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This information is provided as a service by Monsanto Chemical Company to help transformer users better understand the operating characteristics and maintenance procedures with askarel liquid insulation, and how these differ from mineral oil insulation. The information given on the following pages is based on facts Ii gathered by Monsanto during 30 years as producer of askarel. It represents knowledge gathered from the experience of transformer manufacturers and users over three decades. I Monsanto provides this information primarily as a guide on how to obtain maximum service with minimum reasonable maintenance of askarel dielectrics. All questions relating to the building and de signing of transformers should be referred to regular transformer suppliers. Morwmto gratefully acknowledge the aeeietance, guidance, and the contribution of certain data by the following: Frank M. Clark Edward L. Raab Jamas G. Ford George Sbombert, Jr. General Electric General Electric Wettinghouee Electric Allis Chalmers NEV Q765U 706902 ASKAREL - HISTORY OF TRADE NAME TYPES "Askarel" if the generic name for a special kind of liquid insulation that is completely different from ordinary transformer mineral oils. Askarel* liquid insulation -- whatever the trademarked brand --is all made from Monsanto's Aroclor 1260 (hexachlorobiphenyl) . . . one of the world's best liquid insulations. This inert compound is chemically stable, fire-resistant, heat stable, non-corrosive, and has high dielectric strength under the operating conditions encountered in askarel-type transformers. Monsanto manufactures Aroclor 1260 and formulates askarel liquid insulation to the specification of the various transformer manufacturers. Askarel liquid insulation is made by thinning Aroclor 1260 with trichlorobenzene or tri-, tetrachlorobenzene mix, and by the addition of a small amount of a chloride ' `scavenger" compound. The first transformer askarel was made in 1932, in accordance with General Electric Company's patents, and was trademarked Pyranol 1488. In '49, General Electric Company patented and began the use of 0.126% tin tetraphenyl scavenger additive, and this new askarel formulation was called Pyranol 1467. Westinghouse, too, offered an askarel insulation in 1933 under the company's trademark: Inerteen. The following table shows the composition and year of introduction of the two major types of askarel: Year Introduced ingredients! Aroclor 1260 Trichlorobenzene Tri-, tetrachlorobenzene mix Tin tetraphenyl Phenoxy propens oxide 14M 1932 60 40 Pyronol___________ 1447 1470 1949 1962 60 40 0.126 46 66 0.126 _____ inerteen Inerteen Inerteen MO 1933 1949 60 60 40 40 0.20 Other Brand Names Various manufacturers use other tradem arked names, like Chlorextol (Allis Chalmers); Noflamol (Wagner Electric); Asbestol (Amertran Corp.); Saf-T-Kuhl (Kuhlman Electric). These askarel insulating liquids are either one type or the other. Some manu facturers, who designate their insulation by the generic name askarel, assign a number or code so that Monsanto, when filling a particular company's order, knows whether to furnish Pyranol 1470 or Inerteen PPO type askarel. Commonly used for transformers. NEV 007651 706903 NEW 007652 706904 DIRECTIONS FOR HANDLING OF ASKAREL In handling, storing, sampling, inspecting askarel -- and in the operating of askarel transformers -- take every precaution to guard the askarel insulation from exposure to high humidity and moisture contamination. Keep 5, 30, or 55 gallon drums of askarel dry; turn them over on their sides to keep water off the drum head (it can be sucked in by the drum "breathing'*). Stability o f A ska n t Fluids Askarel liquid insulation is a very carefully-manufactured, highly pure, chemically made fluid. I t does not vary in composition like the range of mineral oils. A nd, askarel is heavier than water. I f water gets into the askard insulation, only a tin y amount (125 ppm ) dissolves -- the rest floats on top. A skard does not deteriorate when exposed to air, heat, hot metal; it does not break down over long use to form conducting or corrosive chemicals; it does not sludge or oxidize. A skard w ill remain perfectly stable year after year unless broken down by exposure to severe arcing. The only real "enemy" of askard is contamination by water. K eeping askard water-free w ill insure long-time service. In emergency, the two general types of askarel insulation can be either mixed or interchanged and there will be no difference in the operation of the transformer. Do not, however, mix askarel type insulation with mineral oil. NV 007653 706905 The two different types of askarel fluid sim ply differ in pour poin t and in the tin y amount of "scavenger" additive. The Pyranol type has the lower pour point; it w ill still pour at 470 below (F.) zero. The Inerteen type w ill pour down to 26 below (F.) zero. The different scavenger additives are both effective for absorbing hydrogen chloride -- which can be liberated from askarel if it is exposed to strong arcing. However, the additive in Pyranol type askarel can "crystallize" out at 149 above (F.) zero and looks like a hazy cloud in the liquid. I t does no harm; the crystals disappear after