1、Designation: D 7150 05Standard Test Method for theDetermination of Gassing Characteristics of InsulatingLiquids Under Thermal Stress at Low Temperature1This standard is issued under the fixed designation D 7150; the number immediately following the designation indicates the year oforiginal adoption
2、or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes the procedures to determinethe low temperature (1
3、20C) gassing characteristics of insulat-ing liquids specifically and without the influence of otherelectrical apparatus materials or electrical stresses. This testmethod was primarily designed for insulating mineral oil. Itcan be applied to other insulating liquids in which dissolvedgas-in-oil analy
4、sis (Test Method D 3612) is commonly per-formed.1.2 This test method is particularly suited for detection ofthe phenomenon sometimes known as “stray gassing” and isalso referred to in CIGRE TF11 B39.1.3 This test method is performed on transformer insulatingliquids to determine the propensity of the
5、 oil to produce certaingases such as hydrogen and hydrocarbons at low temperatures.1.4 This test method details two procedures:1.5 Method A describes the procedure for determining thegassing characteristics of a new, unused insulating liquid, asreceived, at 120C for 164 h.1.6 Method B describes the
6、procedure for processing theinsulating liquid through an attapulgite clay column to removeorganic contaminants and other reactive groups that mayinfluence the gassing behavior of an insulating liquid, which issuspected of being contaminated. This procedure applies toboth new and used insulating liqu
7、ids.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and to determine theapplicability of regulatory limitations prior to use.2. Referen
8、ced Documents2.1 ASTM Standards:2D 1933 Specification for Nitrogen Gas as an ElectricalInsulating MaterialD 3612 Test Method for the Analysis of Gases Dissolved inElectrical Insulating Oil by Gas ChromatographyD 3613 Practice for Sampling Insulating Liquids for GasAnalysis and Determination of Water
9、 Content2.2 IEEE Document:3C 57.104 IEEE Guide for the Interpretation of Gases Gen-erated in Oil-Immersed Transformers, 19912.3 IEC Documents:4IEC 60599 Mineral oil-impregnated electrical equipment inservice Guide to the interpretation of dissolved and freegases analysis, 1999IEC 61464 Guide for the
10、 interpretation of dissolved gasanalysis (DGA) in bushings where oil is the impregnatingmedium of the main insulation (generally paper), 1998CIGRE TF11 B39 Gas formation tendency test for mineraltransformer oils, 2002.3. Terminology3.1 Definitions:3.1.1 stray gassing, nthe production of gases in an
11、insu-lating liquid due to heating, contamination or in combination.3.1.2 attapulgite clay, nalso termed Fullers Earth. Highlyadsorbent clay-like substance consisting mainly of hydratedaluminum silicates.4. Summary of Test Method4.1 Method AInsulating liquid is filtered through a mixedcellulose ester
12、 filter. A portion of the test specimen is spargedfor 30 min with dry air. A test specimen is then placed into aglass syringe, capped and aged at 120 6 2C for 164 h. The testis run in duplicate. The other portion of the test specimen issparged for 30 min with dry nitrogen. A test specimen is thenpla
13、ced into a glass syringe, capped and aged at 120C 6 2Cfor 164 h. The test is run in duplicate. After, the test specimenshave cooled, dissolved gas-in-oil analysis is then performedaccording to Test Method D 3612.4.2 Method BInsulating oil is passed through a heated (60to 70C) attapulgite clay column
14、 at a rate of 3 to 5 mL per1This test method is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gases and is the direct responsibility of Subcom-mittee D 27.03 on Analytical Tests.Current edition approved May 1, 2005. Published June 2005.2For referenced ASTM standard
15、s, 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.3Available from the Institute of Electrical and Electronic Engineers, Inc, (IEEE),445 Hoes
16、 Lane, Piscataway, NJ 08854; www.ieee.org4Available from the International Electrotechnical Commission, 3, rue deVaremb, P.O. Box 131 CH-1211, Geneva 20, Switzerland; www.iec.ch1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.minute.
