ASTM D117-22 Standard Guide for Sampling, Test Methods, and Specifications for Electrical Insulating Liquids

Referenced Documents2.1 ASTM Standards:2D92Test Method for Flash and Fire Points by ClevelandOpen Cup TesterD97Test Method for Pour Point of Petroleum ProductsD287Test Method for API Gra

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee Designation: D117 − 22 Standard Guide for Sampling, Test Methods, and Specifications for Electrical Insulating Liquids1 This standard is issued under the fixed designation D117; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision A number in parentheses indicates the year of last reapproval A superscript epsilon (´) indicates an editorial change since the last revision or reapproval 1 Scope Category Section ASTM Standard Dielectric Breakdown Voltage 17 D877, D1816, D3300 1.1 This guide describes methods of testing and specifica- Dissipation Factor and Rela- 18 D924 tions for electrical insulating liquids intended for use in electrical cables, transformers, liquid-filled circuit breakers, tive Permittivity (Dielectric 19 D7150 and other electrical apparatus where the liquids are used as Constant) insulating, or heat transfer media, or both Gassing Characteristic 20 D2300 Under Thermal Stress 21 D1169 1.2 The purpose of this guide is to outline the applicability Gassing Tendency of the available test methods Where more than one is available Resistivity 22 D1534 for measuring a given property, their relative advantages are Chemical Tests: 23 D2140 described, along with an indication of laboratory convenience, Acidity, Approximate 24 D3455 precision, (95 % confidence limits), and applicability to spe- Carbon-Type Composition cific types of electrical insulating liquids Compatibility with Construc- 25 D3635 tion Material 26 D7151 1.3 This guide is classified into the following categories: Copper Content Sampling Practices, Physical Tests, Electrical Tests, Chemical Elements by Inductively 27 D5837 Tests, and Specifications Within each test category, the test Coupled Plasma (ICP-AES) methods are listed alphabetically by property measured A list Furanic Compounds in 28 D3612 of standards follows: Electrical Insulating Liquids 29 D831, D1827, D2945 Dissolved Gas Analysis Category Section ASTM Standard Gas Content of Cable and 30 D664, D974 Sampling: 3 D923 Capacitor Liquids Physical Tests: Neutralization (Acid and 31 D2668, D4768 4 D611 Base) Numbers 32 D1934, D2112, D2440 Aniline Point Oxidation Inhibitor Content 33 D4059 Coefficient of Thermal Ex- 5 D1903 Oxidation Stability Polychlorinated Biphenyl 34 D1275 pansion 6 D1500 Content (PCB) 35 D1533 Color Sulfur, Corrosive Examination: Visual Infrared 7 D1524, D2144, D2129 Water Content 36 D3487 Flash and Fire Point Specification: Interfacial Tension 8 D92 Mineral Insulating Liquid for 37 D5222 Pour Point of Petroleum Electrical Apparatus 9 D971 Less Flammable Electrical 38 D4652 Products Insulating Liquids Particle Count in Mineral 10 D97, D5949, D5950 Silicone Fluid used for Electrical 39 D6871 Insulation Insulating Oil 11 D6786 Natural (Vegetable Oil) Ester Refractive Index and Specific Fluids used in Electrical 12 D1218 Apparatus Optical Dispersion Relative Density (Specific 13 D287, D1217, D1298, D1481, 1.4 The values stated in SI units are to be regarded as standard The values stated in parentheses are provided for Gravity) D4052 information only Specific Heat Thermal Conductivity 14 D2766 Viscosity Electrical Tests: 15 D2717 16 D445, D2161, D7042 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use It is the 1 This guide is under the jurisdiction of ASTM Committee D27 on Electrical responsibility of the user of this standard to establish appro- Insulating Liquids and Gases and is the direct responsibility of Subcommittee priate safety, health, and environmental practices and deter- D27.01 on Mineral mine the applicability of regulatory limitations prior to use Current edition approved May 1, 2022 Published June 2022 Originally 1.6 This international standard was developed in accor- published as D117 – 21 T Last previous edition approved in 2018 as D117 – 18 dance with internationally recognized principles on standard- DOI: 10.1520/D0117-22 ization established in the Decision on Principles for the Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959 United States 1 D117 − 22 Development of International Standards, Guides and Recom- D1534 Test Method for Approximate Acidity in Electrical mendations issued by the World Trade Organization Technical Insulating Liquids by Color-Indicator Titration Barriers to Trade (TBT) Committee D1816 Test Method for Dielectric Breakdown Voltage of 2 Referenced Documents Insulating Liquids Using VDE Electrodes 2.1 ASTM Standards:2 D1827 Test Method for Gas Content (Nonacidic) of Insulat- D92 Test Method for Flash and Fire Points by Cleveland ing Liquids by Displacement with Carbon Dioxide (With- drawn 2009)3 Open Cup Tester D97 Test Method for Pour Point of Petroleum Products D1903 Practice for Determining the Coefficient of Thermal D287 Test Method for API Gravity of Crude Petroleum and Expansion of Electrical Insulating Liquids of Petroleum Origin, and Askarels Petroleum Products (Hydrometer Method) D445 Test Method for Kinematic Viscosity of Transparent D1934 Test Method for Oxidative Aging of Electrical Insu- lating Liquids by Open-Beaker Method and Opaque Liquids (and Calculation of Dynamic Viscos- ity) D2112 Test Method for Oxidation Stability of Inhibited D611 Test Methods for Aniline Point and Mixed Aniline Mineral Insulating Oil by Pressure Vessel Point of Petroleum Products and Hydrocarbon Solvents D664 Test Method for Acid Number of Petroleum Products D2129 Test Method for Color of Clear Electrical Insulating by Potentiometric Titration Liquids (Platinum-Cobalt Scale) D831 Test Method for Gas Content of Cable and Capacitor Oils D2140 Practice for Calculating Carbon-Type Composition D877 Test Method for Dielectric Breakdown Voltage of of Insulating Oils of Petroleum Origin Insulating Liquids Using Disk Electrodes D923 Practices for Sampling Electrical Insulating Liquids D2144 Practices for Examination of Electrical Insulating D924 Test Method for Dissipation Factor (or Power Factor) Oils by Infrared Absorption and Relative Permittivity (Dielectric Constant) of Electri- cal Insulating Liquids D2161 Practice for Conversion of Kinematic Viscosity to D971 Test Method for Interfacial Tension of Insulating Saybolt Universal Viscosity or to Saybolt Furol Viscosity Liquids Against Water by the Ring Method D974 Test Method for Acid and Base Number by Color- D2300 Test Method for Gassing of Electrical Insulating Indicator Titration Liquids Under Electrical Stress and Ionization (Modified D1169 Test Method for Specific Resistance (Resistivity) of Pirelli Method) Electrical Insulating Liquids D1217 Test Method for Density and Relative Density (Spe- D2440 Test Method for Oxidation Stability of Mineral cific Gravity) of Liquids by Bingham Pycnometer Insulating Oil D1218 Test Method for Refractive Index and Refractive Dispersion of Hydrocarbon Liquids D2668 Test Method for 2,6-di-tert-Butyl- p-Cresol and 2,6- D1250 Guide for the Use of the Joint API and ASTM di-tert-Butyl Phenol in Electrical Insulating Oil by Infra- Adjunct for Temperature and Pressure Volume Correction red Absorp Factors for Generalized Crude Oils, Refined Products, and Lubricating Oils: API MPMS Chapter 11.1 D2717 Test Method for Thermal Conductivity of Liquids D1275 Test Method for Corrosive Sulfur in Electrical Insu- (Withdrawn 2018)3 lating Liquids D1298 Test Method for Density, Relative Density, or API D2766 Test Method for Specific Heat of Liquids and Solids Gravity of Crude Petroleum and Liquid Petroleum Prod- (Withdrawn 2018)3 ucts by Hydrometer Method D1481 Test Method for Density and Relative Density (Spe- D2864 Terminology Relating to Electrical Insulating Liq- cific Gravity) of Viscous Materials by Lipkin Bicapillary uids and Gases Pycnometer D1500 Test Method for ASTM Color of Petroleum Products D2945 Test Method for Gas Content of Insulating Oils (ASTM Color Scale) (Withdrawn 2012)3 D1524 Test Method for Visual Examination of Used Elec- trical Insulating Liquids in the Field D3300 Test Method for Dielectric Breakdown Voltage of D1533 Test Method for Water in Insulating Liquids by Insulating Liquids Under Impulse Conditions Coulometric Karl Fischer Titration D3455 Test Methods for Compatibility of Construction Ma- 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or terial with Electrical Insulating Oil of Petroleum Origin contact ASTM Customer Service at service@astm.org For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on D3487 Specification for Mineral Insulating Oil Used in the ASTM website Electrical Apparatus D3612 Test Method for Analysis of Gases Dissolved in Electrical Insulating Oil by Gas Chromatography D3635 Test Method for Dissolved Copper In Electrical Insulating Oil By Atomic Absorption Spectrophotometry D4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter D4059 Test Method for Analysis of Polychlorinated Biphe- nyls in Insulating Liquids by Gas Chromatography D4652 Specification for Silicone Liquid Used for Electrical Insulation D4768 Test Method for Analysis of 2,6-Ditertiary-Butyl 3 The last approved version of this historical standard is referenced on www.astm.org 2 D117 − 22 Para-Cresol and 2,6-Ditertiary-Butyl Phenol in Insulating placed in a tube and mixed mechanically The mixture is heated Liquids by Gas Chromatography at a controlled rate until the two phases become miscible The D5185 Test Method for Multielement Determination of mixture is then cooled at a controlled rate, and the temperature Used and Unused Lubricating Oils and Base Oils by at which the two phases separate is recorded as the aniline Inductively Coupled Plasma Atomic Emission Spectrom- point etry (ICP-AES) D5222 Specification for High Fire-Point Mineral Electrical 4.3 Significance and Use—The aniline point of an insulating Insulating Oils liquid indicates the solvency of the liquid for some materials D5837 Test Method for Furanic Compounds in Electrical that are in contact with the liquid A higher aniline point Insulating Liquids by High-Performance Liquid Chroma- implies a lower aromaticity and a lower degree of solvency for tography (HPLC) some materials D5949 Test Method for Pour Point of Petroleum Products (Automatic Pressure Pulsing Method) 5 Coefficient of Thermal Expansion D5950 Test Method for Pour Point of Petroleum Products (Automatic Tilt Method) 5.1 Scope—Practice D1903 covers the