a while when the transformer warms up. This "haze" can be differentiated from water by a dielectric strength check. Generally there is no need to m ix or interchange; M onsanto supplies all types of askarel prom ptly -- anywhere in the world. Askarel should never be mixed with mineral o il because the core binding m aterials and p a in t suitable for oil-filled units soften and deteriorate in askarel. A nd, over 2% m ineral oil mixed into askarel begins to lower its fire resistance. USE ORDINARY PERSONAL PRECAUTIONS Transformer askarel has been made, handled, and used for over 30 years without causing toxic or other ill effects. It can be han dled with only minor precautions. If accidentally spilled on hands, serious skin irritation will not occur. However, the liquid has a sol vent action similar to paint thinner on the fats and oils of the skin and skin exposures may lead to drying and chapping. Eye contact may result in painful temporary irritation but no per manent damage to tissues. If it gets in the eyes, flush with large amounts of water. As with all eye first-aid, refer to a physician. To relieve irritation, physicians have used a 1% Pontocaine solution as well as opthalmic cortisone acetate solution. In case of contact, wash off the skin with soap and water; remove saturated clothing; clean up spills. * Infrequent exposure to askarel vapors will not cause any ill effects. However, prolonged exposure to high vapor concentrations should be avoided. If hot fluid must be handled in a closed or confined area, provide ordinary exhaust ventilation --or -- wear an organic car tridge respirator approved by the U. S. Bureau of Mines. NEV 007654 706906 CHECKPOINTS FOR INSPECTING AND MAINTAINING ASKAREL (oOVo U>l 706907 CHECKPOINTS ON MAINTAINING ASKAREL INSULATION Take All Possible Precautions to Keep Transformer Askarel Dry Whether askarel transformers are used indoors or outdoors -- the major maintenance checkpoint to assure virtually trouble-free operation is to eliminate possible contamination of the inside of the shell by moisture. (This is also true for oil-type units.) The following design information is provided as a guide for the frequency of inspection, for "modernizing" present units. .. and for ordering new equipment. (Your best source of specific design infor mation is your transformer supplier.) cover: Welded. When the entire transformer cover is welded onto, the body of the transformer, this avoids use of a gasket and eliminates "breathing" of humid air. gasketing: Use the proper gasketing for removable hand-hole openings. For maximum stability and fit, place the gasket in a recessed groove. Fine grain cork impregnated with nitrile rubber is suggested for gaskets. This type material is designated as NC757 by Armstrong Cork Co., Lancaster, Pa., and as M3150 by Wolverine Mfg. Co., Inkster, Mich. Suitable cement for this gasketing is dewaxed orange Bhellac, pigmented with iron oxide (available in pint size from Westinghouse, Sharon, Pa., Style No. 1150419). Nitrile rubber is sometimes used to seal the hand-hole. Because it is slowly attacked by askarel, this gasket must be recessed to allow minimum contact. Teflon, DuPont's Viton and most silicone "rub bers," while relatively expensive, warrant consideration for long term use requirements, at least for the smaller size gaskets. fins: Weld all fin connections. NEV 007656 706908 connection: Weld all major instrument or pipe connections. For incidental taps or nipples --above liquid --wrap the thread with Teflon tape: below liquid, seal threads with askarel-resistant cement, such as Westinghouse 6707-3 (a shellac base with special rubber filler). bushing connections: The most satisfactory bushings will be the type with rolled-on flanges with two ring seals rolled into a depression in the porcelain and sealed with silicone rubber rings held under compression. Metalto-glass or metal-to-porcelain sealed bushings are also satisfactory. Bushings on smaller size transformers (around 100 KVA) can be sealed with cork-nitrile rubber composition. nitrogen blanket: Blanket the " air space" above the askarel with dry nitrogen. If the transformer has so many leaks that pressure will not hold -- then bleed in a small amount of nitrogen steadily. Otherwise, "mod ernize" by welding. Another approach to "designing out'' moisture contamination: call for a "conservator" attachment so that the transformer shell is completely filled with the askarel. This eliminates the breathing of the air space. The liquid askarel level in the "conservator" is higher than the transformer cover; any water that would " seep" into the shell floats to the surface of the askarel in the conservator! drying breathers: Transformers not hermetically sealed, and designed to allow breath ing, should be fitted with a drying breather containing silica gel or anhydrous alumina. A detailed description of this drying arrangement for mineral oil units is contained in the booklet "Activated Alumina Maintenance Program" (1955, Aluminum Company of America, Pittsburgh, Pa). This approach is also suitable for askarel transformers. NEV 007657 706909 If desired -- although these factors are unimportant -- to keep power factor as low as possible and resistivity as high as possible, hang