17、The insulating liquid is contacted with the attapulgiteclay at a ratio of 1 g clay to 33 mL (range: 30 to 35 mL) ofinsulating liquid (0.25 lb clay: 1 gal of insulating liquid). Theinsulating liquid is collected and subjected to the testing asoutlined in 4.1.5. Significance and Use5.1 Generation of c
18、ombustible gases is used to determinethe condition of oil-filled electrical apparatus. Many years ofempirical evidence has yielded guidelines such as those givenin IEEE C 57.104, IEC 60599 and IEC 61464. Industry expe-rience has shown that electric and thermal faulted in oil-filledelectrical apparat
19、us are the usual sources that generate gases.Experience has shown that some of the gases could form in theoil at low temperatures or as a result of contamination, withoutany other influences.5.2 Some severely hydro-treated transformer oils subjectedto thermal stress and oils that contain certain typ
20、es of contami-nation may produce specific gases at lower temperatures thannormally expected for their generation and hence, falselyindicate abnormal operation of the electrical apparatus. Somenew oils have produced large amounts of gases, especiallyhydrogen, without the influence of other electrical
21、 apparatusmaterials or electrical stresses. This renders interpretation ofthe dissolved gas analysis more complicated.5.3 Heating for 164 h has been found to be a sufficientamount of time to reach a stable and characteristic gassingpattern.5.4 This method uses both dry air and dry nitrogen as thespa
22、rging gas. This is to reflect either a electrical apparatuspreservation system that allows oxygen to contact the oil or onethat is sealed from the outside atmosphere. Oils sparged withair generally produce much more hydrogen as a percentage ofthe total combustible gas content as compared to oils spa
23、rgedwith nitrogen as these produce more hydrocarbons in relationto hydrogen.6. Reagents and Materials6.1 Mixed Cellulose Ester Membrane Filter, consisting ofeither 1 or 1.2 m pore size, of correct diameter to fit in thefiltering apparatus listed in 6.2.6.2 Vacuum Filtering Apparatus, consisting of f
24、unnel reser-voir (250 mL or larger), clamp, base, stopper and receivingflask. The 47 mm size is the type most often used.6.3 Dry Nitrogen, meeting the requirements of SpecificationD 1933, Type III with the following exception: the totalhydrocarbon content must be 0.5 ppm. This type of gas issometime
25、s referred to as Ultra-High Purity (UHP).6.4 Dry Air, meeting the following requirements: 20 to 22 %oxygen, 3 ppm water, and 1 ppm total hydrocarbons. Thistype of gas is sometimes referred to as Zero Grade.6.5 Ovens, forced-draft, adjustable to 120 6 2C and adrying oven, convection or forced-draft,
26、or both, adjustable to100 6 5C.6.6 Syringes, glass, either 30 or 50 mL, either matchedplunger and barrel or precision ground to 0.006 6 0.001 mmmaximum spacing between the inside of the barrel to theoutside of the plunger for both the 30 mL and 50 mL syringes.6.7 Female-Luer-to-Closed-End-Adapter, n
27、ickel-platedbrass.6.8 Attapulgite Clay (Fullers Earth), virgin material sizedat 30/60 mesh.7. Method A7.1 Filter 225 mL of insulating liquid througha1or1.2-mfilter. Discard the first 25 mL. Collect the remainder in a flaskthat has been cleaned, rinsed with distilled water and dried for4hat1006 5C. F
28、lasks that have been prepared beforehandare acceptable as long as all openings have been covered withaluminum foil.7.2 Sparge 100 mL of the filtered insulating liquid with dryair for 30 6 3 min. The air is sparged through the liquid at anapproximate flow rate of 200 mL per minute. A typical setup is
29、shown in Fig. 1.7.3 Immediately fill two (2) glass syringes (either 30- or50-mL) with the sparged oil (25 mL in the 30-mL syringe; 40mL in the 50-mL syringe). Make sure the syringe is filled withenough oil to conduct a dissolved gas-in-oil analysis. Thebarrel and plunger of each glass syringe must b
30、e well-fitted toavoid air ingress at the junction of the plunger and barrel sealas the test specimen is being heated during the test procedure.7.4 Immediately remove any trapped bubbles from thesyringe as described in Practice D 3613 and seal the syringewith a female-luer-to-closed-end adapter. Do n