determination of the D6786 Test Method for Particle Count in Mineral Insulating coefficient of thermal expansion of electrical insulating liquids Oil Using Automatic Optical Particle Counters of petroleum origin D6871 Specification for Natural (Vegetable Oil) Ester Fluids Used in Electrical Apparatus 5.2 Definition: D7042 Test Method for Dynamic Viscosity and Density of 5.2.1 coeffıcient of thermal expansion—the change in vol- Liquids by Stabinger Viscometer (and the Calculation of ume per unit volume per degree change in temperature It is Kinematic Viscosity) commonly stated as the average coefficient over a given D7150 Test Method for the Determination of Gassing Char- temperature range acteristics of Insulating Liquids Under Thermal Stress D7151 Test Method for Determination of Elements in Insu- 5.3 Summary of Practice—The specific gravity of insulating lating Oils by Inductively Coupled Plasma Atomic Emis- liquids is determined at two temperatures below 90 °C and sion Spectrometry (ICP-AES) separated by not less than 5 °C nor more than 14 °C Test 2.2 ASTM Adjunct:4 methods used may be D287, D1217, D1298, or D1481 The Adjunct to D1250 Guide for Petroleum Measurement Tables calculation of average coefficient of thermal expansion over (API MPMS Chapter 11.1) this temperature range is given in Practice D1903 SAMPLING 5.4 Significance and Use—A knowledge of the coefficient of expansion of a liquid is essential to compute the required size 3 Sampling of a container to accommodate a volume of liquid over the full temperature range to which it will be subjected It is also used 3.1 Accurate sampling, whether of the complete contents or to compute the volume of void space that would exist in an only parts thereof, is extremely important from the standpoint inelastic device filled with the liquid after the liquid has cooled of evaluation of the quality of the product sampled Obviously, to a lower temperature careless sampling procedure or contamination in the sampling equipment will result in a sample that is not truly representa- 6 Color tive This generally leads to erroneous conclusions concerning quality and incurs loss of the time, effort, and expense involved 6.1 Scope—Test Method D1500 covers the visual determi- in securing, transporting, and testing the sample nation of color of a wide variety of liquid petroleum products, including mineral insulating liquids 3.2 Sample the insulating liquid in accordance with Prac- tices D923 as appropriate 6.2 Summary of Test Method: 6.2.1 Test Method D1500—The test specimen is placed in a PHYSICAL PROPERTIES glass sample jar (an ordinary 125-mL test specimen bottle is satisfactory for routine tests) The color of the sample by 4 Aniline Point transmitted light is compared with a series of tinted glass standards The glass standard matching the sample is selected, 4.1 Scope—Test Method D611 covers the determination of or if an exact match is not possible, the next darker glass is the aniline point of petroleum products, provided that the selected The results are reported numerically on a scale of 0.5 aniline point is below the bubble point and above the solidifi- to 8.0 cation point of the aniline-sample mixture 6.3 Significance—A low color number is an essential re- 4.2 Summary of Test Method: quirement for inspection of assembled apparatus in a tank An 4.2.1 Test Method D611—Equal volumes of aniline and test increase in the color number during service is an indicator of specimen or aniline and test specimen plus n-heptane are deterioration or contamination of the insulating liquid 4 Available from ASTM International Headquarters Order Adjunct No ADJ- 7 Examination: Visual/Infrared ADJD1250 Original adjunct produced in 1983 7.1 Scope: 7.1.1 Both visual examination and qualitative infrared ab- sorption are described in this section The test methods are: 3 D117 − 22 7.1.2 Test Method D1524—This is a visual examination of (9 °F ⁄min to 11 °F ⁄min) and apply the test flame every 2 °C (or mineral insulating liquids that have been used in transformers, 5 °F) until a flash occurs Continue heating and testing every liquid-filled circuit breakers, or other electrical apparatus as 2 °C (or 5 °F) until the liquid continues to burn for at least 5 s insulating or cooling media, or both The procedure is described in Test Method D92 7.1.3 Practices D2144—The infrared absorption from 2.5 to 8.4 Significance and Use—The flash point and fire point 25 µm (4000 to 400 cm−1) is recorded as a means of (a) tests give an indication of the flammability of a liquid They establishing continuity by comparison with the spectra of may also be used to provide a qualitative indication of previous shipments by the same supplier, (b) for the detection contamination with more flammable materials In the latter of some types of contaminants, (c) for the identification of context, the flash point test is more sensitive liquids in storage or service This practice is not intended for the determination of the various constituents of a liquid 9 Interfacial Tension 7.2 Summary of Test Methods: 9.1 Scope—These test methods cover the measurement, 7.2.1 Test Method D1524—The condition of the test speci- under nonequilibrium conditions, of the interfacial tension of men is estimated by observation of cloudiness, foreign insulating liquids against water These test methods have been particles, or suspended matter in the sample by reflected light shown by experience to give a reliable indication of the By use of this test method and Test Methods D1500 or D2129, presence of hydrophilic compounds the color and condition of a test specimen of electrical insulating liquid may be estimated during a field inspection, 9.2 Definition: thus assisting in the decision as to whether or not the sample 9.2.1 interfacial tension—the molecular attractive force be- should be sent to a central laboratory for full evaluation tween unlike molecules at an interface It is usually expressed 7.2.2 Practices D2144—The infrared spectrum is recorded in millinewtons per meter from 2.5 to 25 µm (4000 to 400 cm−1) either as the absorption spectrum itself, or as the differential between the test specimen 9.3 Summary of Test Methods: and reference liquid The spectra are compared with reference 9.3.1 Test Method D971—Interfacial tension is determined spectra to establish the identity of the liquid by measuring the force necessary to detach a platinum wire upward from the oil water interface To calculate the interfacial 7.3 Significance and Use: tension, the force so measured is corrected by an empirically 7.3.1 Practices D2144—The infrared spectrum of an elec- determined factor which depends upon the force applied, the trical insulating liquid indicates the general chemical compo- densities of both oil and water, and the dimensions of the ring sition of the sample Because of the complex mixture of The measurement is completed within 1 min of the formation compounds present in insulating liquids, the spectrum is not of the interface sharply defined and may not be suitable for quantitative estimation of components The identity of the liquid can be 9.4 Significance and Use—Interfacial tension measurements quickly established as being the same or different from on electrical insulating liquids provide a sensitive means of previous samples by comparison with the reference spectra detecting small amounts of soluble polar contaminants and products of oxidation A high value for new mineral insulating 8 Flash and Fire Point liquid indicates the absence of most undesirable polar contami- nants The test is frequently applied to service-aged liquids as 8.1 Scope: an indication of the degree of deterioration 8.1.1 Test Method D92 covers the determination of flash and fire points of all petroleum products except fuel oil and 10 Pour Point of Petroleum Products those having an open cup flash below 79 °C (175 °F) 8.1.2 This test method should be used solely to measure and 10.1 Scope—The pour point is applicable to any petroleum describe the properties of materials in response to heat and liquid flame under controlled laboratory conditions and should not be used for the description, appraisal, or regulation of the fire 10.2 Definition: hazard of materials under actual fire conditions 10.2.1 pour point—the lowest temperature, expressed as a multiple of 3 °C at which the liquid is observed to flow when 8.2 Definitions: cooled and examined under prescribed conditions 8.2.1 flash point—the temperature at which vapors above the liquid surface first ignite when a small test flame is passed 10.3 Summary of Test Methods: across the surface under specified conditions 10.3.1 After preliminary heating, the test specimen is 8.2.2 fire point—the temperature at which liquid first ignites cooled at a specified rate and examined at intervals of 3 °C for and burns for at least 5 s when a small test flame is passed flow characteristics The lowest temperature at which move- across the surface under specified conditions ment of the liquid is observed within 5 s is reported as the pour point The procedure is described in Test Method D97 8.3 Summary of Test Method—Fill the test cup to the 10.3.2 Test Method D5949 covers the determination of pour specified level with the test specimen Heat the sample initially point of petroleum products by an automatic instrument that at 14 °C ⁄min to 17 °C ⁄min (25 °F ⁄min to 30 °F ⁄min) until the applies a controlled burst of nitrogen gas onto the specimen temperature is 56 °C (100 °F) below the expected flash point surface while the specimen is being cooled and detects Reduce the rate of temperature change to 5 °C ⁄min to 6 °C ⁄min movement of the surface of the test specimen with an optical eye 4 D117 − 22 10.3.3 Test method D5950 covers the determination of pour 12.1.1 Test Method D1218—Describes a precise method for point of petroleum products by an automatic instrument that determining refractive index accurate to 0.00006 and refractive tilts the test jar during cooling and detects movement of the dispersion accurate to 0.00012 The liquid must be transparent, surface of the test specimen with an optical eye no darker than ASTM 4.0 color (see Test Method D1500) and have a refractive index between 1.33 and 1.50 The specific 10.4 Significance and Use: optical dispersion is calculated by dividing the refractive 10.4.1 The pour point of an insulating liquid gives an dispersion value by the specific gravity of the liquid indication of the temperature below which it may not be possible to pour or remove the liquid from its container 12.2 Definitions: 10.4.2 In connection with