a container of anhydrous alumina in the circulating system of the transformer (askarel as well as mineral oil units). Cxpected Service Life end Importance of Moisture Protection Properly designed and installed askarel transformers w ill give trouble-free service for a minimum of 30 years. Since their introduction in 1932, the manufacturers report finding the over-all failure rate to be less than 0.5% for all units under test and service conditions. The Edison Electric Institute's report (1956-1958) on their member utilities publishes the failure rate for askarel transformers as 0.13 per hundred banks p er year! Even the rare reports of failure are invariably found to be due to im proper sealing that allows moisture to enter. The dielectric strength of askarel is highly sensitive to excess moisture; not sensitive to ordinary dissolved contaminants. W hile die dielectric strength can also be lowered by severe arcing, askarel turns noticeably black or has particles of sooty carbon floating in it if arcing has occurred. Unless severe arcing (internal electrical failure) has occurred, the dielectric strength is also the "moisture indicator." N ew askarel has a minimum dielectric strength of 35 K V at 25C.; a m axi mum moisture content of 30 ppm . I f the dielectric strength is checkedperiod ically and decreases significantly -- this indicates moisture pick-up, arcing, or both. When the dielectric strength has dropped to 2 2 K V or less, an analysis for water is necessary. I f water is found in excess of 100 ppm , its source should be located and corrections made. When the moisture content approaches 125 ppm (saturation level), the dielectric strength of askarel drops below the value required for efficient insulating. The moisture content should not be allowed to rise over 70 ppm ; it should be held as near as possible to 30 ppm . M aintaining a low moisture level w ill assure high dielectric strength and top operating efficiency. Relation of "Breakdown Strength" To Amount of Dlteolved Water In Askarel- and Mineral O il Water Content (PPM) 0 20 40 60 80 Breakdown Vottoge (ASTM) Aikarl Mineral Oil 70 K V 56 47 40 38 80 K V 39 30 26 22 NEV 007658 706910 Transform er A tk o rtl Sh ipp in g Specification* rfP p^ w l Pyuanol 1457 Pyronol 1470 ItMfttmrro Color, APHA Condition Water content, ppm (ASTM D1533-60) Acidity, mg. KOH/g. (ASTM D974-56) Dielectric Strength, 25*C., 0.1 inch gapJASTM D877-49) Dielectric Constant, 100*C., 1 KC (ASTM D924-49) Volume Resistivity, 100C., 500 volt# DC 0.1 inch gap 10* ohm-cm. Inorganic chlorides, pom. Refractive index, 25C. (ASTM D901-56) Viscosity at 37C. (ASTM D88-56) Saybolt Universal Seconds Pour point C. (ASTM D-97-57) Specific gravity 15.5/15.5C. (ASTM D287) Bum point (ASTM D92) 150 max. Clear 30 max. 0.01 max. 35 KV, min. 3.7 to 4.0 100 0.10 max. 1.6137 to 1.6147 54 2 --32 or lower 1.560 to 1.568 None to boiling 150 max. Clear 30 max. 0.01 max. 35 KV, min. 3.8 to 4.3 100 0.10 max. 1.6075 to 1.6085 41 to 45 --44 or lower 1.563 to 1.571 None to boiling 150 max. Clear 30 max. 0.01 max. 35 KV, min. 3.7 to 4.0 100 0.10 max. 1.6137 to 1.6147 54 2 --32 or lower 1.560 to 1.568 None to boiling Distillation range (ASTM D2056) corrected for stem and barometric pressure Fixed chlorine Corrosion test Color, APHA Acidity, mg. KOH/g. Inorganic chlorides ppm. Condition Scavenger content Arc formed gases 1st drop 40% 90% 200C. min. below 270C. 395 to 415C. 1st drop 35% 55% 65% 95% 210C. min. 240 to 256 290 to 330 385 to 400 395 to 415 1st drop 40% 90% 200C. min. below 270C. 395 to 415C. 59.1% min. 60.5 5% 59.1% min. After heating with aluminum for 6 his. a t 200 to 220C., the aluminum must not be corroded either on visual or weight inspection and the aakarel should meet the following specifications: 200 max. 200 max. 200 max. 0.01 max. 0.01 max. 0.01 max. 5.0 max. 5.0 max. 2.0 max. Clear Clear Clear 0.125% tin tetraphenyl 0.125% tin tetraphenyl 0.18 to 0.22% phenoxy propane oxide Leas than 1.0% of total combustible gases including carbon monoxide, hydrogen nd volatile hydrocarbons. NEV U 07659 r n CHECKPOINTS FOR INSPECTING ASKAREL INSULATION n Periodic Inspection c On a regular schedule -- at six, nine, or twelve month intervals make a simple visual inspection of your askarel insulation and run ! I a dielectric strength check. If dielectric strength has decreased r significantly from last inspection, or if it has gradually decreased to the 22-20 KV range (@ 25C.) -- RUN A CHECK FOR MOIS TURE. Use ASTM D901, D877. (Karl Fischer Method) WHA T CHECKPOINTS MEAN: Dielectric Strength The dielectric strength of askarel is the m ajor indicator to the operating efficiency of your liquid insulation and of the askarel transformer itself. besides the "visual" inspection tests -- the dielectric strength is the only test necessary to run on a routine basis. W ell-sealed askarel transformers have service records of 25 to 30 years on the original askarel. N ew askarel has a minimum dielectric strength of 35 K V a t 25C.; a maximum m ois ture content of 30 ppm . Visual Inspection: Color New askarel is a clear, faint-yellow liquid. After long-term use, this color may gradually intensify to light brown. Color Change Any color change such as taking on a green, red, or blue cast