1973)) D 92-7 2 D 1821-63 (1969)(ANSI C59.55-1963 (R1969)) D 974-64 (1968XANS1 211.131-1964 (R197I)) D 664-58 (1968)(ANSI 21 J.59-1958 (R1971)) D 97-66 (1971 MANSI Zll.5-1966 (R1972)) 0924-66 (1969)(ANSI C69.22-1967 (RI973)) D 150-70 D 1807-64 (1969)(ANS1 C59.105-1970) D 1169-64 (1969)(ANSI C59.5I-1965 (R1969)) D 1701-69 D 1810-63 (1970) (ANSI C59.68-1965 (R1969)) D 88-56 (1968)(ANSI ZI1.2-1956 (R197!)) D 445-72 (ANSI Zl 1.107 1973) D 1702-66 (1971)(ANSI C59.104-1970) D 1808-63 (1969MANSI C59 67-1 965 (R1969)) D 1533-61 (1969)( ANSI 059.33-1963 (R1969)) paratus and application, high power factor due to contamination other than moisture sel dom Impairs the serviceability of the askarel. However, the high power factor may influence the transformer winding power factor. (8) Refractive Index. Refractive index is de fined as the ratio of the velocity of light in air to its velocity in the substance under pre scribed conditions. The refractive index of askarel varies with its composition and with the nature and amount of contaminants held in solution. Changes of refractive index of ask- are) in service may be useful in estimating compositional change and degree of soluble contamination. (8) Resistivity (Specific Resistance). Vol ume resistivity (specific resistance), in ohmcentimeters, of askarel is the ratio of the dc potential gradient in volts per centimeter par alleling the current flow within the sample to the current density in amperes per square cen timeter at a given instant of time and under prescribed conditions. The resistivity of ask arel is a measure of its electrical insulating properties. High resistivity normally reflects low content of free ions and ion-forming parti cles and indicates a low concentration of con ductive contaminants. (10) Scavenger Content. Askarels are de composed by an electric arc with the evolution of hydrogen chloride gas. A scavenger, which reacts chemically with dissolved hydrogen chloride gas to form a nonvolatile reaction product, may be added to an askarel and serves a useful function in improved preserva tion of the submerged portion of the ap paratus should an arc occur. Measurement of scavenger content indicates the amount of protection available against dissolved arcformed gases and permits estimation of the amount of makeup additive required. (11) Specific Gravity (Relative Density). The specific gravity (relative density) of an askarel is the ratio of the weights of equal vol umes of askarel and water at 16.56* C. Specif ic gravity (relative density) may be useful for type identification or to determine marked compositional changes. (12) Viscosity. The viscosity of an askarel is its resistance to uniformly continuous flow, without turbulence, inertia, or other forces, and is usually determined by measuring the time of flow of a given quantity of liquid under controlled conditions. Viscosity of askarels varies with temperature, and for that reason is always designated at a specified temper ature. Viscosity is a controlling factor in the dis sipation of heat by convection in insulating and cooling liquids. This is particularly im portant in transformers and other apparatus where heat generated in windings and cores must be largely removed by transmission through the liquid to a heat exchanger or the containing case. It is also a factor in the rate of impregnation of certain apparatus. 9 MOMS 091853 IEEE Bid 76 1971 IEEE GUIDE FOR ACCEPTANCE AND MAINTENANCE OF (13) Visual Examination of Service-Aged Askarels in the Field. This method provides for field examination of service-aged askarels, sampled from equipment in service, chiefly for the purpose of determining whether labora tory tests are required. This method may be of significance in visually detecting cloudiness which is an indication of the presence of mois ture, carbon particles, which may show an arcing condition, or color which is chiefly sig nificant as an indicator of contamination in askarels. No definite relationship has been es tablished between color and the physical and electrical characteristics of the liquid. By the use of this method it may be possible to extend the period between routine laboratory tests. (14) Volume of Oil in Oil-Contaminated Askarel. The quantitative determination of the volume of oil in oil-contaminated askarel is important as a check on the degree of con tamination and as a means of ascertaining when the nonflammable property of this fluid has been impaired to such an extent that it can no longer be classified as a nonflammable liquid. (15) Water Content. The water content is that amount of water, expressed in parts per million by weight, which is present in the liq uid. The test is significant in that it will show the presence of water which may not be evi dent from electrical tests. Changes in water content of askarel in service may be indicative of undesirable operating conditions requiring correction. 