liquid for use in cable systems, 12.2.1 refractive index—the ratio of the velocity of light in the pour point may be useful to indicate the point at which no air to its velocity in the substance under test free movement will take place in the cable or to indicate the 12.2.2 specific optical dispersion —the difference between temperature at which partial separation of wax may occur the refractive indexes of light of two different wave lengths, 10.4.3 The pour point of an electrical insulating liquid is both indexes measured at the same temperature, the difference important as an index of the lowest temperature to which the being divided by the specific gravity also measured at the test material may be cooled without seriously limiting the degree of temperature For convenience, the specific dispersion value is circulation of the liquid Some materials are sensitive to multiplied by 104 temperature cycling or prolonged storage at low temperatures, and their pour points may not adequately predict their low 12.3 Summary of Test Method: temperature flow properties 12.3.1 The two methods differ in the accuracy of the refractometer used After adjusting the instrument temperature 11 Particle Count in Mineral Insulating Oil Using to 25°C, apply the test specimen to the refracting prism, read Automatic Optical Particle Counters the refractive index, and read the compensator dial reading From the correlation tables supplied with the instrument obtain 11.1 Scope—Test Method D6786 covers the determination the refractive dispersion Calculate the specific optical disper- of particle concentration and particle size distribution in sion by dividing refractive dispersion by the specific gravity of mineral insulating liquid It is suitable for testing liquids the liquid having a viscosity of 6 to 20 mm2/s at 40 °C The test method is specific to liquid automatic particle analyzers that use the 12.4 Significance and Use: light extinction principle 12.4.1 Refractive Index of an insulating liquid varies with its composition and with the nature and amount of contami- 11.2 Summary of Test Method: nants held in solution Where the refractive index of an 11.2.1 Samples are taken in particle-clean bottles that are insulating liquid when new is known, determinations made on suitable for particle analysis The sample bottle is agitated to the same liquid after periods of service may form a basis for redistribute particles in the liquid, then the liquid is placed in estimating any change in composition or the degree of con- an automatic particle counter, where the number of particles tamination acquired through service and their size distribution are determined by the light extinction 12.4.2 Specific Optical Dispersion serves as a quick index principle to the amount of unsaturated compounds present in a liquid As 11.2.2 As particles pass through the sensing zone of the the dispersion values for paraffinic and naphthenic compounds instrument, the quantity of light reaching the detector is are nearly the same and are essentially independent of molecu- obscured This signal is translated to an equivalent projected lar weight and structural differences, values above a minimum area diameter based on calibration with a NIST-traceable liquid of about 97 bear a direct relationship to the amount of aromatic (ISO Medium Test Dust suspension) compounds present in insulating liquid 11.3 Significance and Use: 13 Relative Density (Specific Gravity) 11.3.1 Particles in insulating liquid can have a detrimental effect on the dielectric properties of the liquid, depending on 13.1 Scope: the size, concentration, and nature of the particles The source 13.1.1 The methods used to measure relative density (spe- of these particles can be external contaminants, liquid degra- cific gravity) may use a hydrometer, pycnometer, or an dation byproducts, or internal materials such as metals, carbon, oscillating tube or cellulose fibers 13.1.1.1 Test Method D287—Uses an API hydrometer and is 11.3.2 Particle counts provide a general degree of contami- limited to liquids having a Reid vapor pressure of 180 kPa (26 nation level and may be useful in assessing the condition of psi) or less specific types of electrical equipment Particle counts can also 13.1.1.2 Test Method D1217—Covers the use of a pycnom- be used to determine filtering effectiveness when processing eter to measure the relative density (specific gravity) of liquid petroleum fractions 11.3.3 If more specific knowledge of the nature of the 13.1.1.3 Test Method D1298—Covers the use of a hydrom- particles is needed, other tests such as metals analysis or fiber eter to measure relative density (specific gravity) directly or the identification and counting must be performed measurement of API gravity followed by conversion to relative density (specific gravity) This test method is limited to liquids 12 Refractive Index and Specific Optical Dispersion having a Reid vapor pressure of 179 kPa (26 psi) or less This 12.1 Scope: 5 D117 − 22 test method is most suitable for use with mobile transparent neous single body of liquid Such conditions have caused liquids, although it can also be used with viscous liquids if serious overheating of self-cooled apparatus Suitable precau- sufficient care is taken in the measurement tions should be taken to ensure mixing 13.1.1.4 Test Method D1481—Covers the determination of 14 Specific Heat the densities of liquids more viscous than 15 mm2/s at 20 °C The liquid should not have a vapor pressure greater than 13 kPa 14.1 Scope—Test Method D2766 covers determination of (100 mm Hg) at the test temperature To measure the density of the specific heat of electrical insulating liquids of petroleum less viscous liquids more accurately than permitted by the origin hydrometer method, Test Method D1217 is available 14.2 Definition: 13.1.1.5 Test Method D4052—Covers the measurement of 14.2.1 specific heat (or heat capacity) of a substance—a relative density (specific gravity) by the measurement of thermodynamic property that is a measure of the amount of change in oscillation frequency of a vibrating glass tube filled energy required to produce a given temperature change within with test liquid a unit quantity of that substance The standard unit of heat capacity is J/(kg·°C) at some defined temperature 13.2 Definition: 13.2.1 relative density (specific gravity)—the ratio of the 14.3 Summary of Test Method—The specific heat is deter- mass (weighed in vacuum) of a given volume of liquid at 15 °C mined by Test Method D2766 The measurement is made by (60 °F) to the mass of an equal volume of pure water at the heating a test specimen at a known and fixed rate Once same temperature When reporting results, explicitly state the dynamic heating equilibrium is obtained, the heat flow is reference temperature, for example, specific gravity 15/15 °C recorded as a function of temperature The heat flow normal- ized to specimen mass and heating rate is directly proportional 13.3 Summary of Test Method: to the specimen’s specific heat capacity 13.3.1 API gravity may be measured at the liquid tempera- ture using a hydrometer (Test Methods D287 or D1298) or 14.4 Significance and Use—A knowledge of the specific Digital Density Meter (Test Method D4052) and converting to heat is helpful in designing adequate heat transfer properties 15 °C or 60 °F using adjunct to Guide D1250.4 for electrical apparatus A higher specific heat value indicates a 13.3.2 Relative density (specific gravity) may be measured more efficient heat transfer medium at the liquid temperature using a hydrometer (Test Method D1298) or by Digital Density Meter (Test Method D4052) and 15 Thermal Conductivity converted to 15 °C or 60 °F using adjunct to Guide D1250.4 13.3.3 Test Method D1481—The liquid is drawn into the 15.1 Scope—Test Method D2717 covers the determination bicapillary pycnometer through the removable siphon arm and of the thermal conductivity of electrical insulating liquids of adjusted to volume at the temperature of test After equilibra- petroleum origin tion at the test temperature, liquid levels are read; and the pycnometer is removed from the thermostated bath, cooled to 15.2 Definition: room temperature, and weighed Density or relative density 15.2.1 thermal conductivity—the ability of a substance to (specific gravity), as desired, is then calculated from the transfer energy as heat in the absence of mass transport volume at the test temperature, and the weight of the sample phenomena The standard unit of thermal conductivity is as The effect of air buoyancy is included in the calculation follows: 13.4 Significance and Use: W/ ~m·°C! 13.4.1 Electrical insulating liquids are usually sold on the basis of volume delivered at 15 °C (60 °F) Delivery is often 15.3 Summary of Test Method—The thermal conductivity is made on the basis of net weight of product in drums, and the determined by Test Method D2717 This test method measures specific gravities often are measured at temperatures other than the temperature gradient produced across the liquid by a known 15 °C The values of relative density (specific gravity) at 15 °C amount of energy introduced into the test cell by an electrically must be known to calculate the volume at 15 °C of the liquid heated platinum element delivered 13.4.2 The relative density (specific gravity) of a mineral 15.4 Significance and Use—A knowledge of thermal con- insulating liquid influences the heat transfer rates and may be ductivity is helpful in designing adequate heat transfer prop- pertinent in determining suitability for use in specific applica- erties for electrical apparatus A high value indicates a good tions In certain cold climates, ice may form in de-energized heat transfer efficiency property for the liquid electrical equipment exposed to temperatures below 0 °C, and the maximum specific gravity of the liquid used in such 16 Viscosity equipment should be at a value that will ensure that ice will not float in the liquid at any temperature the liquid might attain 16.1 Scope: 13.4.3 When making additions of insulating liquid to appa- 16.1.1 Test Method D445—This test method specifies a ratus in service, a difference in relative density (specific procedure for the determination of the kinematic viscosity of gravity) may indicate a tendency of the two bodies of liquid to liquid petroleum products, both transparent and opaque, by remain in separate layers rather than mixing into a homoge- measuring the time for a volume of liquid to flow under gravity through a calibrated glass capillary viscometer The dynamic viscosity