indi cates extraction. When distinct color pick-up is noted, the complete range of electrical characteristics should be checked to learn if extracted color is the tell-tale for contamination. Notwithstanding, color change alone is not a danger signal. When checking out a color change, the dielectric strength is by far the most important of the electrical characteristics; not the Power Factor or VolumeResistivity. Contamination H igh power factor and low volume resistivity in transformer m ineral oils are commonly regarded as "danger signals" that the oil has deteriorated i and broken down chemically. This is NOT TRUE of askarel liquid insulation. NEV Q07660 706912 New, unused askarel shows these electrical values: Power Factor: 0.05-0.2% @ 60 cyclee/20*C. (about 1-2.0% @ 60 cycles/100*0.) Volume Resistivity: 100-1000 X 10ohm-cm. (@ 100*0., 500 V., DC., 0.1' gap) Used askarel from S A T IS F A C T O R IL Y O PE R A TIN G T R A N S FORM ERS normally (and frequently) shows these values: Power Factor: 20 to 80% @ 60 cycles/100*C. Volume Resistivity: about 25 X 10' ohm-cm. (@ 100*C., 500 V., DC., 0.1' gap) This relatively high power factor and the relatively low volume resistivity of askarel sampled from normal operating transformers A R E TO B E E X P E C T E D . Even at these levels, the askarel's dielectric strength is E X C E LLE N T, S T IL L in the 30-35 K V range. The reason is sim ple: askarel, unlike m ineral oil, is a relatively polar liquid. W ith double the capacitance of mineral oil, askarel has greater dielec tric strength. A nd this property is the im portant factor for transformer insulation. Thus, the volume resistivity of askarel is more sensitive to traces of conductive contaminants than oil. However, even in the presence of large amounts of contaminants, the volume resistivity does not seem to fall below 5 x 1(P (ohm-cm). Y et the dielectric strength remains high, because in trin si cally askarel remains a non-conductor. Approximate Relationship Between Power Factor, Volume Resistivity, and Dielectric Strength of Transformer Askarel Power Factor (60 cyclat) 100C. 25C. 2% 6% 15% 20-25% 40-50% 0.05% 0.1% 0.7% 2.0% Volume fUilitivlty x 10* ohm-cm. (@ 100 C., 500 Volt DC., 0.1'flop) 1500 500 100 60-70 25 Dllctric Strength 25*C., 0.1 *gap >35 KV >35 KV >35 KV >35 KV >35 KV Clarity Inspect to make sure askarel remains clear in service. Development of turbidity or cloudiness indicates contamination from water, insulation particles, metallic dust, or dirt. Cloudiness or turbidity calls for complete analysis (unless the askarel is Pyranol 1470, sampled after extreme cold that has temporarily precipitated the "scavenger"). Heating to 150-200F. and agitating for a few hours will make this type of turbidity disappear; a dielectric strength (high result) check test will prove this white cloudiness is not water. NEV 007661 706913 Turbidity . . . m ay be the visual sign of water, or m ay indicate contamination from core m aterials, d irt, or deteriorating construction materials. Approximate Solubility of Wotsr In Transformer Askarel end Mineral OH Tempaseture Amount of Water (PPM) PI>olv<l J IC. Atkorol Mineral Oil -30 -22 8 8 -2 0 - 4 16 10 I -1 0 14 28 13 0 . 32 41 20 10 60 65 33 20 68 94 58 30 86 128 85 40 104 170 130 Effect of Common Insulation M aterials on Power Factor and Dielectric Strength (Heat Aged 96 hr. In Askarot @ 100 C.) Askerel After Exposure Power Factor, Dloloctrtc Forcent @60 Strength I Material Immerted None (control) Black varnished cloth eye., 100C 1.0 85.0 25C 36 KV 42 KV I Copper Preesbo&rd Manila paper 1.5 40 KV 2.0 37 KV 1.6 39 KV Bakelite 1.6 41 KV I Shellac Iron Synthetic rubber 6.0 36 KV 5.0 89 KV 70.0 39 KV I Iffe d of Common Insulation Materials on Volume Resistivity of Askarot I Volume Resistivity x 10* ehm-cm ( g 100C., 500 Volts Sample DC./ 0.1* gap) I 1. New askerel before heat aging 2. New askarel after heat aging 96 hre @ 100*C. 2,000 1,900 I 3. After heat aging with 1 aq. inch specimens of: a. Phenolic reain tap changer material b. Paper 1,200 760 c. Griule A press board (tan) 600 d. Grade A press board (gray) 600 o. Grade A press board, laminated strip 400 f. Cotton wrapping 300 g. Glyptal 1276 cement, cured 48 bra.@ 110*C. 100 H igh dielectric strength w ill quickly indicate that any turbidity present is not moisture; that the insulating efficiency ofdhe askarel is still excellent. W hile relatively high power factor and low volume resistivity are to be ex pected, when turbidity or a foreign color occurs these electrical values may confirm the askarel m ay be in contact with deteriorating construction m aterials. NEV 0 0 7 6 6 2 706914 Black Color and Carbon Particle* . . . show that askarel has *'`arced," especially if in the blackened liquid small particles of carbon can be seen. Askarel that has been exposed to arcing cannot be "refined" and should be discarded. To check the visual appearance chemically, dip moist blue litmus paper in sample. If paper turns red, the askarel has been arced beyond ability of the scavenger to capture the hydrogen chloride. Askarel Stability Askarel insulation is one of the most inert, chemically-stable, heat resistant, non-corrosive liquids known. I t w ill not break down, oxidize or sludge when exposed