1、Designation: D2300 08 (Reapproved 2017)Standard Test Method forGassing of Electrical Insulating Liquids Under ElectricalStress and Ionization (Modified Pirelli Method)1This standard is issued under the fixed designation D2300; the number immediately following the designation indicates the year ofori
2、ginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method measures the rate at which gas isevolved or a
3、bsorbed by insulating liquids when subjected toelectrical stress of sufficient intensity to cause ionization incells having specific geometries.1.2 This test method is not concerned with bubbles arisingfrom supersaturation of the insulating liquid.1.3 This standard does not purport to address all of
4、 thesafety concerns, if any, associated with its use. It is theresponsibility of whoever uses this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.For specific precautions see 5.1.4 and 8.4.2. Referenced
5、 Documents2.1 ASTM Standards:2D924 Test Method for Dissipation Factor (or Power Factor)and Relative Permittivity (Dielectric Constant) of Electri-cal Insulating Liquids3. Summary of Test Method33.1 After being saturated with a gas (usually hydrogen), theinsulating liquid is subjected to a radial ele
6、ctrical stress. Thegas space above the insulating liquid film is ionized due to theelectrical stresses and therefore the insulating liquid surface atthe insulating liquid-gas interface is subjected to ionic bom-bardment. The evolving or absorbing of gas is calculated involume per unit of time from c
7、hanges in pressure with timefrom two specimens run on the same sample.3.2 This test method indicates whether insulating liquids aregas absorbing or gas evolving under the test conditions.4. Significance and Use4.1 For certain applications when insulating liquid isstressed at high voltage gradients,
8、it is desirable to be able todetermine the rate of gas evolution or gas absorption underspecified test conditions. At present time correlation of suchtest results with equipment performance is limited.4.2 In this test method, hydrogen (along with low molecularweight hydrocarbons) is generated by ion
9、ic bombardment ofsome insulating liquid molecules and absorbed by chemicalreaction with other insulating liquid molecules. The valuereported is the net effect of these two competing reactions. Thearomatic molecules or unsaturated portions of molecules pres-ent in insulating liquids are largely respo
10、nsible for thehydrogen-absorbing reactions. Both molecule type, as well asconcentration, affects the gassing tendency result. Saturatedmolecules tend to be gas evolving. The relation betweenaromaticity and quantity of unsaturates of the insulating liquidand gassing tendency is an indirect one and ca
11、nnot be used fora quantitative assessment of either in the insulating liquid.4.3 This test method measures the tendency of insulatingliquids to absorb or evolve gas under conditions of electricalstress and ionization based on the reaction with hydrogen, thepredominant gas in the partial discharge. F
12、or the testconditions, the activating gas hydrogen, in contrast to othergases, for example, nitrogen, enhances the discrimination ofdifferences in the absorption-evolution patterns exhibited bythe insulating liquids. Insulating liquids shown to have gas-absorbing (H2) characteristics in the test hav
13、e been used toadvantage in reducing equipment failures, particularly cablesand capacitors. However, the advantage of such insulatingliquids in transformers is not well defined and there has beenno quantitative relationship established between the gassingtendency as indicated by this test method and
14、the operatingperformance of the equipment. This test method is not con-cerned with bubble evolution, which may arise from physicalprocesses associated with super-saturation of gases in oil orwater vapor bubbles evolving from wet insulation.1This test method is under the jurisdiction of ASTM Committe
15、e D27 onElectrical Insulating Liquids and Gasesand is the direct responsibility of Subcom-mittee D27.05 on Electrical Test.Current edition approved Jan. 1, 2017. Published February 2017. Originallyapproved in 1968. Last previous edition approved in 2008 as D2300 - 08. DOI:10.1520/D2300-08R17.2For re
16、ferenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The original Pirelli method is described by Guiseppe Palandri and U
17、goPellagatti in the paper. “Gli Oli Isolanti per Cavi Elettrici” (Insulating Oils forElectric Cables), Elettrotecnica (Milan) Jan. 8, 1955. Translation of this paper iscontained in “Minutes of the Meeting of the Insulated Conductors Committee of theAmerican Institute of Electrical Engineers,” Nov. 1
18、5 and 16, 1955.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevel
19、opment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15. Apparatus5.1 The apparatus for making gassing tests where theinsulating liquid is saturated in the same cell that is usedthereafter to electrically str
20、ess the insulating liquid is shown inFig. 1. The apparatus consists of the following:5.1.1 Gassing Cell and Buret Assembly , as shown in Fig. 1,with dimensions as given in Fig. 2. The gassing cell consists ofthe following two components:5.1.1.1 Cell made of borosilicate glass with the part understre
21、ss constructed of 16 mm inside diameter and 18 mm outsidediameter truebore tubing. This cell has an outer (ground)electrode of painted or plated silver with a vertical slit forobserving the insulating liquid level, and a metal conductorband for ground connection.5.1.1.2 Hollow High-Voltage Electrode
22、 made of 10 60.1-mm outside diameter center-less-ground and polished No.304 stainless steel seamless tubing and containing an 18-gagestainless steel capillary tubing as a gas passage. The electrodeshall be supported and centered by a precision-machined 24/40recessed TFE-fluorocarbon plug.A18-in. nee
23、dle valve (E) withgas inlet is on top of the electrode.5.1.2 Gas Buret (Fig. 1) made of 7-mm outside diameterborosilicate glass tubing with an etched scale, tapered glassjoint (G) for connecting to the gassing cell, a bypass stopcock(D), and three glass bulbs, (A, B, and C).5.1.3 Oil Bath with therm
24、ostatic control to maintain the bathat test temperature 60.5C. The bath shall be equipped with astirrer, a heating arrangement capable of maintaining thenecessary temperature control, a suitable support for thegassing test cell assembly, and a thermometer graduated in0.1C divisions. As the test is t
25、emperature sensitive, it isimportant that the calibration is traceable to a standard, such asNIST.5.1.4 Transparent Safety Shield to protect the operator fromcontact with high voltage.5.1.5 High-Voltage Transformer, providing a test voltagehaving a frequency in the range of 45 to 65 Hz. Thetransform
26、er and its controlling equipment shall be of such sizeand design that with the test specimen in the circuit, the voltagewave shape shall approximate a sinoid with both half cyclesclosely alike. The ratio of peak-to-rms values should be equalto the square root of two within 65 % while maintaining 10R
27、V 62%.6. Reagents and Materials6.1 Hydrogen, oxygen-free. See Note 1.6.2 Dibutyl Phthalate, reagent grade.6.3 2-Propanol, reagent grade.6.4 Low vapor pressure grease, such as high vacuumsilicone grease.6.5 Unless otherwise indicated, it is intended that all re-agents shall conform to the Committee o
28、n Analytical Reagentsof the American Chemical Society.NOTE 1Hydrogen normally is the saturating gas but other gases, suchas nitrogen, carbon dioxide, argon, or air may be used.7. Preparation of Apparatus7.1 Clean the glass cell by first rinsing it inside and outsidewith a suitable hydrocarbon solven
29、t such as heptane or othersolvent suitable for the dielectric liquid test tested. Then fill thecell with the hydrocarbon solvent and scrub to remove waxydeposits from previous tests. Clean the tapered joint, takingcare that none of the grease enters the cell. Again rinse withhydrocarbon solvent and
30、blow dry with clean compressed air.Check the silver electrode and repair if necessary.7.2 Clean the hollow electrode by blowing a suitable hy-drocarbon solvent through the capillary tube with compressedair, rinsing the insulating liquid off the entire electrode with asuitable hydrocarbon solvent, su
31、ch as heptane, and wiping offany waxy deposit with tissue paper. Polish the surface with a2-propanol soaked towel. If there are visible marks on thestainless steel shaft of the electrode, they should be polishedwith a suitable device, such as a buffing wheel, wiping off theFIG. 1 Schematic Diagram o
32、f Cell and Manometer AssemblyFIG. 2 Detailed Dimensions of the Glass Cell and the Inner(High-Voltage) ElectrodeD2300 08 (2017)2buffing compound carefully with tissue paper moistened with asuitable hydrocarbon solvent such as heptane.7.3 Apply a light coat of low vapor pressure silicone greaseto the
33、stopcock (D) and the standard-taper joint (G) andassemble the glass cell and buret, but do not insert the electrodeinto the glass cell.7.3.1 Caution: Do not allow silicone grease to contaminatethe inside of the buret, gassing cell, electrode, or oil.7.4 Fill the buret to the half-full mark with dibu
34、tyl phthalate.8. Procedure8.1 Introduce 5 6 0.1 mL of the insulating liquid sampleinto the glass cell by means of a hypodermic syringe.8.2 Lightly coat the TFE-fluorocarbon plug of the electrodewith the test insulating liquid or low vapor pressure siliconegrease and insert the electrode into the gla