8. Testing Procedures The testing of askarels is best accomplished in adequately equipped laboratories. How ever, tome find it advantageous to make field screening tests. g.l Field Screening. Field screening tests are usually made to determine which samples of askarel may require laboratory investigation. Since most tests of askarel can be done best with laboratory equipment and trained per sonnel, field tests are usually limited to visual inspection and dielectric breakdown voltage. No standardized procedure is available at the present time for performing field tests on service-aged askarel or for classification. Port able dielectric test sets have been available for some time and have proved satisfactory. In addition to the preceding tests, some oper ators with suitable field equipment and trained personnel may wish to gain additional information by use of a power factor test. In interpreting results of these tests, consid eration must be given to other characteristics of the askarel. 8.2 Laboratory Screening. Askarel requiring laboratory evaluation will vary widely in con dition, depending upon the degree of con tamination. There are many tests of a re search nature which could be applied, but the general use of such tests would be impractical. The following tests, therefore, are believed to be adequate for classifying service-aged ask arel: (1) Dielectric breakdown voltage (2) Inorganic chlorides (3) Neutralization number (4) Power factor or resistivity (specific re sistance) (5) Specific gravity (relative density) (6) Visual condition and color (7) Water content 9. Reconditioning and Reclaiming Service-Aged Askarel 9.1 General. Askarel does not oxidize, sludge, or decompose in normal transformer use. It will break down when subjected to an elec trical arc. If the arc exposure has been of long duration, it is usually best to discard the fluid. However, when arc exposure has been rela tively mild or if the askarel is merely con taminated with moisture and other con ducting impurities, restoration is practical. An exception is the lack of a practical method for removing mineral oil from askarel. Askarel contaminated with over 2 percent by volume of transformer mineral oil may no longer be classified as a nonflammable liquid. 9.2 Treatment After Exposure to an Arc. When askarel is exposed to arcing, hydrogen chloride gas is liberated. Some hydrogen chlo ride will remain dissolved in the askarel and must be removed as quickly as possible. This is done by bubbling about 220 ftJ (6.23 m3) (1 cylinder) of dry nitrogen through each 100 gal (3.785 m3) of askarel. The nitrogen 10 MQNS 091854 TRANSFORMER ASKAREL IN EQUIPMENT IEEE Stri 76-1974 should be admitted at the bottom of the tank or container vented sufficiently to allow the nitrogen to escape, while preventing entrance of moisture. This procedure for removing hydrogen chloride iB recommended even though the askarel contains a hydrogen chlo ride scavenger. 9.3 Filtering Through Dry Blotter Paper to Remove Moisture and Extraneous Particles. Since undissolved moisture will be at the sur face of the askarel, any simple means should be used to drain or siphon off excess water. The final drying is done by circulating the askarel through dry blotter paper. The askarel temperature should not exceed 60 C. Several passes through multiple layers of freshly dried paper may be required. Filtering should not be done when the relative humidity exceeds 75 percent. The filter paper must be dried immediately before use. For best results, the paper is spread for maximum surface exposure in a hot air cir culating oven and heated for 4 to 6 h at J10*C. After filtration the dielectric breakdown voltage of the askarel should be at least 35 kV. 9.4 Fuller's Earth Treatment for Maximum Improvement of Power Factor and Volume Re sistivity. The askarel should be relatively dry prior to final refinement with conditioned fuller's earth. Most operators prefer a portable fuller's earth refining apparatus such as a plate press or an earthen cartridge type filter. As this ap paratus involves recirculation, the askarel should be removed from the top of the tank and returned at the bottom, because free mois ture and most of the other undissolved con taminants will be found near the surface of the askarel. Since these recirculating proce dures can introduce air into the askarel, suf ficient time (at least 4 h and preferably over night) should be allowed for the air to escape before re-energizing the apparatus. When a filter press is used, the plates are fit ted with dry filter paper. This is coated with 0.1 to 0.2 percent by weight of dried fuller's earth based on the weight of askarel to be treated. (Askarel weighs nearly 13 pounds per U. S. gallon, 1656 kg/m\) The finely divided clay should be activated and dried to not over 1 percent of moisture by heating for 12 h in shallow trays at about 200* C, immediately prior to use. To deposit the fuller's earth evenly, about one-third of the total quantity is stirred into a small portion of the askarel in a clean con tainer. This mixture is pumped through the filter, then followed with two more one-third portions. Then the askarel is pumped from the top level of the tank, through the filter, and returned to the tank at the bottom. It is desirable that the askarel temperature not ex ceed 60C during the filtering operation. Circulation is continued until the fluid is clear and tests show that the electrical proper ties are fully restored. 