31、ot use plasticstopcocks as they tend to leak and melt during the heatingphase of the procedure.7.5 Sparge another 100 mL of the filtered insulating liquidwith dry nitrogen for 30 6 3 min. The nitrogen is spargedthrough the liquid at an approximate flow rate of 200 mL perminute.7.6 Repeat the procedu
32、res listed in 7.3 and 7.4 for thenitrogen-sparged insulating liquid.7.7 Place the syringes with the test specimens laying downin the oven with the leur fitting slightly above horizontal. Heatall the test specimens at 120 6 2C for 164 h 6 15 min.Remove the test specimens from the oven, allow to cool
33、for atleast 1 h.7.8 After the test specimens have been allowed to cool(Note 1), remove the female-luer-to-closed-end adapter andreplace with a normal stopcocks. Expel a small amount of oil(2-5 mL) from the stopcock to remove any air that may haveentered into the syringe when changing out the female-
34、luer-to-closed-end adapter.NOTE 1Periodically check for air ingress during the cooling of thesyringe. In those cases where it is visible, it is advisable to perform the testagain.7.9 Perform dissolved gas-in-oil analysis on all four testspecimens according to Test Method D 3612. Whichever TestMethod
35、 D 3612 method is employed (A, B, or C), thefollowing minimum detection limits must be met:Hydrogen: 5 ppmHydrocarbon gases: 1 ppmCarbon oxides: 25 ppmAtmospheric gases: 50 ppm7.10 The test results are to conform to the following:D7150052Nitrogen and Oxygen: 612 % of the average of the two analysesH
36、ydrocarbon Gases: 610 % of the average of the two analyses and 62 ppmHydrogen: 610 % of the average of the two analyses and 63 ppm7.11 If the test results do not conform to the provisionsprovided in 7.10, the results are to be discarded and the testrepeated.7.12 Acetylene should not be detected. If
37、acetylene isdetected, then the results should be considered suspect and theprocess reviewed.7.13 Report the results as detailed in Section 9.8. Method B8.1 Prepare a stainless steel column such as the one shownin Fig. 2. Alternatively, construct a glass column (a vacuumfiltering apparatus of 47 mm h
38、as worked well) using partialvacuum to pull the oil through as opposed to being pressurized.Make sure all the parameters listed in 8.2 through 8.6 areadhered to.8.2 Fill the column with attapulgite clay filtering mediumwith a mesh size of 30/60 so that the final ratio is1gofclayto 30 to 35 mL of ins
39、ulating liquid. The clay can be preheatedif desired (recommended range is 80 to 100C).8.3 Place the appropriate volume of insulating liquid in thesample reservoir to achieve the correct clay to liquid ratio. Noless than 275 mL of liquid is to be used as the clay will absorbsome of the liquid and not
40、 all of it is recoverable.8.4 Heat the clay and insulating liquid with an externalheating tape so that the exiting temperature of the insulatingliquid is between 60 and 70C.8.5 The rate at which the insulating liquid is passed throughthe column is 3 to 5 mL per minute.8.6 Collect the eluent from the
41、 clay-filled column in a flaskthat meets the requirements of 7.1.8.7 Continue with the testing procedure as detailed in 7.2through 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”
42、 or “After BeingProcessed by Clay Treatment”.9.1.3 Sparging gas.9.1.4 Volume concentration in the insulating liquid, of eachcomponent gas, expressed in parts per million at STP (0C and760 torr).10. Precision and Bias10.1 PrecisionBecause this test method uses the analyti-cal procedures in Test Metho
43、d D 3612, refer to the precisionstatements for that test method.10.2 BiasBecause this test method uses the analyticalprocedures in Test Method D 3612, refer to the bias statementsfor that test method.11. Keywords11.1 combustible gases; DGA; dissolved gases; dissolvedgas-in-oil; insulating oil; low t
44、emperature gassing characteris-tics; stray gassing; transformer oil, clay treatmentFIG. 1 Diagram of Sparging SetupD7150053ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expr
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47、attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United State
48、s. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).FIG. 2 Diagram of Attapulgite Clay Treatment ColumnD7150054