35、ss cell.NOTE 2It has been found helpful to place a few drops of the testinsulating liquid on top of the TFE-fluorocarbon plug to act as a gas-seal.If there is a leak, use of the oil may help detect it through the appearanceof gas bubbles at the top of the Teflon plug.8.3 Bring the oil bath up to 80C
36、 (for some applications itmay be desirable to use 60C; in either case, report testtemperature as indicated in 10.1.1). Suspend the gassing celland buret assembly in the oil bath at the level indicated in Fig.1, and connect the lead from the outside electrode to ground.8.4 Attach the gas inlet and ou
37、tlet connections. When usinghydrogen, the gas outlet should lead outside the building, eitherdirectly or through a fume hood.8.5 Close the stopcock (D) and open the valve (E) to allowthe saturating gas to bubble through the test insulating liquidand the buret liquid at a steady rate (about 3 bubbles
38、/s) for 10min.8.6 Open the stopcock (D) and continue bubbling thesaturating gas through the test insulating liquid for an addi-tional 5 min.8.7 After a total of 15 min of gas bubbling, close the firstvalve (E) and then the stopcock (D), making certain the liquidlevels in the two legs of the buret ar
39、e equal.8.8 Connect the high-voltage lead to the center electrode.8.9 Place the transparent safety shield in position and takethe buret reading after checking the bath temperature.NOTE 3To facilitate reading the buret, it has been found helpful toilluminate the buret scale and to use a magnifying gl
40、ass or a small opticalmagnifying device.8.10 Turn on the high voltage and adjust to 10 kV. Recordthe time and voltage, as well as the buret level, and check theobservation slit on the outer electrode for onset of the gassingreaction.8.11 After 10 min, record the buret level, voltage, and bathtempera
41、ture.8.12 After an additional 50 min, again record the buretlevel, voltage, and bath temperature, and turn off the voltage.8.13 To ensure the equipment is operating correctly it isrecommended that the buret level be read every 10 min untilthe test is terminated.Aplot of the readings versus time shou
42、ldgive a reasonably straight line. If the data are widely scattered,the equipment should be checked and the test rerun.8.14 For oils with very low gassing tendencies, it may benecessary to stop the test to vent the manometer. The total gasabsorbed is the sum of the gas absorbed before and afterventi
43、ng.8.15 Repeat the procedure on a fresh test specimen, 8.1 8.13.9. Calculation9.1 Calculate the gassing tendency as follows:G 5B602 B10!K/Twhere:G = gassing tendency, L/min,B60= buret reading, mm, at 60 min of test,B10= buret reading, mm, at 10 min of test,K = buret constant = Lmm buret reading, (se
44、e AppendixX2) andT = test time of computed gassing rate, min = 60 10 = 50min.NOTE 4This will result in an answer which will be positive ( + ) if gasis evolved, and negative () if gas is absorbed.9.2 Take the average of the two values of G. If the averagevalues are different by more than 0.3 + 0.26 |
45、X|, then the testshould be repeated. Where |X| is the absolute value of duplicatedeterminations in microliters per minute. Duplicate analysesare performed because it is difficult to detect when a problemoccurs during a test. The equation to determine when duplicateanalysis are acceptable is based on
46、 general experiences and isnot derived from a round-robin program for this test method.9.3 See Appendix X1 to determine the electrical stress forthe electrode system and dielectric liquids.10. Report10.1 Report the following:10.1.1 Test temperature,10.1.2 Test voltage and frequency,10.1.3 Saturating
47、 gas,10.1.4 Test period, and10.1.5 Average gassing rate in microlitres per minute.11. Precision and Bias11.1 The precision of this test method is based on aninterlaboratory study of D2300-01, Standard Test Methods forGassing of Electrical Insulating Liquids Under Electrical Stressand Ionization (Mod
48、ified Pirelli Method), conducted in 2006.One laboratory tested two different materials. Every “testresult” represents the average of two determinations. Thelaboratory obtained ten replicate test results for each material.4See Table 1.11.1.1 ReapeatabilityTwo test results obtained within onelaborator
49、y shall be judged not equivalent if they differ by more4Supporting data are available from ASTM International Headquarters. RequestRR:D27-1019.D2300 08 (2017)3than the “r” value for that material; “r” is the intervalrepresenting the critical difference between two test results forthe same material, obtained by the same operator using thesame equipment on the same day in the same laboratory.11.1.2 ReproducibilityTwo test results shall be judged notequivalent if they differ by more than the “R” value for thatmaterial; “R” is the interval representing the difference
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