to a ir and high temperatures, 150C. or even somewha>higher. Arc ing, however, w ill break down the compound, to liberate some hydrogen chloride and sm all amounts of carbon. Approximate Competition Arc Formed G at From Trantformer Atkarel Oat Amount carbon monoxide carbon dioxide oxygen inert gase hydrogen chloride 0.3 per cent 0.3 per cent 0.6 per cent 1.5 per cent 97.3 per cent I t has been calculated and theorized that one kilow att of arc energy can pro duce about 135 cc. of gas of decomposition from askarel; compared with about 85 cc. of gas from m ineral oil. Moisture If the inspection sample of askarel shows 35-30 KV dielectric strength by the ASTM method, there is no need to check the moisture content. However, if dielectric strength has gone down to the 22-20 KV range, check for moisture using the Karl Fisher Method, ASTM D-1533. Dielectric Strength le Moisture Indicator The moisture content of new askarel is 30 parts per m illion maximum. The moisture saturation level is about 125 ppm at ordinary temperatures. When the moisture content approaches 125 ppm (saturation level), the dielectric strength goes down. The moisture content of askarel should not be allowed to rise over 70 ppm ; it should be held as near as possible to 30 ppm . Askarel's dielectric strength can be restored to the 35-30 K V range by sim ple refinement to take out the dissolved moisture. When the dielectric strength indicates it is tim e to refine the askarel, it is also tim e to inspect and get rid of any water accumulation in the transformer shell. NEV 0076J 706915 INTERPRETATION OF ASKAREL INSPECTION FINDINGS Judge the condition of your askarel insulation and the transformer on the basis of your visual inspection, the dielectric strength, and (when dielectric strength is found low), by the amount of the usually confirming high moisture content. Do NOT judge the conditions on the basis of the askarel's power factor or volume resistivity. High Power Factor and Low Volume Resistivity . . . in used oskarel is to be expected; these values are not an indication of chemical or electrical breakdown . . . even though such values often indicate m ineral oil's breakdown. Askarel and oil are two different chemical substances. A skard is (<compared to oil) a rd a tiv d y polar liq u id . . . highly sensitive to traces of ionizable im purities. The dielectric constant of new askard is about 4, nearly twice as high as mineral oil. Infinitesim al amounts of im purities from insulation, d irt, coatings can markedly in crease the power factor. (The same amount might not affect o il at all.) A nd further, unless critical care for cleanliness is taken in m aking the power factor test on askard -- the result can be erroneously still higherl W ith a power factor so sensitive and a test procedure so strict -- it is to be expected that when askard is p u t into a new transformer, the power factor w ill go up im m ediately on contact with the m aterials of construction. Authorities agree: the power factor of askard in use w ill be high, as much as 20-80% at 100C. and 60 eye. {about a tenth of this at 20C .). In service, the power factor of askard "goes up" to a greater extent than m ineral oil, but this -- in the absence of other "signals" -- has no significance. H igh power factor alone is not a danger sign with askard insulation I N A P R O P E R L Y CO N STR U C TE D TR AN SFO R M ER. However, high power factor in the absence of moisture in the shell, coupled with "turbidity" an d/or distinct foreign color, can indicate im proper con struction. Volume resistivity, too, m ay be expected to dedin e fa irly rapidly even in a norm ally operating transformer. I t should not drop below about 25 x 10* ohm-cm. and experience shows it w ill not drop below 5-10 x JO* even in the presence of heavy contamination, other than water. NV 0 0 7 6 6 4 706916 INSPECTION INTERPRETATION If askarel is clear, even though darkened to brown; has no sediment or turbidity; has dielectric strength over 25 KV . . . give it the inspection "OK". If askarel is clear; has foreign color of blue, green, red . . . it is "extracting color'* from internal materials. This is not, of itself, an operating hazard when the dielectric strength stays over 20 KV and moisture remains low. However, this rare occurrence calls for checking into condition of the interior construction and consulting the transformer maker. If askarel is clear; but dielectric strength drops to 22-20 KV, and moisture rises over 70 ppm . . . the askarel is ready for simple " refining". If dielectric strength has dropped to 22-20 KV or lower range; and if moisture is 115-125 ppm.. . the askarel is ready for refining. A thorough inspection should be made for water droplets in the transformer shell, and even for "globules" of water floating on the askarel surface. If found, mechanical means should be devised to protect the transformer from "breathing" moist air to prevent recurrence. If askarel is dark brown to black; if black particles of carbon are seen; and dielectric strength is low . . . the askarel has been broken down by arcing. It cannot be refined and should be discarded. If any of these five simple inspection tests appear out of the ordi nary or the relationship between appearance