9,5 Addition of Scavengers. Only slight loss (by selective absorption) of the hydrogen chlo ride scavengers occurs when askarel is refined by treatment with 0.2 percent by weight of fuller's earth at a temperature not above 60*C. Significant removal of the additives can result from treatment with much larger amounts of fuller's earth. Initially 0.1 to 0.2 percent by weight of scavenger, usually an epoxide, is incorporated in modern transformer askarel. Inquiries about replenishing the additive should be di rected to the transformer manufacturer, or to the supplier of the fluid. 10. Handling Materials All common metals are satisfactory for use with askarel in dry environments. To avoid rust, it is preferable to use stainless steel or aluminum for filter presses or equipment used intermittently or in the presence of moisture. Because stainless-steel piping may be diffi cult to fabricate, the use of aluminum or gal vanized steel is more common. Pipe connections should be welded wherev er possible. Flanged connections are very good when fitted with a sufficient number of bolts to hold the gasket seal securely. Where readily removable connections are needed, deep pipe threads should be cut and wrapped with tetrafluoroethylene tape2 to make the seal. 'Such os Teflon. 11 MONS 091855 IEEE Sid 76-1974 IEEE GUIDE FOR ACCEPTANCE AND MAINTENANCE OF In addition to tetrafluoroethylene, other materials completely compatible with askarel and suitable for gaskets are certain elasto mers ' and stainless-steel rings with an accept able elastomer4 between the steel laminations. Silicone elastomer does not have good abra sive resistance and it is not suitable for use with mineral oil. Fluoroelastomers ' have rela tively good abrasion resistance and are resist ant to both askarel and mineral oil. If a fine-grain cork-nitrile rubber-com position gasket is used, it is desirable to coat the exterior of the seal with room-temperature curing epoxy cement or RTV silicone cement. Well-cured or dried adhesive cements of de waxed orange shellac, dextrine glue, polyvinyl alcohol acetate,'H phenolic or epoxy, are rela tively noncontaminating to askarel. Suitable hoses arc those of the flexible metal type, or those in which only tetrafluoroethylene**' or silicone polymers are in contact with the askarel. The preferred valves are those in which only stainless steel is in contact with the askarel. Where required, the stainless-steel valve may be seated with tetrafluoroethylene.* Also brass valves are acceptable. Asbestos graphite packing7 is suitable valve stem packing. Centrifugal pumps suitable for handling hot oil are the recommended type. Gear type pumps arc not desirable. All wetted surfaces of the pump should be of stainless steel. The shaft sea) should be the external mechanical (carbon ring) type to eliminate packing mate rial and its exposure to askarel. All askarel handling equipment should be reserved solely for use with askarel, and should not be used interchangeably with mineral oil. 11. Askarel Used Under Mild Arcing Conditions duction regulators, where operating switches are continually producing slight arcs, in transformer de-energizing switches, etc. Un der normal operating conditions, deteriora tion of the askarel is very slight. However, im properly adjusted or defective switches in this type of apparatus can produce excessive and prolonged arcing and accelerated deteriora tion of the askarel. It is recommended that when askarel is used under these conditions, checks of the liquid, especially for moisture and dielectric strength, be made more fre quently than when it is used only as a cooling and insulating fluid. Deterioration of this type is indicated by a blackening of the liquid. It can usually be reconditioned as previously described. Special attention should be given to maintaining the scavenger at the appropriate concentration. 12. Askarel Under Excessive Temper ature or Fault Conditions Chlorobenzenes used in transformer askarels begin to boil at temperatures of about 205*C under atmospheric conditions. If the material is heated to such high temperature in a sealed system, pressure develops. Pressure will also develop in the system if the askarel is arced sufficiently to generate copious hydro gen chloride gas. Therefore, it is recommended that wherever possible, sealed askarel-filled equipment be provided with pressure relief devices. These devices must be large enough to provide imme diate relief at a definite pressure, and to pre vent further buildup of pressure if decomposi tion continues. It must be remembered that the presence of devices of this sort does not necessarily preclude the rupturing of con taining vessels, since pressure buildup can be extremely rapid under violent arcing condi tions. Askarel is used, to some extent, in ap paratus where it is subjected to light, inter mittent arcing, such as in self-contained in 'Such Viton and Silastic. 