1、Designation: D7150 05D7150 13Standard Test Method for theDetermination of Gassing Characteristics of InsulatingLiquids Under Thermal Stress at Low Temperature1This standard is issued under the fixed designation D7150; the number immediately following the designation indicates the year oforiginal ado
2、ption 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 describes the procedures to determine the low temperat
3、ure (120C) gassing characteristics gassingcharacteristics due to thermal stress at 120C of insulating liquids specifically and without the influence of other electricalapparatus materials or electrical stresses. This test method was primarily designed for insulating mineral oil. It can be applied to
4、other insulating liquids in which dissolved gas-in-oil analysis (Test Method D3612) is commonly performed.1.2 This test method is particularly suited for detection of the phenomenon sometimes known as “stray gassing” and is alsoreferred to in CIGRE TF11 B39.1.3 This test method is performed on trans
5、former insulating liquids to determine the propensity of the oil to produce certaingases such as hydrogen and hydrocarbons at low temperatures.1.4 This test method details two procedures:1.5 MethodAdescribes the procedure for determining the gassing characteristics of a new, unused insulating liquid
6、, as received,insulating liquids, at 120C for 164 h.1.6 Method B describes the procedure for processing the insulating liquid through an attapulgite clay column to remove organiccontaminants and other reactive groups that may influence the gassing behavior of an insulating liquid, which is suspected
7、 of beingcontaminated. This procedure applies to both new and used insulating liquids.1.7 The values stated in SI units are to be regarded as standard. English units are used when there is no metric equivalent.1.8 This standard does not purport to address all of the safety concerns, if any, associat
8、ed with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1933 Specification for Nitrogen Gas as an Electrical Insulat
9、ing MaterialD3612 Test Method for Analysis of Gases Dissolved in Electrical Insulating Oil by Gas ChromatographyD3613 Practice for Sampling Insulating Liquids for Gas Analysis and Determination of Water Content (Withdrawn 2007)32.2 IEEE Document:3C 57.104 IEEE Guide for the Interpretation of Gases G
10、enerated in Oil-Immersed Transformers, 199120082.3 IEC Documents:4IEC 60599 Mineral oil-impregnated electrical equipment in service Guide to the interpretation of dissolved and free gasesanalysis, 19992007IEC 61464 Guide for the interpretation of dissolved gas analysis (DGA) in bushings where oil is
11、 the impregnating medium ofthe main insulation (generally paper), 1998CIGRE TF11 B39 Gas formation tendency test for mineral transformer oils, 2002.20021 This test method is under the jurisdiction of ASTM Committee D27 on Electrical Insulating Liquids and Gases and is the direct responsibility of Su
12、bcommittee D27.03on Analytical Tests.Current edition approved May 1, 2005Dec. 1, 2013. Published June 2005January 2014. Originally approved in 2005. Last previous edition approved in 2005 as D7150-05.DOI: 10.1520/D7150-05.10.1520/D7150-13.2 For referencedASTM standards, visit theASTM website, www.as
13、tm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from the Institute of Electrical and Electronic Engineers, Inc, (IEEE), 445 Hoes Lane, Piscataway, NJ 08854; w
14、ww.ieee.org4 Available from the International Electrotechnical Commission, 3, rue de Varemb, P.O. Box 131 CH-1211, Geneva 20, Switzerland; www.iec.chThis document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the
15、previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright AST
16、M International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions:3.1.1 stray gassing, nthe production of gases in an insulating liquid due to heating, contamination or in combination.3.1.2 attapulgite clay,Fullers Earth, nalso termed
17、Fullers Earth. Highly highly adsorbent clay-like substance consistingmainly of hydrated aluminum silicates.silicates with the main minerals being montmorillonite, kaolinite, attapulgite andpalygorskite.4. Summary of Test Method4.1 Method AInsulating liquid is filtered through a mixed cellulose ester
18、 filter. A portion of the test specimen is sparged for30 min with dry air. A test specimen is then placed into a glass syringe, capped and aged at 120 6 2C for 164 h. The test is runin duplicate. The other portion of the test specimen is sparged for 30 min with dry nitrogen. A test specimen is then
19、placed intoa glass syringe, capped and aged at 120C 6 2C for 164 h. The test is run in duplicate.After,After the test specimens have cooled,dissolved gas-in-oil analysis is then performed according to Test Method D3612. or IEC Method 60599.4.2 Method BInsulating oil is passed through a heated (60 to