can be obtained by multiplying the kinematic viscos- ity by the density of the liquid 6 D117 − 22 16.1.2 Practice D2161—Provides tables or equations for the 17.1.3 Test Method D1816—This test method covers the conversion of centistokes into Saybolt Universal Seconds or determination of the dielectric breakdown voltage of insulating Saybolt Furol Seconds at the same temperatures liquids (liquids of petroleum origin, silicone liquids, high fire-point mineral electrical insulating liquids, synthetic ester 16.2 Summary of Test Methods: liquids and natural ester liquids) This test method is applicable 16.2.1 Test Method D445—The time is measured in seconds to insulating liquids commonly used in cables, transformers, for a fixed volume of liquid to flow under gravity through the liquid-filled circuit breakers, and similar apparatus as an capillary of a calibrated viscometer under a reproducible insulating and cooling medium Refer to Terminology D2864 driving head and at a closely controlled temperature The for definitions used in this test method kinematic viscosity is the product of the measured flow time and the calibration constant of the viscometer 17.1.4 Test Method D3300—Applicable to any liquid com- 16.2.2 Practice D2161—The Saybolt Universal viscosity monly used as an insulating and cooling medium in high- equivalent to a given kinematic viscosity varies with the voltage apparatus subjected to impulse conditions, such as temperature at which the determination is made The basic transient voltage stresses arising from such causes as nearby conversion values are given in Table 1 of this practice for lightning strikes and high-voltage switching operations 37.8 °C (100 °F) Factors are given for converting units at other temperatures The Saybolt Furol viscosity equivalents are 17.2 Definition: given in Table 3 of this practice for 50.0 °C and 98.9 °C 17.2.1 dielectric breakdown voltage—the potential differ- (122 °F and 210 °F) only ence at which electrical failure occurs in an electrical insulating 16.2.3 Test Method D7042—This test method covers and material or insulation structure, under prescribed test condi- specifies a procedure for the concurrent measurement of both tions the dynamic viscosity, η, and the density, ρ, of liquid petroleum products and crude oils, both transparent and opaque The 17.3 Summary of Test Methods: kinematic viscosity, ν, can be obtained by dividing the dynamic 17.3.1 Test Method D877—The insulating liquid is tested in viscosity, η, by the density, ρ, obtained at the same test a test cup between two 25.4-mm (1-in.) diameter disk elec- temperature trodes spaced 2.54 mm (0.100 in.) apart A 60-Hz voltage is applied between the electrodes and raised from zero at a 16.3 Significance and Use: uniform rate of 3 kV/s The dielectric breakdown voltage is 16.3.1 The fundamental and preferred method for measur- recorded, prior to the occurrence of disruptive discharge, when ing kinematic viscosity is by use of Test Method D445 the voltage across the specimen has dropped to less than 100 V 16.3.2 Viscosity of electrical insulating liquids influences In the referee procedure, one breakdown test is made on each their heat transfer properties, and consequently the temperature of five fillings of the test cup, and the average and individual rise of energized electrical apparatus containing the liquid At values of breakdown voltage are reported low temperatures, the resulting higher viscosity influences the 17.3.2 Test Method D1816—The liquid is tested in a test cell speed of moving parts, such as those in power circuit breakers, between spherically capped (VDE) electrodes spaced either 1 switchgear, load tapchanger mechanisms, pumps, and regula- mm (0.040 in.) or 2 mm (0.080 in.) apart The liquid is stirred tors Viscosity controls insulating liquid processing conditions, before and during application of voltage by means of a such as dehydration, degassification and filtration, and liquid motor-driven stirrer A 60-Hz voltage is applied between the impregnation rates High viscosity may adversely affect the electrodes and raised from zero at a uniform rate of 0.5 kV/s starting up of apparatus in cold climates (for example, spare The voltage at which the current produced by breakdown of the transformers and replacements) Viscosity affects pressure liquid reaches the range of 2 to 20 mA, tripping a circuit drop, liquid flow, and cooling rates in circulating liquid breaker, is considered to be the dielectric breakdown voltage systems, such as in pipe-type cables and transformers In the procedure, five breakdown tests are made on one filling of the test cell If the five breakdowns fall within the statistical ELECTRICAL PROPERTIES requirements, the average value is reported If not, five additional breakdowns are required with the average of the ten 17 Dielectric Breakdown Voltage values reported 17.3.3 Test Method D3300—The electrode system consists 17.1 Scope: of either: (1) two 12.7-mm (0.5-in.) diameter spheres spaced 17.1.1 There are two standard test methods for determining 3.8 mm (0.15 in.) apart or (2) a 12.7-mm (0.5-in.) diameter the dielectric breakdown voltage of electrical insulating liquids sphere and a steel phonograph needle of 0.06-mm radius of at commercial power frequencies, D877 and D1816, and one curvature of point, spaced 25.4 mm (1.0 in.) apart The polarity standard test method for determining the dielectric breakdown of the needle with respect to the sphere can be either positive voltage of insulating liquids under impulse conditions, D3300 or negative The electrodes are immersed in the liquid in a test 17.1.2 Test Method D877—Applicable to petroleum liquids, cell An impulse wave of 1.2 by 50 µs wave shape (times to hydrocarbons, and askarels commonly used as insulating and reach crest value and to decay to half of crest value, respec- cooling media in cables, transformers, liquid-filled circuit tively) is applied at progressively higher voltages until break- breakers, and similar apparatus The suitability of Test Method down occurs D877 for testing liquids having viscosities exceeding 900 mm2/s at 40 °C (104 °F) has not been determined 17.4 Significance and Use: 17.4.1 Power Frequencies (Test Methods D877 and D1816)—The dielectric breakdown voltage of an insulating 7 D117 − 22 liquid at commercial power frequencies is of importance as a 18.1.1 Test Method D924 covers new electrical insulating measure of the liquid’s ability to withstand electric stress It is liquids as well as liquids in service or subsequent to service in the voltage at which breakdown occurs between two electrodes cables, transformers, liquid-filled circuit breakers, and other under prescribed test conditions It also serves to indicate the electrical apparatus presence of contaminating agents, such as water, dirt, moist cellulosic fibers, or conducting particles in the liquid, one or 18.1.2 This test method provides a procedure for making more of which may be present when low dielectric breakdown referee and routine tests at a commercial frequency of approxi- values are found by test However, a high dielectric breakdown mately 60 Hz voltage does not indicate the absence of all contaminants See Appendix X1 of either test method for other influences that 18.2 Summary of Test Method: affect the dielectric breakdown voltage of a liquid 18.2.1 The loss characteristic is commonly measured in terms of dissipation factor (tangent of the loss angle) or of 17.4.1.1 The ability of an insulating liquid to resist break- power factor (sine of the loss angle) For values up to 0.05, down under the test conditions is an indication of the ability of dissipation factor and power factor values are equal to each the insulating liquid to perform its insulating function in other within about one part in one thousand and the two terms electrical apparatus The average breakdown voltage is com- may be considered interchangeable monly used in specifications for the qualification and accep- 18.2.2 Test Method D924—The liquid test specimens are tance of insulating liquids It is also used as a control test for tested in a three-terminal or guarded electrode test cell main- the refining of new or reclaiming of used insulating liquids tained at the desired test temperature Using a bridge circuit, Because of the complex interactions of the factors affecting measure the loss characteristics and capacitance following the dielectric breakdown voltage the values obtained cannot be instructions appropriate to the bridge being used For routine used for design purposes tests, a two-electrode cell may be used 17.4.1.2 The square-edged disk electrodes of Test Method 18.3 Significance and Use: D877 are relatively insensitive to dissolved water in concen- 18.3.1 Dissipation Factor (or Power Factor)—This prop- trations below 60 % of the saturation level This method is erty is a measure of the dielectric losses in a liquid, and hence, recommended for acceptance tests on unprocessed insulating of the amount of energy dissipated as heat A low value of liquids received from vendors in tank cars, tank trucks, and dissipation factor (or power factor) indicates low dielectric drums It also may be used for the routine testing of liquids losses and a low level of soluble polar ionic or colloidal from selected power systems apparatus contaminants This characteristic may be useful as a means of quality control and as an indication of liquid changes in service 17.4.1.3 The more uniform electric field associated with resulting from contamination and liquid deterioration VDE electrodes employed in Test Method D1816 is more 18.3.2 Relative Permittivity (Dielectric Constant)— sensitive to the deleterious effects of moisture in solution, Insulating liquids are used in general either to insulate com- especially when cellulosic fibers are present in the liquid, than ponents of an electrical network from each other and from is the field in Test Method D877 Test Method D1816 can be ground, alone or in combination with solid insulating materials, used for processed or as received liquids Filtering and dehy- or to function as the dielectric of a capacitor For the first use, drating the liquid may increase Test Method D1816 dielectric a low value of relative permittivity is often desirable in order breakdown voltages substantially to have the capacitance be as small as possible, consistent with acceptable chemical and heat transfer properties However, an 17.4.2 Impulse Conditions (Test Method D3300): intermediate value of relative permittivity may sometimes be 17.4.2.1 This test method is