'Such at Viton. 7'eflon, or silicone. `Such as Viton. *8urh as Elvanol. 'Such as number 117 braided Oarlock type, or Raybestos Manhattan type 365-C. 13. Recommended Handling Precautions It is generally accepted that the exposure to askarel is not hazardous, provided simple pre cautions are taken. Most people can handle askarel in the same manner as insulating oil without fear of adverse effects. Some people 12 MONS 091856 TRANSFORMER ASKAREL IN EQUIPMENT are allergic to askarel. and continued exposure may result in skin irritation. Therefore, direct contact with askarel and its vapors, particu larly when hot, should be avoided. This, com bined with personal cleanliness, should con stitute an adequate safeguard against harmful effects. Eye protection (glasses, shields, etc) are required. The use of any type glove should be avoided. Medicinal washes or detergents followed by an application of cold cream or sil icone-bearing hand lotions" have been suc cessfully used to eliminate irritation resulting from askarel coming into contact with an open cut or skin abrasion. A drop of castor oil has been found to neutralize, in most cases, ir ritation caused by contact of askarel with the eyes. Exposure to concentrated askarel vapors should be avoided, particularly in closed un ventilated rooms. As with many volatile liq uids, the vaporization of askarel increases rap idly with temperature. Therefore, ventilation which is adequate for handling askarel at room temperature may not be adequate for handling askarel at elevated temperatures. The gases produced when askarel is de composed by very high temperatures or an electric arc in the presence of air or organic in sulating materials contain a high percentage of hydrogen chloride and small percentages of carbon dioxide, carbon monoxide, and oxygen. Very small concentrations of this com bination of gases are very unpleasant and irri tating, thus giving ample warning of their presence. The all-purpose canister-type gas masks are suitable for protection from gases liberated from decomposed askarel. Itfc'fe' Scd 76 1971 Askarel must be kept dry. It can pick up moisture from contact with humid air. Drums of askarel should not be stored outdoors in an upright position, as water can collect in the dish of the drum head and can be drawn into the drum under certain conditions. Drums should be stored on their sides with the bungs downward and under cover. It is preferable to store drums indoors. Askarel should not be transferred into drums that have previously contained other materials. 14.2 Tank Cars. Tank cars are solid alumi num. or steel lined with aluminum, or a zinctin coating. It is desirable to provide canopies for un loading askarel cars. The car should not be opened in the rain or snow. It is desirable to not open the car if the relative humidity ex ceeds 75 percent. Precautions must always be taken to exclude dirt. 14.3 Sampling. See Section 6 for a discussion of sampling. 14.4 Effect of Light Exposure. Prolonged ex posure to ultraviolet light (sunlight, some flu orescent lights) should be avoided. Askarel can decompose under such conditions. Sample bottles are preferably of the amber glass type. 14.5 Disposal. Methods for disposal are given in Draft American National Standard, Guide lines for Handling and Disposal of Capacitor and Transformer-Grade Askarels Containing Polychlorinated Biphenyls, C107.1. 14. Storage, Handling, and Disposal 15. Underwriters' Laboratories Reports Transformer askarel can be handled in about the same manner as transformer miner al oil. 14.1 Drums. The askarel drum is made of steel lined with a specially selected material properly cured. Galvanized drums may also be used.* *Sucti as Silicare. The Underwriters' Laboratories have ex haustively examined, at the electrical manu facturers' requests, the miscellaneous hazards involved in the use of askarel and askarelfilled apparatus. Reports have been issued to the respective manufacturers covering the trade-named askarels being considered. It is suggested that interested users of transformer askarel contact the manufacturers for this in formation. HONS 091857 13 Appendix Results of Survey of United States and Canadian Users of Transformer Askarel (ThiN apiumdix in nol a part of IEEE Std 76-1974, IEEE Guide for Acceptance and Maintenance of Transformer Askarel in Equipment.) AX. General Thin survey of the United States and Can adian users of askarels was made in 1966 in or der to show the practices followed in testing, reconditioning, and reclaiming of askarels. Of the 96 inquiries sent out. 50 replies were re ceived with usable information, which is a 52 percent return. All of the following data are shown as a percentage of those returning the questionnaires and. it should be pointed out that this includes information from both manufacturers as well as users and no attempt has been made to classify them according to the size of the systems involved. Of the users of askarels who returned the questionnaire. 