and test values is abnormal -- contact your transformer supplier for a complete analysis. Whenever a sample is to be shipped to the transformer manufac turer (or to Monsanto) for complete analysis, the container must be a 4 to 5-pint amber glass bottle. For your convenience, various transformer manufacturers and Monsanto will send you the sample bottle filled with new askarel. You simply empty out the new askarel and re-fill the bottle with your sample. Follow the directions shown under: " Sampling." NEV 007663 706917 WHAT TO DO . . . To minimize inspection end maintenance These sim ple tests will show you the condition of your askarel insulation, but only indirectly the condition of your transformer. They can be relied upon when your inspection sample is carefully taken (so as not to "m iss" moisture on the surface), I f you have taken mechanical precautions against moisture entry into your askarel transformer -- and can "keep it dry" -- these tests w ill be your assurance that, between checks, you can forget about maintenance. Check out: Is your transformer completely and hermetically sealed or does it have gasketed areas1 (Even the tightest gaskets can "breath".) Do you have a high fluctuating load? (Hot-to-cold temperature cycling makes the breathing faster and harder.) Is the a ir around your transformer cold and dry or hot and moist? When you have condensation from "breathing" and high hum idity -- you can guard against trouble by fitting the transformer with a drying device {all transformer makers offer these). Or you can bleed dry nitrogen or dry a ir through the "air space" above the askarel. The im portant thing to remember is that any mechanical steps you take to stop inside condensation w ill be double protection for troublefree operation. When buying equipment, specify whether transformers are intended for outdoor installation or w ill be used in a high moisture area. I f so, it's wise to p a y the only slightly increased cost for "designed-in" moisture protec tion; this w ill more than p a y for itself because askarel units, properly protected from moisture entry, w ill give trouble-free operation indefinitely. NEV 0 0 7 6 6 6 706918 SUPPLEM ENTAL ASKAREl DATA Sampling Askarsl Take a sample as close to the top of the liquid surface as possible. (Many large askarel transformers have a built-in sampling tube near the surface for convenient sampling.) Then to make sure that your SAMPLE truly represents your askarel insulation, take another sample from the bottom. If additional sampling tube con nections are contrived on the valves for easier sampling, make the tubes of clean glass, stainless steel, aluminum or tin for rigid types; and silicone or Teflon tubing for flexible types. Use NEW containers for the askarel sample. A new and previously unused small mouth pint glass bottle fitted with a Bakelite screw cap fitted with an aluminum or tin bottle cap liner is recommended. Be sure that the new bottle does not stand open to collect dust or moisture. Rinse the sample bottle and cap lining two or three times with askarel from the transformer; then fill it. If the sample will be tested promptly, a clear glass bottle can be used. If sample is to be stored indefinitely, use an amber glass bottle or wrap clear glass with aluminum foil. 1. Select a dry day. Do not sample insulation on a warm, moist day when humidity exceeds 75%, and . . . 2. Make sure that the askarel is at least as warm as the surround ing air. (Cold liquids can condense moisture from humid air.) Watar floats on askarel I f there is any water in your transformer, it m ay collect in little puddles O N TO P of the askarel. A nd therefore, more water w ill probably be dissolved in the askarel near the top, where it contacts any collected condensation. I f you find low dielectric strength and high moisture in the askarel, you w ill probably want to thoroughly dry out the core and coil structure and consult the manufacturer for instructions. When you take your askarel sample for testing, take the same precautions (but no more) that you would take when sam pling m ineral oil. N6V 0076oo 706920 Refining Askarel for Re-Uso Most operators prefer a portable refining apparatus, such as a plate press, fitted with a dolly, (available from Sparkler, Mundelein, 111.); or the earthen cartridge filter type, (available from Industrial Filter Corp., Lebanon, Ind.). Filter paper liners for the plate press are available from Carl Schleicher & Schuell Co., Keane, N. H. If you use a filter press, before refining it is advisable to oven-dry the filter paper at 110C. for 3 to 4 hours in an air circulating oven to remove all moisture. If the askarel to be refined contains exces sive moisture, circulate it hot (55-60C.) through the filter fitted with the paper liners only. After filtration the dielectric strength should be 35 KV., minimum. Precautions A n y flexible hoses and gaskets on the refining equipment should be lined with or made of m aterials that w ill not be softened by contact with askarel fluid. (Silicone or Teflon-lined, or flexible metal m aterials are suitable.) Quid to Rato of D istolvtd Water Removal by Filtering Askarel Through A Paper Press Passes Through Paper Press Water In Askarel PPM 0 116 1 36 2 22 3 18 4 12 