most commonly performed advantageous in achieving a better voltage distribution be- using a negative polarity point opposing a grounded sphere tween the liquid and solid insulating materials with which the (NPS) The NPS breakdown voltage of fresh unused liquids liquid may be in series When used as the dielectric in a measured in the highly divergent field in this configuration capacitor, it is desirable to have a higher value of relative depends on liquid composition; decreasing with increasing permittivity so the physical size of the capacitor may be as concentration of aromatic, particularly polyaromatic, hydrocar- small as possible bon molecules 17.4.2.2 This test method may be used to evaluate the 19 Gassing Characteristics of Insulating Liquids Under continuity of composition of a liquid from shipment to ship- Thermal Stress at Low Temperature ment The NPS impulse breakdown voltage of a liquid can also be substantially lowered by contact with materials of 19.1 Scope: construction, by service aging, and by other impurities Test 19.1.1 Test Method D7150 describes the procedures to results lower than those expected for a given fresh liquid may determine the low temperature (120°C) gassing characteristics also indicate use or contamination of that liquid of insulating liquids specifically and without the influence of 17.4.2.3 Although polarity of the voltage wave has little or other electrical apparatus materials or electrical stresses This no effect on the breakdown strength of an liquid in uniform test method was primarily designed for insulating mineral fields, polarity does have a marked effect on the breakdown liquid It can be applied to other insulating liquids in which voltage of an liquid in nonuniform electric fields dissolved gas-in-liquid analysis (Test Method D3612) is com- monly performed 18 Dissipation Factor and Relative Permittivity 19.1.2 This test method is particularly suited for detection (Dielectric Constant) of the phenomenon sometimes known as “stray gassing” and is 18.1 Scope: 8 D117 − 22 also referred to in CIGRE TF11 B39 1.3 This test method is one that is sealed from the outside atmosphere Liquids sparged performed on electrical insulating liquids to determine the with air generally produce much more hydrogen as a percent- propensity of the liquid to produce certain gases such as age of the total combustible gas content as compared to liquids hydrogen and hydrocarbons at low temperatures sparged with nitrogen as these produce more hydrocarbons in relation to hydrogen 19.1.3 This test method details two procedures: 19.1.3.1 Method A describes the procedure for determining 20 Gassing Tendency the gassing characteristics of a new, unused insulating liquid, as received, at 120 °C for 164 h 20.1 Scope—Test Method D2300 describes a procedure to 19.1.3.2 Method B describes the procedure for processing measure the rate at which gas is evolved or absorbed by the insulating liquid through an attapulgite clay column to insulating liquids when subjected to electrical stress of suffi- remove organic contaminants and other reactive groups that cient intensity to cause ionization The liquid test specimen is may influence the gassing behavior of an insulating liquid, initially saturated with a selected gas (usually hydrogen) at which is suspected of being contaminated This procedure atmospheric pressure applies to both new and used insulating liquids 20.2 Summary of Test Method: 19.2 Summary of Test Method: 20.2.1 Test Method D2300—After being saturated with a 19.2.1 Method A—Insulating liquid is filtered through a gas (usually hydrogen) the liquid is subjected to a radial mixed cellulose ester filter A portion of the test specimen is electrical stress at a controlled temperature The gas space sparged for 30 min with dry air A test specimen is then placed above the liquid is ionized due to the electrical stresses; and into a glass syringe, capped and aged at 120 °C 6 2 °C for 164 therefore, the liquid surface at the liquid-gas interface is h The test is run in duplicate The other portion of the test subjected to ion bombardment The evolution or absorption of specimen is sparged for 30 min with dry nitrogen A test gas is measured with a gas burette and reported in µL/min specimen is then placed into a glass syringe, capped and aged at 120 °C 6 2 °C for 164 h The test is run in duplicate After, 20.3 Significance and Use—This test method indicates the test specimens have cooled, dissolved gas-in-liquid analy- whether insulating liquids are gas absorbing or gas evolving sis is then performed according to Test Method D3612 under the test conditions Numerical results obtained in differ- 19.2.2 Method B—Insulating liquid is passed through a ent laboratories may differ significantly in magnitude, and the heated (60 °C to 70 °C) attapulgite clay column at a rate of 3 results of this test method should be considered as qualitative mL to 5 mL per minute The insulating liquid is contacted with in nature the attapulgite clay at a ratio of 1 g clay to 33 mL (range: 30 mL to 35 mL) of insulating liquid (0.25 lb clay: 1 gal of 20.3.1 For certain applications when insulating liquid is insulating liquid) The insulating liquid is collected and sub- stressed at high voltage gradients, it is desirable to be able to jected to the testing as outlined in 19.2.1 determine the rate of gas evolution or gas absorption under specified test conditions At the present time, correlation of 19.3 Significance and Use: such test results with equipment performance is limited 19.3.1 Generation of combustible gases is used to determine the condition of liquid-filled electrical apparatus Many years 21 Resistivity of empirical evidence has yielded guidelines such as those given in IEEE C 57.104, IEC 60599 and IEC 61464 Industry 21.1 Scope: experience has shown that electric and thermal faulted in 21.1.1 Test Method D1169 covers the determination of liquid-filled electrical apparatus are the usual sources that specific resistance (resistivity) applied to new electrical insu- generate gases Experience has shown that some of the gases lating liquids, as well as to liquids in service, or subsequent to could form in the liquid at low temperatures or as a result of service, in cables, transformers, liquid-filled circuit breakers, contamination, without any other influences and other electrical apparatus 19.3.2 Some severely hydro-treated electrical equipment 21.1.2 This test method covers a procedure for making insulating liquids subjected to thermal stress and liquids that referee and routine tests with dc potential contain certain types of contamination may produce specific gases at lower temperatures than normally expected for their 21.2 Definition: generation and hence, falsely indicate abnormal operation of 21.2.1 specific resistance (resistivity)—of a liquid, the ratio the electrical apparatus Some new liquids have produced large of the dc potential gradient in volts per centimeter paralleling amounts of gases, especially hydrogen, without the influence of the current flow within the test specimen, to the current density other electrical apparatus materials or electrical stresses This in amperes per square centimeter at a given instant of time and renders interpretation of the dissolved gas analysis more under prescribed conditions This is numerically equal to the complicated resistance between opposite faces of a centimeter cube of a 19.3.3 Heating for 164 h has been found to be a sufficient liquid It is measured in ohm centimeters amount of time to reach a stable and characteristic gassing pattern 21.3 Summary of Test Method: 19.3.4 This method uses both dry air and dry nitrogen as the 21.3.1 Test Method D1169—The liquid test specimen is sparging gas This is to reflect either a electrical apparatus tested in three-terminal, or guarded-electrode test cell main- preservation system that allows oxygen to contact the liquid or tained at the desired test temperature A dc voltage is applied of such magnitude that the electric stress in the liquid is between 200 and 1200 V/mm The current flowing between the high- voltage and guarded measuring electrode is measured at the 9 D117 − 22 end of 1 min of electrification and the resistivity calculated intercept are calculated Using these two computed values, using specified equations appropriate to the method of mea- percentage of aromatic carbons, naphthenic carbons, and surement used A two-electrode cell may be used for routine paraffinic carbons are estimated from a correlation chart tests 23.3 Significance and Use—The primary purpose of this 21.4 Significance and Use—The resistivity of a liquid is a practice is to characterize the carbon-type composition of a measure of its electrical insulating properties under conditions liquid It is also applicable in observing the effect on liquid comparable to those of the test High resistivity reflects low constitution of various refining processes, such as solvent content of free ions and ion-forming particles and normally extraction, acid treatment, and so forth It has secondary indicates a low concentration of conductive contaminants application in relating the chemical nature of a liquid to other phenomena that have been demonstrated to be related to liquid CHEMICAL PROPERTIES composition 22 Acidity, Approximate 24 Compatibility with Construction Material 22.1 Scope—Test Method D1534 covers the determination 24.1 Scope—This test method covers screening for the of the approximate total acid value of used electrical insulating compatibility of materials of construction with electrical insu- liquids, in general, those having viscosities less than 24 mm2/s lating liquid for use in electrical equipment Solid materials at 40°C It is a simple procedure that can be applied in the field that can be tested for compatibility include varnishes, dip Where a quantitative neutralization value is required, use Test coatings, core steel, core steel coatings, gaskets, and wire Method D664 or D974 These test methods should be applied enamels in the laboratory 24.2 Summary of Test Method: 22.2 Summary of Test Method: 24.2.1 Test Methods D3455—The electrical insulating liquid 22.2.1 Test Method D1534—To determine whether the acid- and the material whose compatibility is being tested are aged ity is greater or less than a fixed arbitrary value, a fixed volume for 164 h at 100 °C Changes in the liquid and compatibility of liquid to be tested is added to the test bottle or graduated sample are observed and appropriate tests conducted cylinder, together with a small amount of indicator (phenol- phthalein) and the appropriate quantity of standard potassium 24.3 Significance and Use: hydroxide solution The mixture is shaken and allowed to 24.3.1 The magnitude of the change in the electrical prop- separate The color of the aqueous layer at the bottom of the erties of the insulating liquid is of importance in determining container when testing mineral liquids, or at the top when the contamination of the liquid by the test specimen testing askarels, determines whether the acidity is less than or 24.3.2 Physical and chemical changes in the liquid such as greater than the arbitrary value chosen color, interfacial tension, and acidity also indicate solubility or other adverse effects of the test specimen on the liquid 22.3 Significance and Use: 24.3.3 The physical changes of the test specimen, such as 22.3.1 The approximate acidity of used electrical insulating hardness, swelling, and discoloration, show the effect of the liquids is an estimate of the total acid value of the liquid As liquid on the test specimen and are used to determine the acid values increase, usually due to oxidation of the liquid in suitability of the material for use in insulating liquid service, the impairment of those liquid qualities, important to 24.3.4 A material meeting the criteria recommended does proper functioning of specific apparatus, increases In general, not necessarily indicate suitability for use in electrical equip- acidic by-products produce increased dielectric loss, increased ment Other properties must also be considered Additionally, corrosivity, and may cause thermal difficulties attributable to certain materials containing additives may meet the require- insoluble components called “sludge.” This test method is ments of this procedure, yet be unsatisfactory when subjected adapted to a specific volume of liquid; total acid values of 0.05 to longer term evaluations to 0.5 mg of potassium hydroxide per gram of liquid is a range which is functionally significant 25 Copper Content 23 Carbon-Type Composition 25.1 Scope: 25.1.1 Test Method D3635—Covers the determination of 23.1 Scope—This practice covers the determination of copper in new or used electrical insulating liquid For flame carbon-type composition of insulating liquids by correlation atomization, the lower limit of detectability is of the order of with basic physical properties Carbon-type composition is 0.1 mg/kg For nonflame atomization, the lower limit of expressed as percentage of aromatic carbons, percentage of detectability is less than 0.01 mg/kg naphthenic carbons, and percentage of paraffinic carbons Viscosity, relative density (or specific gravity), and refractive 25.2 Summary of Test Method: index are the only measurements required for use of this test 25.2.1 Test Method D3635—The test specimen of liquid is method filtered and diluted with an appropriate organic solvent and analyzed in an atomic absorption spectrophotometer Alterna- 23.2 Summary of Test Method: tive procedures are provided for instruments employing flame 23.2.1 Practice D2140—The viscosity, density and specific and nonflame atomization Concentration is determined by gravity, and refractive index of the liquid are measured From means of calibration curves prepared from standard samples these values, the viscosity-gravity constant and refractivity 10 D117 − 22 25.3 Significance and Use—Electrical insulating liquid may It can also be used to detect contamination such as from contain small amounts of dissolved metals derived either silicone liquids (via silicon) or from dirt (via silicon and directly from the base oil or from contact with metals during aluminum) refining or service When copper is present, it acts as a catalyst in promoting oxidation of the liquid This test method is useful 26.3.3 This test method can be used to indicate the effi- for research and to assess the condition of service-aged liquids ciency of reclaiming used insulating liquid 26 Elements in Insulating Oils by Inductively Coupled 27 Furanic Compounds in Electrical Insulating Liquids Plasma Atomic Emission Spectrometry (ICP-AES) 27.1 Scope—Test Method D5837 covers the determination, 26.1 Scope: in electrical insulating liquids, of the products of the degrada- 26.1.1 This test method describes the determination of tion of cellulosic materials such as paper, pressboard, and metals and contaminants in insulating liquids by inductively cotton material typically found as insulating materials in coupled plasma atomic emission spectrometry (ICP-AES) The electrical equipment These degradation products are substi- specific elements are listed in Table 1 of Test Method D7151 tuted furan derivatives, commonly referred to as furanic This test method is similar to Test Method D5185, but differs compounds or furans in methodology, which results in the greater sensitivity re- quired for insulating liquid applications 27.1.1 The commonly identified furans that may be identi- 26.1.2 This test method uses oil-soluble metals for calibra- fied by this method include: 5-hydroxymethyl-2-furaldehyde , tion and does not purport to quantitatively determine insoluble furfuryl alcohol, 2-furaldehyde , 2-acetylfuran, and 5-methyl- particulates Analytical results are particle size dependent, and 2-furaldehyde low results are obtained for particles larger than several micrometers 27.2 Summary of Test Method—Furanic compounds in elec- 26.1.3 This test method determines the dissolved metals trical insulating liquids are extracted from a known volume of (which may originate from overheating) and a portion of the test specimen by means of a liquid/liquid extraction or solid- particulate metals (which generally originate from a wear phase extraction A method for direct introduction of liquid into mechanism) While this ICP method detects nearly all particles the chromatograph is also described An aliquot of the extract less than several micrometers, the response of larger particles is introduced into a High Performance Liquid Chromatography decreases with increasing particle size because larger particles (HPLC) system equipped with a suitable analytical column and are less likely to make it through the nebulizer and into the UV detector Furanic compounds in the test specimen are sample excitation zone identified and quantified by comparison to standards of known 26.1.4 This test method includes an option for filtering the concentration liquid sample for those users who wish to separately determine dissolved metals and particulate metals (and hence, total 27.3 Significance and Use—Furanic compounds are gener- metals) ated by the degradation of cellulosic materials used in solid 26.1.5 Elements present at concentrations above the upper insulation systems of electrical equipment Furanic compounds limit of the calibration curves can be determined with which are liquid soluble to an appreciable degree will migrate additional, appropriate dilutions and with no degradation of into the insulating liquid High concentrations or unusual precision increases in the concentration of furanic compounds in liquid may indicate cellulose degradation from aging or incipient 26.2 Summary of Test Method: fault conditions 26.2.1 A weighed portion of a thoroughly homogenized insulating liquid is diluted 2.5:1 by weight with kerosine or 28 Dissolved Gas Analysis other suitable solvent Standards are prepared in the same manner An internal standard is added to the solutions to 28.1 Scope: compensate for variations in test specimen introduction effi- 28.1.1 This test method covers three procedures for the ciency The solutions are introduced to the ICP instrument by extraction and measurement of gases dissolved in electrical a peristaltic pump If free aspiration is used, an internal insulating liquid having a viscosity of 20 mm2/s or less at standard must be used By comparing emission intensities of 40 °C (104 °F), and the identification and determination of the elements in the test specimen with emission intensities mea- individual component gases extracted sured with the standards, the concentrations of elements in the 28.1.2 The individual component gases that may be identi- test specimen are calculated fied and determined include: hydrogen, oxygen, nitrogen, carbon monoxide, carbon dioxide, methane, ethane, ethylene, 26.3 Significance and Use: acetylene, propane, and propylene 26.3.1 This test method covers the rapid determination of 12 elements in insulating liquids, and it provides rapid screening 28.2 Summary of Test Methods: of used liquids for indications of wear Test times approximate 28.2.1 Method A (Test Method D3612)—Dissolved gases are several minutes per test specimen, and detectability is in the extracted from a sample of liquid by introduction of the liquid 10-100 µg/kg range sample into a pre-evacuated known volume The evolved gases 26.3.2 This test method can be used to monitor equipment are compressed to atmospheric pressure and the total volume condition and help to define when corrective action is needed measured 28.2.2 Method B (Test Method D3612)—Dissolved gases are extracted from a sample of liquid by sparging the liquid with the carrier gas on a stripper column containing a high surface area bead 11 D117 − 22 28.2.3 Method C (Test Method D3612) —The sample is reservoir, the pressure is returned to atmospheric, and the brought in contact with a gas phase in a sealed vial and the volume of the evolved gases is measured No correction is dissolved gases are allowed to equilibrate with the gas phase made for atmospheric pressure or ambient temperature The headspace above the liquid is sampled and analyzed The amount of dissolved gasses in the liquid is calculated from 29.4 Significance and Use: predetermined partition coefficients for each gas 29.4.1 Some types of electrical equipment require use of electrical insulating liquids of low gas content Capacitors and 28.2.4 There may be some differences in limits of detection certain types of electrical cable, particularly where used at high and precision and bias between Methods A, B, and C for the voltages, may suffer from the formation of gas bubbles with various gases consequent gaseous ionization if gas content is not sufficiently reduced In filling electrical apparatus, a low gas content 28.2.5 A portion of the extracted gases (Methods A and C) reduces foaming and also reduces available oxygen in sealed or all of the gases extracted (Method B) are introduced into a equipment, increasing the service life of the insulating liquid gas chromatograph equipped with suitable adsorption col- 29.4.2 These tests are