32 percent make only field tests; 32 percent make only laboratory tests; 24 percent make both field and laboratory tests; and 12 percent make no tests at all on askarels. Most all make tests at a fixed time interval and the largest group follow a yearly schedule. Of those users returning the ques tionnaire, 67 percent recondition askarel, which is below acceptable limits, and the most popular method employs the combination fuller's earth and blotter press. This survey was made purposely to deter mine the types of tests being made by askarel users and to give an. indication of acceptable limits. The following data are the overall re sults of the questionnaire. Al.l Field Tests for Askarel. Of askarel users, 66 percent do some type of field testing. Of these, 93 percent make a test for dielectric breakdown voltage. At least two field tests are made by 57 per cent as follows: (1) Dielectric breakdown voltage (2) Visual examination and color Other test* used in decreasing order of fre quency are power factor, neutralization num ber, and moisture. A1.2 Laboratory Testing for Askarel. Of ask arel users. 56 percent make an average of four tests in their laboratories on samples. Of these, 93 percent determine the dielectric breakdown voltage. At least four tests are made by 64 percent as follows: (1) Dielectric breakdown voltage (2) Color and condition (3) Neutralization number (4) Moisture content (5) Power factor Other tests used in decreasing order of fre quency are inorganic chlorides, resistivity (specific resistance), and specific gravity (rela tive density). A1.3 Askarel in New Equipment. Of the users, 80 percent test the dielectric breakdown volt age of askarel in new equipment. Also tested by 22 percent are the following: (1) Power factor (2) Moisture Other tests used in decreasing order of fre quency are neutralization number, inorganic chlorides, and resistivity (specific resistance). A2. Testing Most reporting companies test used askarels and approximately (1) 32 percent use only field tests (2) 32 percent use only laboratory tests (3) 24 percent use both field and laboratory tests (4) 12 percent do not test The relative importance of the field tests are as follows: (1) 93 percent dielectric breakdown voltage (2) 40 percent color and visual examination (3) 14 percent power factor (4) 11 percent neutralization number 15 HUNS 091656 The average limits on service-aged samples are as follows: (1) Dielectric breakdown voltage: average 27 kV, range 20 to 36 kV (2) Power factor: average 10 percent, range 2 to 40 percent (3) Neutralization number: average 0.12. range 0.06 to 0.5. (4) Inorganic chlorides: average 0.5. range 0.01 to 2.0 (6) Moisture: average 46 parts per million, range 40 to 66 parts per million The average limits on askarel in new equip ment are as follows: (1) Dielectric breakdown voltage: average 30 kV, range 22.5 to 35 kV (2) Power factor: average 3 percent, range 0.05 to f> percent. (3) Moisture: average 32.5 parts per million, range 20 to 50 parts per million A3. Reconditioning Of the users of askarel returning the ques tionnaire. 67 percent recondition askarel from transformers: (1) 73.5 percent prefer the combination full er's earth-blotter press (2) 17.5 percent use only the blotter press (3) 9 percent use only fuller's earth The average limits on reconditioned askarels, are as follows: (1) Dielectric breakdown voltage: average 29 kV. range 23 to 35 kV (2) Power factor: average 3.5 percent, range 2 to 15 percent (3) Neutralization number: average 0.10. range 0.01 to 0.5 (4) Moisture: average 35 parts per million, range 30 to 50 parts per million A4. Frequency of Testing The frequency of testing practiced by ask arel users is as follows: (1) 53 percent test every year (2) 17.5 percent test every 5 years (3) 17.5 percent test when there is a reason for testing (4) 9 percent test every 2 years (5) 3 percent test every 6 months Most users test all askarel units at the same interval regardless of rating. HONS 091859 16 PLEASE P tIN T To IEEE Standards Department ^ Please advise me when new editions of are issued. f Nani__ --. I Cnnipany I Address_____________ - --- -Zip- IEEE Std 76-1974 0 9 B T 6 0 SNOW FIRST CLASS MAIL Place Postage Hart STANDARDS DEPARTMENT The Institute of Electrical and Electronics Engineers 345 East 47th Street New York, N. Y, 10017 HONS 091861