5 10 6 10 NEV 007669 706921 Treatment for Maximum Improvement of Power Factor and Volume Resistivity Use Attapulgus clay or Fuller's earth, dried and activated by heating for 12 hours at 250F. immediately prior to use, as a coating on the filter surface. The amount of earth used should be 0.1 to 0.2 per cent by weight of the askarel (askarel weighs about 13 pounds per gallon). To deposit the earth evenly, stir one-third of the earth with a small portion of askarel in a clean container. Pump the mixture through the filter and follow with two more one-third portions. Then circu late askarel taken from near the top of the transformer, pass it hot (55-60C.) through the filter and feed back through the bottom transformer outlet. Continue circulation until the fluid is dear and shows the electrical properties are fully restored. Checking Transformer After Refining Askarel Fluid A fter refining the askarel, die over-all insulation resistances of the trans former should approxim ate the values for a new transformer filled with fresh askarel. I f the transformer insulation resistance is judged unsatis factory, die manufacturer should be contacted for complete inspection and analysis of the equipment. Effect o f Earth Refinement on Removal o f Scavengers Only tligh t and insignificant loss {by selective adsorption) of tintetraphenyl and phenoxy propene oxide occurs when askarel is refined by treatment with 0.1 to 0.2 per cent by tveight of earth. To remove significant amounts of the scavengers requires repetitious treatment with much larger amounts of earth. Amount of Tin-Totraphonyl Doptotlon From Pyronol 1470 By Roporttlout Trootmonl With Ono For Cont by Wolght of Earth _____ _____________ Tln-Ttfroph<nyl C o n t e n t ______ $omplt Original A ftor 4 treatments at ?0C. After 7 treatments at 90'C. No. 1 0.119% 0.018% 0.006% No. 2 0.107% A ftor 4 treatments at 60C. 0.021% After 6 treatments at 60C. 0.003% NEW 0 0 7 6 7 0 706922 NEV 007671 Inspection ChockPoints Color Clarity Moisture 25C. TYPICAL VALUES FOUND IN A SKAR EL INSULATION UNDER VARIO US CONDITIONS O F USE A New askarel a Askarel in properly* built new or rebuilt units prior to use. CD After normal oper Non-arced but ation; a survey of 50 slightly contami units, most 2-5 yra. nated askarel in old; some 10. improperly* built units, new or slightly used. E Same askarel as in Column D -- after refining. Light straw Clear, free from particles 30 ppm Light straw Light straw Clear, practically free from particles 30 ppm Clear, trace of particles 10-70 ppm all dissolved water Can have foreign shades, blue, green, red cast. Clear, slight amount of particles 20-100 ppm all dissolved water Foreign shades remain showing extraction of oil soluble color. Clear, free from particles 30 ppm Dielectric Strength 25C., 0.1' gap Volume Resistivity 100C.f 500 Volts, DC., 0.1' gap 35 KV minimum 35-48 KV 100 X 109ohm-cm. minifnnm usually 500-1,500 20 X 10* ohm-cm. mirnirmra usually at least 100 X 10* 35-45 KV 15-400 X 10* ohm-cm. 30-42 KV about 5 x 10* ohm-cm. 40-45 KV at least 1,500 X 10* ohm-cm. Power Factor: 100C. 60 cycles 25C. 60 cycles 2-5% 0.06-0.1% 10-25% 0.5-2% 10 to near 80% 0.5 to near 10% 30 to 100% about 7 to over 15% 2-5% 0.1-0.2% *A properly built transformer it defined as one in which the materials of construction are chemically and electrically compatible with askarel. F Heavily arced askarel due to neglect and internal electrical malfunction. Black Contains carbon particles Near 125ppm satura tion level-- plus pos sible undiasolved water 5-15 KV about 3 x 109 ohm-cm. 100% at least 25% CLEANING ARCED TRANSFORMERS If a unit has arced so that the askarel is no longer fit for use, a thorough cleaning of the unit is necessary before re-filling with new askarel insulation and returning it to service. Follow this procedure: 1. Drain out all dark, carbon-contaminated askarel. (Discard by dumping or burying where it will not contaminate a water supply.) 2. Wire brush carbon deposits from internal parts and insulation. 3. Flush thoroughly using new askarel (not an oil, not a cleaning solvent). 4. Wipe internal parts dry of askarel with lint free rags. 5. Flush a second time with fresh askarel; drain; then fill to the proper level with new askarel. 6. Energize transformer to warm the fluid for 24 to 48 hours; then circulate the askarel through a filter, returning it to the unit filtered and ready for use. NEV 00767? 706924 Tharmtti Condvetlvfty The thermal conductivity values of Pyranol 1470 at 27C. and 58C. are 26.2 and 25.8 x 10*8 calories centimeters**, degrees centigrade**, second*1, respectively. Or, approximately 0.06 BTU per (hr.) (sq. ft.) (F.) per-foot. Hut Capacity i Over the temperature range of 25 to 125C. the specific heat of transformer askarel is close to 0.30 calories per gram per degree. Coefficient ef Expansion The average coefficient of expansion of transformer askarel over the temperature range 20 to 100C. is 0.0007 cc/cc./C. One gallon would increase to 1.056 gallons on heating from 20 to 100C. Fire Resistance To use the generic name askarel the fluids must be approved by the Underwriters' Laboratories as possessing adequate fire resistance and freedom from forming explosive gases when arced. These liquids do not have a burn