ASTM D7150-05
(Test Method)Standard Test Method for the Determination of Gassing Characteristics of Insulating Liquids Under Thermal Stress at Low Temperature
Standard Test Method for the Determination of Gassing Characteristics of Insulating Liquids Under Thermal Stress at Low Temperature
SIGNIFICANCE AND USE
Generation of combustible gases is used to determine the condition of oil-filled electrical apparatus. Many years of empirical evidence has yielded guidelines such as those given in IEEE C57.104, IEC 60599 and IEC 61464. Industry experience has shown that electric and thermal faulted in oil-filled electrical apparatus are the usual sources that generate gases. Experience has shown that some of the gases could form in the oil at low temperatures or as a result of contamination, without any other influences.
Some severely hydro-treated transformer oils subjected to thermal stress and oils that contain certain types of contamination may produce specific gases at lower temperatures than normally expected for their generation and hence, falsely indicate abnormal operation of the electrical apparatus. Some new oils have produced large amounts of gases, especially hydrogen, without the influence of other electrical apparatus materials or electrical stresses. This renders interpretation of the dissolved gas analysis more complicated.
Heating for 164 h has been found to be a sufficient amount of time to reach a stable and characteristic gassing pattern.
This method uses both dry air and dry nitrogen as the sparging gas. This is to reflect either a electrical apparatus preservation system that allows oxygen to contact the oil or one that is sealed from the outside atmosphere. Oils sparged with air generally produce much more hydrogen as a percentage of the total combustible gas content as compared to oils sparged with nitrogen as these produce more hydrocarbons in relation to hydrogen.
SCOPE
1.1 This test method describes the procedures to determine the low temperature (120C) gassing characteristics of insulating liquids specifically and without the influence of other electrical apparatus materials or electrical stresses. This test method was primarily designed for insulating mineral oil. It can be applied to other insulating liquids in which dissolved gas-in-oil analysis (Test Method D 3612) is commonly performed.
1.2 This test method is particularly suited for detection of the phenomenon sometimes known as "stray gassing" and is also referred to in CIGRE TF11 B39.
1.3 This test method is performed on transformer insulating liquids to determine the propensity of the oil to produce certain gases 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 the gassing characteristics of a new, unused insulating liquid, as received, at 120C for 164 h.
1.6 Method B describes the procedure for processing the insulating liquid through an attapulgite clay column to remove organic contaminants and other reactive groups that may influence the gassing behavior of an insulating liquid, which is suspected of being contaminated. This procedure applies to both new and used insulating liquids.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D7150 − 05
StandardTest Method for the
Determination of Gassing Characteristics of Insulating
Liquids Under Thermal Stress at Low Temperature
This standard is issued under the fixed designation D7150; 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 2. Referenced Documents
1.1 This test method describes the procedures to determine 2.1 ASTM Standards:
D1933 Specification for Nitrogen Gas as an Electrical Insu-
the low temperature (120°C) gassing characteristics of insulat-
ing liquids specifically and without the influence of other lating Material
D3612 Test Method for Analysis of Gases Dissolved in
electrical apparatus materials or electrical stresses. This test
method was primarily designed for insulating mineral oil. It Electrical Insulating Oil by Gas Chromatography
D3613 Practice for Sampling Insulating Liquids for Gas
can be applied to other insulating liquids in which dissolved
gas-in-oil analysis (Test Method D3612) is commonly per- Analysis and Determination ofWater Content (Withdrawn
2007)
formed.
2.2 IEEE Document:
1.2 This test method is particularly suited for detection of
C 57.104 IEEE Guide for the Interpretation of Gases Gen-
the phenomenon sometimes known as “stray gassing” and is
erated in Oil-Immersed Transformers, 1991
also referred to in CIGRE TF11 B39.
2.3 IEC Documents:
1.3 This test method is performed on transformer insulating
IEC 60599 Mineral oil-impregnated electrical equipment in
liquids to determine the propensity of the oil to produce certain
service – Guide to the interpretation of dissolved and free
gases such as hydrogen and hydrocarbons at low temperatures.
gases analysis, 1999
IEC 61464 Guide for the interpretation of dissolved gas
1.4 This test method details two procedures:
analysis (DGA) in bushings where oil is the impregnating
1.5 Method A describes the procedure for determining the
medium of the main insulation (generally paper), 1998
gassing characteristics of a new, unused insulating liquid, as
CIGRE TF11 B39 Gas formation tendency test for mineral
received, at 120°C for 164 h.
transformer oils, 2002.