not intended for use in purchase umn(s) The composition of the sample is calculated from its specifications because the liquid is customarily degassed im- chromatogram by comparing the area of the peak of each mediately before use These test methods can be used, component with the area of the peak of the same component on however, as a factory control test and a control and functional a reference chromatogram made on a standard mixture of test in installation and maintenance work by utilities These known composition tests require care in manipulation and the availability of trained, careful personnel 28.3 Significance and Use: 28.3.1 Liquid and liquid-immersed electrical insulating ma- 29.5 Precision: terials may decompose under the influence of thermal and 29.5.1 The precisions of two of the test methods are given in electrical stresses and in doing so generate gaseous decompo- the table below Refer to the original test methods for the sition products of varying composition, which dissolve in the conditions under which these precision values are applicable liquid The nature and amount of the individual component gases that may be recovered and analyzed may be indicative of Test Method Unit Repeatability Reproducibility the type and degree of the abnormality responsible for the gas D831 Gas Content % (if 0.1 %) ±0.02 generation The rate of gas generation and changes in concen- D1827 Gas Content % (0.1 to ±0.05 tration of specific gases over time are also used to evaluate the 15 %) condition of the electric apparatus 30 Neutralization (Acid and Base) Number 29 Gas Content of Cable and Capacitor Liquids 30.1 Scope: 29.1 Scope: 30.1.1 The two procedures available determine the acidic or 29.1.1 Test Method D831—Electrical insulating liquids of basic constituents in petroleum products Because the titration low and medium viscosities up to 190 mm2/s at 40 °C, end points of these methods differ, results may differ between including liquids used in capacitors and paper-insulated elec- the test methods tric cables and cable systems of the liquid-filled type 30.1.2 Test Method D664—Resolves the constituents into weak-acid and strong-acid components, provided the dissocia- 29.2 Definition: tion constants of the more highly ionized compounds are at 29.2.1 gas content of an liquid by volume—The total vol- least 1000 times that of the next weaker group Because the end ume of gases, corrected to 101 kPa (760 mm Hg) and 0 °C, point is determined potentiometrically, this test method is contained in a given volume of liquid, expressed as a percent- suitable for use with very dark samples age 30.1.3 Test Method D974—Applicable for the determination of acids or bases whose dissociation constants in water are 29.3 Summary of Test Methods: larger than 10−9 Constituents are classified as strong acid, 29.3.1 Test Method D831—The liquid is fed slowly into a weak acid, or strong base Excessively dark-colored liquids degassing chamber, located in an oven and initially evacuated cannot be tested by this test method due to obscuration of the to a pressure below 13 Pa (0.1 Torr) with a vacuum pump, so color indicator end point that the liquid is thoroughly exposed to the vacuum Condens- able gases are removed from the system by a cold trap The gas 30.2 Definitions: volume is calculated from the increase in pressure in the 30.2.1 total acid number—the number of milligrams of degassing chamber, measured by a McLeod gage KOH required to neutralize all acidic constituents present in 1 29.3.2 Test Method D1827—A small liquid sample is purged g of test specimen When neutralization number is specified of dissolved gases with pure carbon dioxide gas The gas without further qualification, total acid number is implied stream is then led into a gas burette containing a potassium 30.2.2 strong acid number—the number of milligrams of hydroxide solution The carbon dioxide and any other acidic KOH required to neutralize the strong acid constituents present gases are completely absorbed, and the volume of the remain- in 1 g of test specimen ing gas is measured 29.3.3 Test Method D2945—The liquid sample is allowed to 30.3 Summary of Test Methods: flow as a thin film into a chamber evacuated by the lowering of 30.3.1 Test Method D664—The test specimen is dissolved in a connecting mercury reservoir By raising the mercury a mixture of toluene and isopropyl alcohol containing a small amount of water and titrated potentiometrically with alcoholic 12 D117 − 22 potassium hydroxide or hydrochloric acid solution, using a 31.3 Significance and Use—The quantitative determination glass-indicating electrode and a calomel reference electrode of 2,6-ditertiary-butyl para-cresol or 2,6-ditertiary-butyl phe- The meter readings are plotted against the respective volumes nol measures the amount of this material that has been added of titrating solution, and the end points are taken at the to new electrical insulating liquid as protection against oxida- inflections in the resulting curve When no definite inflections tion or the amount remaining in a used liquid These test are obtained, end points are taken at meter readings corre- methods are also suitable for manufacturing control and for use sponding to those found for standard nonaqueous acidic and as specification acceptance tests basic buffer solutions 32 Oxidation Stability 30.3.2 Test Method D974—To determine the total acid or strong base number, the test specimen is dissolved in a mixture 32.1 Scope: of toluene and isopropyl alcohol containing a small amount of 32.1.1 Three oxidation test methods are applied to insulat- water, and the resulting single-phase solution is titrated at room ing liquid: temperature with standard alcoholic base or alcoholic acid 32.1.2 Test Method D1934—Covers two procedures for solution, respectively, to the end point indicated by the color subjecting electrical insulating liquids to oxidative aging: change of the added p-naphtholbenzein solution To determine Procedure A, without a metal catalyst, and Procedure B, with a the strong acid number, a separate portion of the sample is metal catalyst extracted with hot water, and the aqueous extract is titrated 32.1.2.1 This test method is applicable to liquids used as with potassium hydroxide solution, using methyl orange as an impregnating or pressure media in electrical power transmis- indicator sion cables as long as less than 10 % of the liquid evaporates during the aging procedures It applies and is generally useful 30.4 Significance and Use: primarily in the evaluation and quality control of unused 30.4.1 A low total acid content of an insulating liquid is liquids, either inhibited or uninhibited necessary to minimize electrical conduction and metal corro- 32.1.2.2 The precision statement for Test Method D1934 sion and to maximize the life of the insulation system should be the standard deviation of the logarithm of the 30.4.2 In used insulating liquids, an increase in total acid dissipation factor ratios rather than the coefficient of the number from the value of the unused product indicates variation of the ratios contamination by substances with which the liquid has been in 32.1.3 Test Method D2112—Is intended as a rapid method contact or a chemical change in the liquid from processes such for the evaluation of the oxidation stability of new mineral as oxidation An increase in total acid number may indicate the insulating liquids containing oxidation inhibitor This test is desirability of replacing used with fresh liquid, provided considered of value in checking the oxidation stability of new suitable rejection limits have been established and other tests mineral insulating liquids containing synthetic oxidation in- confirm the need for the change hibitor in order to control the continuity of this property from shipment to shipment The applicability of this procedure for 31 Oxidation Inhibitor Content use with inhibited insulating liquids of more than 12 mm2/s at 40°C has not been established 31.1 Scope: 32.1.4 Test Method D2440—Covers the evaluation of the 31.1.1 These test methods cover the determination of the acid- and sludge-forming tendency of new mineral transformer weight percent of 2.6–ditertiary-butyl paracresol (DBPC, insulating liquids It is considered of value in studying the acid- BHT) and 2,6-ditertiary-butyl phenol (DBP) in new or used and sludge-forming propensity of a new grade of mineral electrical insulating liquid in concentrations up to 0.5 % Two transformer insulating liquid before commercial application test methods are available for the determination of the com- monly used inhibitors 32.2 Summary of Test Methods: 31.1.2 Test Method D2668—Determines the concentration 32.2.1 Test Method D1934—This test method consists of of either inhibitor, or their mixtures, in concentrations up to 0.5 exposing for 96 h 300 mL of liquid in a 400 mL beaker to mass %, by measuring the infrared absorbance of the liquid at moving air in an oven controlled at 115 °C, with or without 15 selected frequencies cm2 of metal catalyst Changes in such properties as color, total 31.1.3 Test Method D4768—This test measures the concen- acid number, power factor, and resistivity of the aged liquid tration of either inhibitors or their mixtures, in concentrations can be used to determine the oxidative deterioration of the up to 0.5 % mass, by gas chromatographic separation and liquid quantitation to a suitable standard 32.2.2 Test Method D2112—The test specimen is agitated by rotating axially at 100 rpm at an angle of 30° from the 31.2 Summary of Test Methods: horizontal under an initial oxygen pressure of 620 kPa (90 psi) 31.2.1 Test Method D2668—The infrared absorbance of the in a pressure vessel with a glass sample container and copper test specimen is measured at the frequencies appropriate to catalyst coil, in the presence of water, at a bath temperature of 2,6-ditertiary-butyl para-cresol and 2,6-ditertiary-butyl phenol 140 °C The time for an liquid to react with a given volume of and the concentrations calculated from a calibration curve oxygen is measured; completion of the test is indicated by a 31.2.2 Test Method D4768—A column clean-up is em- 172 kPa (25 psi) drop in pressure ployed to remove interfering substances, followed by a gas 32.2.3 Test Method D2440—The test liquid is charged to a chromatographic separation and concentration measured by glass oxidation tube containing copper wire catalyst The tube comparison to suitable standards 13 D117 − 22 is placed in a oil bath at 110 °C, and oxygen is bubbled through 34.1.1 Unused and in-service