20、 70C) attapulgite clayFullers earth column at a rate of 3 to 5mL per minute. The insulating liquid is contacted with the attapulgite clayFullers earth at a ratio of 1 g clay to 33 mL (range: 30to 35 mL) of insulating liquid (0.25 lb clay: 1 gal of insulating liquid). liquid. The insulating liquid is
21、 collected and subjected tothe testing as outlined in 4.1.5. Significance and Use5.1 Generation of combustible gases is used to determine the condition of oil-filled electrical apparatus. Many years of empiricalevidence has yielded guidelines such as those given in IEEE C57.104, IEC 60599 and IEC 61
22、464. Industry experience has shownthat electric and thermal faultedfaults in oil-filled electrical apparatus are the usual sources that generate gases. Experience hasshown that some of the gases could form in the oil at low temperatures due to thermal stress or as a result of contamination, withouta
23、ny other influences.5.2 Some severely hydro-treated transformer oils subjected to thermal stress and oils that contain certain types of contaminationmay produce specific gases at lower temperatures than normally expected for their generation and hence, falsely indicate abnormaloperation of the elect
24、rical apparatus. Some new oils have produced large amounts of gases, especially hydrogen, without theinfluence of other electrical apparatus materials or electrical stresses. This renders interpretation of the dissolved gas analysis morecomplicated.5.3 Heating for 164 h has been found to be a suffic
25、ient amount of time sufficient to reach a stable and characteristic gassingpattern.5.4 This method uses both dry air and dry nitrogen as the sparging gas. This is to reflect either aan electrical apparatuspreservation system that allows oxygen to contact the oil or one that is sealed from the outsid
26、e atmosphere. Oils sparged with airgenerally produce much more hydrogen as a percentage of the total combustible gas content as compared to oils sparged withnitrogen as these produce more hydrocarbons in relation to hydrogen.6. Reagents and Materials6.1 Mixed Cellulose Ester Membrane Filter, consist
27、ing of either 1 or 1.2 m pore size, of correct diameter to fit in the filteringapparatus listed in 6.2.6.2 Vacuum Filtering Apparatus , Apparatus, consisting of funnel reservoir (250 mL or larger), clamp, base, stopper andreceiving flask. The 47 mm size is the type most often used.6.3 Dry Nitrogen,
28、meeting the requirements of Specification D1933, Type III with the following exception: the totalhydrocarbon content must be 0.5 ppm.L/L. This type of gas is sometimes referred to as Ultra-High Purity (UHP).6.4 Dry Air, meeting the following requirements: 20 to 22 % oxygen, 3 ppmL/L water, and 1 ppm
29、L/L total hydrocarbons.This type of gas is sometimes referred to as Zero Grade.6.5 Ovens, forced-draft, adjustable to 120 6 2C and a drying oven, convection or forced-draft, or both, adjustable to 100 65C.6.6 Syringes, glass, either 30 or 50 mL, either matched plunger and barrel or precision ground
30、to 0.006 6 0.001 mm maximumspacing between the inside of the barrel to the outside of the plunger for both the 30 mL and 50 mL syringes.6.7 Female-Luer-to-Closed-End-Adapter , nickel-plated brass.6.8 Attapulgite Clay (Fullers Earth), Fullers Earth (clay), virgin material sized at 30/60 mesh.D7150 13
31、27. Method A7.1 Filter If the sample has visible particles, filter 225 mL of insulating liquid through a 1 or 1.2-m filter. Discard the first 25mL. Collect the remainder in a flask that has been cleaned, rinsed with distilled water and dried for 4 h at 100 6 5C. Flasks thathave been prepared beforeh
32、and are acceptable as long as all openings have been covered with aluminum foil.Alternatively, removethe plunger from a glass syringe and secure the tip of the barrel with a metal female luer-to-closed-end adapter. Place the barrelin a vertical position so that the large opening of the barrel is fac
33、ing up. Place 25 mL of insulating liquid in a 30 mL syringe or40 mL of oil in a 50 mL syringe. For flasks, use 100 mL.7.2 Sparge 100 mL enough of the filtered insulating liquid to conduct the testing with dry air for 30 6 3 min. The air is spargedSparge the air through the liquid at an approximate f
34、low rate of 200 mL per minute. A typical setup is Typical setups are shownin Fig. 1 and Fig. 2.7.3 Immediately If not already prepared in the syringes, immediately fill two (2) glass syringes (either 30- or 50-mL) with thesparged oil insulating liquid (25 mLin the 30-mLsyringe; 40 mLin the 50-mLsyri