1.6 Method B describes the procedure for processing the
3. Terminology
insulating liquid through an attapulgite clay column to remove
organic contaminants and other reactive groups that may
3.1 Definitions:
influence the gassing behavior of an insulating liquid, which is
3.1.1 stray gassing, n—the production of gases in an insu-
suspected of being contaminated. This procedure applies to
lating liquid due to heating, contamination or in combination.
both new and used insulating liquids.
3.1.2 attapulgite clay, n—also termed Fullers Earth. Highly
1.7 This standard does not purport to address all of the adsorbent clay-like substance consisting mainly of hydrated
safety concerns, if any, associated with its use. It is the
aluminum silicates.
responsibility of the user of this standard to establish appro-
priate safety and health practices and to determine the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
applicability of regulatory limitations prior to use.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
The last approved version of this historical standard is referenced on
This test method is under the jurisdiction of ASTM Committee D27 on www.astm.org.
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom- Available from the Institute of Electrical and Electronic Engineers, Inc, (IEEE),
mittee D27.03 on Analytical Tests. 445 Hoes Lane, Piscataway, NJ 08854; www.ieee.org
Current edition approved May 1, 2005. Published June 2005. DOI: 10.1520/ Available from the International Electrotechnical Commission, 3, rue de
D7150-05. Varembé, P.O. Box 131 CH-1211, Geneva 20, Switzerland; www.iec.ch
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7150 − 05
4. Summary of Test Method 6.3 Dry Nitrogen, meeting the requirements of Specification
D1933, Type III with the following exception: the total
4.1 Method A—Insulating liquid is filtered through a mixed
hydrocarbon content must be <0.5 ppm. This type of gas is
cellulose ester filter. A portion of the test specimen is sparged
sometimes referred to as Ultra-High Purity (UHP).
for 30 min with dry air. A test specimen is then placed into a
glasssyringe,cappedandagedat120 62°Cfor164h.Thetest
6.4 DryAir,meetingthefollowingrequirements:20to22%
is run in duplicate. The other portion of the test specimen is
oxygen, <3 ppm water, and <1 ppm total hydrocarbons. This
sparged for 30 min with dry nitrogen. A test specimen is then
type of gas is sometimes referred to as Zero Grade.
placed into a glass syringe, capped and aged at 120°C 6 2°C
6.5 Ovens, forced-draft, adjustable to 120 6 2°C and a
for 164 h. The test is run in duplicate.After, the test specimens
drying oven, convection or forced-draft, or both, adjustable to
have cooled, dissolved gas-in-oil analysis is then performed
100 6 5°C.
according to Test Method D3612.
6.6 Syringes, glass, either 30 or 50 mL, either matched
4.2 Method B—Insulating oil is passed through a heated (60
plunger and barrel or precision ground to 0.006 6 0.001 mm
to 70°C) attapulgite clay column at a rate of 3 to 5 mL per
maximum spacing between the inside of the barrel to the
minute. The insulating liquid is contacted with the attapulgite
outside of the plunger for both the 30 mL and 50 mL syringes.
clay at a ratio of 1 g clay to 33 mL (range: 30 to 35 mL) of
insulating liquid (0.25 lb clay: 1 gal of insulating liquid). The
6.7 Female-Luer-to-Closed-End-Adapter , nickel-plated
insulating liquid is collected and subjected to the testing as
brass.
outlined in 4.1.
6.8 Attapulgite Clay (Fuller’s Earth), virgin material sized
5. Significance and Use
at 30/60 mesh.
5.1 Generation of combustible gases is used to determine
7. Method A
the condition of oil-filled electrical apparatus. Many years of
empirical evidence has yielded guidelines such as those given
7.1 Filter 225 mLof insulating liquid througha1or 1.2-µm
in IEEE C57.104, IEC 60599 and IEC 61464. Industry expe-
filter. Discard the first 25 mL. Collect the remainder in a flask
rience has shown that electric and thermal faulted in oil-filled
that has been cleaned, rinsed with distilled water and dried for
electrical apparatus are the usual sources that generate gases.
4hat100 6 5°C. Flasks that have been prepared beforehand
Experience has shown that some of the gases could form in the
are acceptable as long as all openings have been covered with
oil at low temperatures or as a result of contamination, without
aluminum foil.
any other influences.
7.2 Sparge 100 mL of the filtered insulating liquid with dry
5.2 Some severely hydro-treated transformer oils subjected
air for 30 6 3 min. The air is sparged through the liquid at an
to thermal stress and oils that contain certain types of contami-
approximate flow rate of 200 mLper minute.Atypical setup is
nation may produce specific gases at lo
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.