ASTM D3284-05(2019)
(Practice)Standard Practice for Combustible Gases in the Gas Space of Electrical Apparatus Using Portable Meters
Standard Practice for Combustible Gases in the Gas Space of Electrical Apparatus Using Portable Meters
SIGNIFICANCE AND USE
4.1 Arcing, partial discharge, and localized overheating in the insulation system of transformers result in chemical decomposition of the insulating oil and other insulating materials. This may generate various gases, some of which are combustible. Typically, gases are generated in the oil and then partitioned into the gas space according to their individual solubilities. Gases which are highly oil-soluble, such as acetylene, may not be in significant quantities in the gas space until an incipient fault has progressed to a very serious condition or failure of the transformer. Gases such as carbon monoxide and hydrogen which have low solubilities in oil can make up a large fraction of the combustible gases in the gas space. Detection of these gases is frequently the first available indication of a malfunction. Portable combustible gas meters are a convenient means of detecting the presence of generated gases.
4.2 Normal operation of a transformer may result in the formation of some combustible gases. The detection of an incipient fault by this method involves an evaluation of the amount of combustible gases present, the rate of generation of these gases, and their rate of escape from the transformer. Refer to IEEE C57.104 for detailed information on interpretation of gassing in transformers.
SCOPE
1.1 This field practice covers the detection and estimation of combustible gases in the gas blanket above the oil or in gas detector relays in transformers using portable instruments. It is applicable only with transformers using mineral oil as the dielectric fluid. Gases dissolved in the oil and noncombustible gases are not determined. A method of calibrating the instruments with a known gas mixture is included.
1.2 This practice affords a semi-quantitative estimate of the total combustible gases present in a gas mixture. If a more accurate determination of the total amount of combustible gases or a quantitative determination of the individual components is desired, use a laboratory analytical method, such as Test Method D3612.
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 7.
1.4 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.
General Information
Relations
Standards Content (Sample)
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: D3284 − 05 (Reapproved 2019)
Standard Practice for
Combustible Gases in the Gas Space of Electrical
Apparatus Using Portable Meters
This standard is issued under the fixed designation D3284; 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 2.2 IEEE Standard:
C57.104 Guide for the Interpretation of Gases Generated in
1.1 Thisfieldpracticecoversthedetectionandestimationof
Oil-Immersed Transformers
combustible gases in the gas blanket above the oil or in gas
detector relays in transformers using portable instruments. It is
3. Summary of Practice
applicable only with transformers using mineral oil as the
3.1 A sample of gas is diluted to a fixed ratio with air and
dielectric fluid. Gases dissolved in the oil and noncombustible
introduced into the meter at a pressure of approximately one
gases are not determined. A method of calibrating the instru-
atmosphere. Any combustible gases present are catalytically
ments with a known gas mixture is included.
oxidized on the surface of a sensor which is an element of a
1.2 This practice affords a semi-quantitative estimate of the
Wheatstone bridge. When combustible gases oxidize on the
total combustible gases present in a gas mixture. If a more
surface, they increase the temperature of the element, which
accurate determination of the total amount of combustible
changes its resistance and upsets the balance of the bridge.
gases or a quantitative determination of the individual compo-
3.2 The change in the resistance of the indicating elements
nents is desired, use a laboratory analytical method, such as
in the bridge circuit is indicated on a meter, which is usually
Test Method D3612.
calibrated to read in percent total combustible gas.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Significance and Use
responsibility of the user of this standard to establish appro-
4.1 Arcing, partial discharge, and localized overheating in
priate safety, health, and environmental practices and deter-
the insulation system of transformers result in chemical de-
mine the applicability of regulatory limitations prior to use.
compositionoftheinsulatingoilandotherinsulatingmaterials.
Specific precautionary statements are given in Section 7.
This may generate various gases, some of which are combus-
1.4 This international standard was developed in accor-
tible. Typically, gases are generated in the oil and then
dance with internationally recognized principles on standard-
partitioned into the gas space according to their individual
ization established in the Decision on Principles for the
solubilities. Gases which are highly oil-soluble, such as
Development of International Standards, Guides and Recom-
acetylene, may not be in significant quantities in the gas space
mendations issued by the World Trade Organization Technical
until an incipient fault has progressed to a very serious
Barriers to Trade (TBT) Committee.
condition or failure of the transformer. Gases such as carbon
monoxide and hydrogen which have low solubilities in oil can
2. Referenced Documents
make up a large fraction of the combustible gases in the gas
2.1 ASTM Standards:
space. Detection of these gases is frequently the first available
D3612 Test Method for Analysis of Gases Dissolved in
indication of a malfunction. Portable combustible gas meters
Electrical Insulating Oil by Gas Chromatography
are a convenient means of detecting the presence of generated
gases.
4.2 Normal operation of a transformer may result in the
This practice is under the jurisdiction of ASTM Committee D27 on Electrical
formation of some combustible gases. The detection of an
Insulating Liquids and Gases and is the direct responsibility of Subcommittee
incipient fault by this method involves an evaluation of the
D27.03 on Analytical Tests.
Current edition approved Dec. 1, 2019. Published December 2019. Originally amount of combustible gases present, the rate of generation of
approved in 1974. Last previous edition approved in 2011 as D3284 – 05(2011).
thesegases,andtheirrateofescapefromthetransformer.Refer
DOI: 10.1520/D3284-05R19.
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
Standards volume information, refer to the standard’s Document Summary page on Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE),
the ASTM website. 445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331, http://www.ieee.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3284 − 05 (2019)
to IEEE C57.104 for detailed information on interpretation of 7.1.3 Observe normal safety precautions when attaching
gassing in transformers. portable meters to transformers.
7.1.4 Verify that the gas space being sampled is at a positive
5. Interferences pressure before attempting to draw a sample.
5.1 In this practice it is essential that sufficient oxygen be
8. Calibration
present in the gas mixture to oxidize the combustible gases.
Since the gas blanket in a transformer is usually an inert gas, it 8.1 Prepare the instrument for operation and make zero
is necessary to dilute the sample gas with a known amount of
balance and voltage adjustments in accordance with the in-
air. This is usually accomplished by either introducing air and structions of the instrument manufacturer and Section 9.
the sample gas into the instrument in known ratios through
8.2 Mix the standard reference gas with air, and introduce it
fixed orifices, or by mixing known quantities of air and test
into the meter in exactly the same manner as used for the
specimen externally by displacement over water before intro-
sample gas from the transformer.
duction into the instrument. The working range of these
8.3 Turn the calibration adjustment so the meter indicates
instruments is b
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