35、nge). Make sure the syringe is filled with enoughoil test specimen to conduct a dissolved gas-in-oil analysis. The barrel and plunger of each glass syringe must be well-fitted toavoid air ingress at the junction of the plunger and barrel seal as the test specimen is being heated during the test proc
36、edure.7.4 Immediately remove any trapped bubbles from the syringe as described in Practice D3613D3612 and seal the syringe witha female-luer-to-closed-end adapter. adapter if not already done so. Do not use plastic stopcocks as they tend to leak and meltduring the heating phase of the procedure.7.5
37、Sparge another 100 mL of the filtered insulatingmore insulating liquid as described in 7.1 liquidthrough 7.2, but with drynitrogen for 30 6 3 min. The nitrogen is sparged through the insulating liquid at an approximate flow rate of 200 mL per minute.7.6 Repeat the procedures listed in 7.3 and 7.4 fo
38、r the nitrogen-sparged insulating liquid.7.7 Place the syringes with the test specimens laying down in the oven with the leur fitting slightly above horizontal. Heat allthe test specimens at 120 6 2C for 164 h 6 15 min. Remove the test specimens from the oven, allow to cool for at least 1 h.7.8 Afte
39、r the test specimens have been allowed to cool (Note 1), remove the female-luer-to-closed-end adapter and replace witha normal stopcocks. Expel a small amount of oil (2-5 mL) from the stopcock to remove any air that may have entered into thesyringe when changing out the female-luer-to-closed-end ada
40、pter.FIG. 1 Diagram of Sparging Setup with SyringeD7150 133NOTE 1Periodically check for air ingress during the cooling of the syringe. In those cases where it is visible, it is advisable to perform the test again.7.9 Perform dissolved gas-in-oil analysis (Note 2) on all four test specimens according
41、 to Test Method D3612. or IEC 60599.Whichever Test Method D3612 method is employed (A, B, or C), C) or IEC 60599, the following minimum detection limits mustbe met:Hydrogen: 5 ppmHydrocarbon gases: 1 ppmCarbon oxides: 25 ppmAtmospheric gases: 50 ppmHydrogen: 5 L/LHydrocarbon gases: 1 L/LCarbon oxide
42、s: 25 L/LAtmospheric gases: 50 L/LNOTE 2It is not usually necessary to conduct DGA analysis on the sparged samples after sparging but prior to heating to establish a baseline.Laboratory testing has shown that sparging samples containing up to 50 L/L of acetylene will fully remove or significantly re
43、duce all combustible gases.7.10 The test results are to conform to the following:Nitrogen and Oxygen: 12 % of the average of the two analysesHydrocarbon Gases: 10 % of the average of the two analyses and 2 ppmHydrogen: 10 % of the average of the two analyses and 3 ppm7.11 If the test results do not
44、conform to the provisions provided in 7.10, the results are to be discarded and the test repeated.7.12 Acetylene should not be detected. If acetylene is detected, then the results should be considered suspect and the processreviewed.7.13 Report the results as detailed in Section 9.8. Method B8.1 Pre
45、pare a stainless steel column such as the one shown in Fig. 23.Alternatively, construct a glass column (a vacuum filteringapparatus of 47 mm has worked well) using partial vacuum to pull the oil through as opposed to being pressurized. Make sure allthe parameters listed in 8.2 through 8.6 are adhere
46、d to.8.2 Fill the column with attapulgite clay filtering medium with a mesh size of 30/60 so that the final ratio is 1 g of clay to 30to 35 mL of insulating liquid. The clay can be preheated if desired (recommended range is 80 to 100C).8.3 Place the appropriate volume of insulating liquid in the sam
47、ple reservoir to achieve the correct clay to liquid ratio. No lessthan 275 mL of insulating liquid is to be used as the clay will absorb some of the insulating liquid and not all of it is recoverable.8.4 Heat the clay and insulating liquid with an external heating tape so that the exiting temperatur
48、e of the insulating liquid isbetween 60 and 70C.FIG. 2 Diagram of Attapulgite Clay Treatment ColumnSparging Setup with FlaskD7150 1348.5 The rate at which the insulating liquid is passed through the column is 3 to 5 mL per minute.8.6 Collect the eluent from the clay-filled column in a flask that mee
49、ts the requirements of 7.1.8.7 Continue with the testing procedure as detailed in 7.2 through 7.11.8.8 Report the results as detailed in Section 9.9. Report9.1 Report the following information:9.1.1 Sample Identification.9.1.2 Identify the sample as “As Received” or “After Being Processed by Clay Treatment”.9.1.3 Sparging gas.9.1.4 Volume concentration in the insulating liquid, of each component gas, expressed in parts per million L/L at STP (0Cand 760 torr).10. Precision and Bias10.1 PrecisionBecause this test method uses the analyti
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