insulating liquids may contain separate liquid samples for 72 and 164 h The n-heptane elemental sulfur or sulfur compounds, or both, that cause insoluble sludge and total acid number of the aged liquid is corrosion under certain conditions of use This test method is measured to determine the extent of oxidation designed to detect the presence of, or the propensity to form, free (elemental) sulfur and corrosive sulfur compounds by 32.3 Significance and Use: subjecting copper or silver to contact with an insulating liquid 32.3.1 The development of liquid sludge and acidity result- under prescribed conditions ing from oxidation during storage, processing, and long service life should be held to a minimum This minimizes electrical 34.2 Summary of Test Method: conduction and metal corrosion, maximizes insulation system 34.2.1 Test Method D1275: life and electrical breakdown strength, and ensures satisfactory 34.2.1.1 Copper Corrosion—220 mL of insulating liquid is heat transfer aged in a sealed heavy walled bottle for 48 h at 150°C in the 32.3.2 The oxidation stability tests described in Section 32 presence of a copper strip may be used to evaluate the tendency to form sludge or acids 34.2.1.2 Silver Corrosion—220 mL of insulating liquid is under oxidizing conditions, to ensure the continuity of quality aged in a sealed heavy walled bottle for 48 h at 150°C in the of mineral insulating liquid shipments, and for specification presence of a silver strip purposes A low tendency to form sludge and acid in laboratory tests is desirable, although the liquid showing the least dete- 34.3 Significance and Use—In most of their uses, insulating rioration in the laboratory is not necessarily the best in service liquids are continually in contact with metals that are subject to 32.3.3 The oxidation stability Test Methods D2112 and corrosion The presence of elemental sulfur or corrosive sulfur D2440 are used in the Specifications D3487 and D5222 for compounds will result in deterioration of these metals and insulating liquids cause conductive or high resistive films to form The extent of deterioration is dependent upon the quantity and type of 33 Polychlorinated Biphenyl Content (PCB) corrosive agent and time and temperature factors Detection of these undesirable impurities, even though not in terms of 33.1 Scope: quantitative values, is a means for recognizing the hazard 33.1.1 Test Method D4059—Describes a quantitative tech- involved nique for determining the concentration of polychlorinated biphenyls (PCBs) in electrical insulating liquids by gas chro- 34.3.1 Two methods are provided, one for copper and one matography for silver corrosion Copper is slightly less sensitive to sulfur corrosion than silver but the results are easier to interpret and 33.2 Definition: less prone to error The silver corrosion procedure is provided 33.2.1 PCB concentration—is normally expressed in units especially for those users who have applications where the of parts per million (ppm) on a weight by weight basis, insulating liquid is in contact with silver surface specifically in mg/kg Standard chromatograms of Aroclors 5 1242, 1254, and 1260 are used to determine the concentration 35 Water Content of PCB in the sample 35.1 Scope—Test Method D1533 covers the determination 33.3 Summary of Test Method—Following dilution of the of water present in insulating liquids, in concentrations most test specimen in a suitable solvent, the solution is treated to commonly below 200 ppm remove interfering substances A small portion is then injected into a gas chromatographic column where the components are 35.2 Summary of Test Method: separated and their presence measured by an electron capture 35.2.1 This test method is based on the reduction of iodine or halogen-specific electrolytic conductivity detector The test in accordance with the traditional Karl Fischer reaction method is made quantitative by comparing the response of a 35.2.2 Test Method D1533 electrochemically generates the sample to that of a known quantity of one or more standard iodine required for Karl Fischer titration Aroclors obtained under the same conditions 35.2.3 This automatic coulometric titration procedure re- quires the use of an instrument that is designed and calibrated 33.4 Significance and Use—National, state and local regu- to deliver a known electrical current which generates sufficient lations require that electrical apparatus and electrical insulating iodine to neutralize a known weight of water per minute The liquids containing PCB be handled and disposed of through the two-part titration solution is first brought to near a zero dryness use of specific procedures as determined by the PCB content of by iodine produced by the generator when the controls are the insulating liquid The results of this test method can be placed in the “standby” setting The test specimen is added; and useful in selecting appropriate handling and disposal proce- the titration begun, allowing the test specimen to be automati- dures cally titrated by producing iodine at the generator anode until the equivalent point is reached and the titration is complete 34 Sulfur, Corrosive Water content is read directly on the meter in micrograms (or parts per million) 34.1 Scope—This test method covers the detection of cor- rosive sulfur compounds (both organic and inorganic) in 35.3 Significance and Use—A low water content of insulat- electrical insulating liquids ing liquid is necessary to achieve adequate electrical strength and low dielectric loss characteristics, to maximize the insula- 5 Registered trademark of Monsanto Co tion system life, and to minimize metal corrosion Water in 14 D117 − 22 solution cannot be detected visually and must be determined by application The material described in this specification may other means This test shows the presence of water that may not not be miscible with electrical insulating liquids of non- be evident from electrical tests petroleum origin The user should contact the manufacturer of the high fire point insulating liquid for guidance in this respect SPECIFICATIONS 37.1.4 This specification applies only to new insulating 36 Mineral Insulating Liquid for Electrical Apparatus material, liquid as received prior to any processing Informa- tion on in-service maintenance testing is available in appropri- 36.1 Scope: ate guides The user should contact the manufacturer of the 36.1.1 Specification D3487—The physical, chemical, and equipment if questions of recommended characteristics or electrical properties of two types of unused mineral insulating maintenance procedures arise liquid of petroleum origin for use as an insulating and cooling medium in new and existing power and distribution electrical 38 Silicone Fluid used for Electrical Insulation apparatus, such as transformers, regulators, reactors, liquid- filled circuit breakers, switchgear, and attendant equipment are 38.1 Scope: given in this specification 38.1.1 Specification D4652 covers silicone fluid for use in 36.1.2 Type I liquid has a maximum oxidation inhibitor transformers, capacitors, and electronic assemblies as an insu- content of 0.08 mass % and Type II liquid a maximum of 0.3 lating or cooling medium, or both mass % Except for the inhibitor content and oxidation stability 38.1.2 Silicone fluid covered by this specification is poly- requirements, the two liquids have similar performance prop- dimethylsiloxane having a normal viscosity of 50 cSt at 25 °C erties and a fire point of 340 °C or greater This specification applies 36.1.3 Specification D3487 is intended to define a mineral only to new silicone fluid Information on in-service mainte- insulating liquid that is functionally interchangeable with nance testing is available in appropriate guides existing liquids, is compatible with existing apparatus and with appropriate field maintenance, and will satisfactorily maintain 39 Natural (Vegetable Oil) Ester Fluids used in its functional characteristics in its application in electrical Electrical Apparatus equipment This specification applies only to new insulating liquid prior to introduction into apparatus 39.1 Scope: 39.1.1 Specification D6871 covers a less flammable natural 37 Less Flammable Electrical Insulating Liquids vegetable ester insulating liquid for use as a dielectric and cooling medium in new and existing power and distribution 37.1 Scope: electrical apparatus such as transformers and attendant equip- 37.1.1 Specification D5222 describes a less flammable min- ment eral based insulating liquid, for use as a dielectric and cooling 39.1.2 This specification is intended to define a natural medium in new and existing power and distribution electrical vegetable ester electrical insulating liquid that is compatible apparatus, such as transformers and switchgear with typical materials of construction of existing apparatus and 37.1.2 Less flammable insulating liquid differs from con- will satisfactorily maintain its functional characteristic in this ventional mineral insulating liquid by possessing a fire-point of application The material described in this specification may at least 300 °C This property is necessary in order to comply not be miscible with some synthetic electrical insulating with certain application requirements of the National Electric liquids The user should contact the manufacturer of the natural Code (Article 450-23) or other agencies The material dis- ester insulating liquid for guidance in this respect cussed in this specification is miscible with other petroleum 39.1.3 This specification applies only to new insulating based insulating liquids Mixing high fire-point liquids with liquid as received prior to any processing The user should lower fire-point hydrocarbons insulating liquids (for example, contact the manufacturer of the equipment or liquid if ques- Specification D3487 mineral liquid) may result in fire points tions of recommended characteristics or maintenance proce- less the 300 °C dures arise 37.1.3 This specification is intended to define a less flam- mable electrical mineral insulating liquid that is compatible 40 Keywords with typical material of construction of existing apparatus and will satisfactorily maintain its functional characteristic in its 40.1 chemical properties; electrical insulating liquids; elec- trical properties; measured; physical properties; properties; sampling; specification 15 D117 − 22 ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters Your comments will receive careful consideration at a 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