point (ASTM D92-33) (Cleveland open cup method) up to about 205C., at which temperatures they begin to boil. The significance of this is that they do not burn or support combustion under conditions encountered in transformer operation. Thus the danger of secondary explosion (or fire) is eliminated. Effect of Ttmptrafvrt on DiofectHc Strength of Aikorel *C DlfUctrtc Strength -6 0 67 KV -4 0 63 KV -2 0 67 KV 0 66 KV 20 60 KV 40 60 KV 60 48 KV 60 46 KV N EV 0 0 7 6 7;* 706925 ; Vapor Pressure of Pyranot 1467 and Inerteen PPO Temperature *C Vapor Pressure mm. Hg. 40 . - 60 80 100 120 140 1 4.9 9 36 60 90 Temperature C. -2 0 0 20 40 60 60 100 The Viscosity and Density of Pyranol 1447 and Inerteen PPO Type Askarel Viscosity Centlsfoket SayboH Universal Seconds 600 42 17 7.5 4.5 2.9 2.0 2,800 195 85 50 40 36 33 Density fm/cc. -- 1.574 1.552 1.529 1.507 1.485 Solubility of A ir and Wtropen In Transformer Atlcarol fircM ld WQ TOTav\tIWByIIV*Velum# JS*C 760 mm 0*C 760 mm 2S*C 100C. *S*C. 100C Air 6.3 5.5 5.8 6.0 Nitrogen 6.0 4.8 5.5 4.4 (When container of askant is heated rapidly from 26 to 100*C., no appreciable gassing ia observed.) Approximate Vapor Pressure vs. Temperature Per Transformer Askarel Temperature "C 40 60 80 100 120 140 Pyvanet 1447 and Inerteen PPO 1 mm H f. 6 mm H f. 9 mm H f. 30 mm H g. 60 mm H f. 90 mm H f . Pyrene! 1470 0.9 mm H f . 3.6 mm H f. 8.3 mm H f . 18 mm H f. 32 mm H f . 53 mm H f. NEV 007674 706926 Analytical Sarvicas on Transformer Askarel Available from Monsanto Transformer users not wishing to make their own fluid analysis can obtain these services from Monsanto. Simply contact Monsanto and specify what analyses are wanted. You will be sent the proper-sized sample container filled with fresh askarel. When you receive this, empty it and carefully take your sample (follow procedure for sampling in this guide) and send the container to Monsanto's laboratory. Chargee listed include sample container, shipping, handling and laboratory costs. TYPES OF ANALYSES AVAILABLE ANALYSIS 1) b) Earth Refinement ROUTINE MAINTENANCE CHECK Total Charge: $20.00 To determine the general condition of the fluid and find whether futher analysis is necessary. (one-quart sample required) Propertlei Tetd Color and Condition Dielectric Strength Moisture You will be notified of the results of this test. If further testing is indicated, and you want a complete analysis, you will be sent a five-pint sample container. This sample will be used for the following series of tests: ANALYSIS 2) COMPLETE ANALYSIS Total Charge: $50.00 (a) To determine the extent of fluid con tamination, (b) earth refinement to deter mine what degree of restoration of electrical and insulating properties is possible, (c) check test to see how the fluid responded to earth treatment. o) Complete Analysis: to determine the ex tent of contamination Properties Toted Color and Condition Specific Gravity Refractive Index Water Free Chlorides Acidity Dielectric Strength Power Factor, Dielectric Constant, and Resistivity Consists of treatment for 2.5 hours at 5060C. with 0.1 to 0.2 percent by weight of properly conditioned Attapulgus clay and then filtration through dry filter paper. e) Analysis After Laboratory Earth Refinement: Propertiei Tested Refractive Index Water Free Chlorides Acidity Dielectric Strength Power Factor, Dielectric Constant, and Resistivity You will be notified of the results of this test series on your sample. Then, after re fining your entire transformer fluid fill you can check on the results by requesting the following analysis: AN ALYSIS 3) ANALYSIS AFTER EARTH REFINEM ENT Total Charge: $30.00 (This charge will not apply when analyses 1 and 2 have already been made.) To determine whether the entire lot of askarel fill responded to the same extent as the laboratory sample, (five-pint sample required) Properliei Tsittd Color and Condition Refractive Index Water Free Chlorides Acidity Dielectric Strength Power Factor, Dielectric Constant, and Resistivity To arrange for the tests described above write to the following address: Paul G. Benignus Monsanto Chemical Company 800 North Lindbergh Blvd. St. Louis 66, Missouri Samples to be tested should be clearly marked for identification and sent directly to: Monsanto Chemical Company W. G. Krummrich Laboratory Monsanto, Illinois Attention: R. Kuster NV G7675 706927 ANALYTICAL SERVICES AVAILABLE I MONSANTO CH EM ICA L COM PANY ORGANIC CHEM ICALS DIVISION ST. LOUIS 66, M ISSOURI The information herein regarding obtaining optimum results from askarel fluids in your transformer has been accumulated by Monsanto for over 30 years from the experience of makers and users of askarel transformers and it is believed will be helpful. Nothing herein shall be construed as applying to other than askarel insulation. Data and maintenance suggestions herein do not apply to the other components of the transformer. All operating and main* tenance suggestions recommended by the manufacturer of the trans former should also be carefully followed. Because these maintenance directions applv only to the askarel Insula tion, Monsanto disclaims any liability for damage to property or injury to persons arising from transformer operation. 976 016} Utt*InU.9.A. NEV 0 0 7 6 7 6 706928