ASTM D3300-00(2006)
(Test Method)Standard Test Method for Dielectric Breakdown Voltage of Insulating Oils of Petroleum Origin Under Impulse Conditions
Standard Test Method for Dielectric Breakdown Voltage of Insulating Oils of Petroleum Origin Under Impulse Conditions
SIGNIFICANCE AND USE
This test method is most commonly performed using a negative polarity point opposing a grounded sphere (NPS). The NPS breakdown voltage of fresh unused oils measured in the highly divergent field in this configuration depends on oil composition, decreasing with increasing concentration of aromatic, particularly polyaromatic, hydrocarbon molecules.
This test method may be used to evaluate the continuity of composition of an oil from shipment to shipment. The NPS impulse breakdown voltage of an oil can also be substantially lowered by contact with materials of construction, by service aging, and by other impurities. Test results lower than those expected for a given fresh oil may also indicate use or contamination of that oil.
Although polarity of the voltage wave has little or no effect on the breakdown strength of an oil in uniform fields, polarity does have a marked effect on the breakdown voltage of an oil in nonuniform electric fields.
Transient voltages may also vary over a wide range in both the time to reach crest value and the time to decay to half crest or to zero magnitude. The IEEE standard lightning impulse test (see 2.2) specifies a 1.2 by 50-μs negative polarity wave.
SCOPE
1.1 This test method covers the determination of the dielectric breakdown voltage of insulating oils in a highly divergent field under impulse conditions.
1.2 The values stated in inch-pound units are to be regarded as the standard.
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 determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation:D3300–00 (Reapproved 2006)
Standard Test Method for
Dielectric Breakdown Voltage of Insulating Oils of
Petroleum Origin Under Impulse Conditions
This standard is issued under the fixed designation D3300; 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 aging, and by other impurities. Test results lower than those
expected for a given fresh oil may also indicate use or
1.1 This test method covers the determination of the dielec-
contamination of that oil.
tric breakdown voltage of insulating oils in a highly divergent
3.3 Although polarity of the voltage wave has little or no
field under impulse conditions.
effect on the breakdown strength of an oil in uniform fields,
1.2 The values stated in inch-pound units are to be regarded
polaritydoeshaveamarkedeffectonthebreakdownvoltageof
as the standard.
an oil in nonuniform electric fields.
1.3 This standard does not purport to address all of the
3.4 Transient voltages may also vary over a wide range in
safety concerns, if any, associated with its use. It is the
both the time to reach crest value and the time to decay to half
responsibility of the user of this standard to establish appro-
crest or to zero magnitude. The IEEE standard lightning
priate safety and health practices and determine the applica-
impulse test (see 2.2) specifies a 1.2 by 50-µs negative polarity
bility of regulatory limitations prior to use.
wave.
2. Referenced Documents
4. Apparatus
2.1 ASTM Standards:
4.1 Impulse Generator, capable of producing a standard 1.2
D923 Practices for Sampling Electrical Insulating Liquids
by 50-µs full wave adjustable to positive or negative polarity.
D2864 Terminology Relating to Electrical Insulating Liq-
The generator shall have a nominal voltage rating of at least
uids and Gases
300 kV adjustable in 10-kV steps. Generators having a
2.2 IEEE Documents:
capability of 1000 W·s (1000 J) at 300 kV have been found
IEEE Standard 4-1995 Techniques for High-Voltage Test-
satisfactory.
ing
4.2 Voltage-Control Equipment—The controls shall include
3. Significance and Use
a suitable measuring device for predetermining the crest
voltage to within 65 %.Avoltage stabilizer is desirable at the
3.1 This test method is most commonly performed using a
input to the d-c power supply used for charging the impulse-
negativepolaritypointopposingagroundedsphere(NPS).The
generator capacitors.
NPS breakdown voltage of fresh unused oils measured in the
4.3 Electrodes:
highly divergent field in this configuration depends on oil
4.3.1 Theelectrodesshallconsistofapolishedsteelorbrass
composition, decreasing with increasing concentration of aro-
sphere of 0.5 in. (12.7 mm) diameter and a steel point. The
matic, particularly polyaromatic, hydrocarbon molecules.
point may be an ordinary steel phonograph needle with a 0.06
3.2 This test method may be used to evaluate the continuity
mm 6 20 % radius of curvature of point or a No. 18 Filter
of composition of an oil from shipment to shipment. The NPS
Point needle. Needles with drawn tips are not recommended.
impulse breakdown voltage of an oil can also be substantially
4.3.2 The effect of variation in the radius of curvature of
lowered by contact with materials of construction, by service
point is subject to further investigation. Both electrodes shall
be easily replaceable.
This test method is under the jurisdiction of ASTM Committee D27 on 4.4 Test Cell:
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
4.4.1 The test cell shall be made of a material of high
mittee D27.05 on Electrical Test.
dielectric strength and of such dimensions that the electrical
Current edition approved Nov. 1, 2006. Published January 2007. Originally
breakdown is restricted to the electrode gap.Test cell materials
approved in 1974. Last previous edition approved in 2000 as D3300 – 00. DOI:
10.1520/D3300-00R06.
shall resist attack by, and be insoluble in, any of the cleaning
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
the ASTM website. The following steel needle has been found satisfactory for this method: Dean
Available from the Institute of Electrical and Electronics Engineers, 445 Hoes No. 18 Filter Point Needle, available from John Dean, Inc., 20 Mechanic St.,
Lane, Piscataway, NJ 08855-1331. Putnam, CT 06260.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3300–00 (2006)
ortestliquidsused.TestcellssuchasthoseshowninFig.1and 6.1.3 The gap spacings shall be 1.0 in. (25.4 mm) for
Fig. 2 have been found satisfactory. point-to-sphere and 0.15 in. (3.8 mm) for sphere-to-sphere
4.4.2 The sphere electrode shall be rigidly fixed and the
electrode configuration.
point electrode mounted such that the gap may be adjusted
6.2 Cleaning—Degrease the cell and electrodes by rinsing
from zero to the required value.
them with reagent grade petroleum ether, washing with deter-
gent and hot water, rinsing thoroughly in hot tap water, and
5. Sampling
then rinsing them with distilled water. Dry the cell and
5.1 Obtain a sample of the liquid to be tested using
hardware in an oven for 2 h at approximately 105 to 110°C,
appropriate ASTM sampling apparatus in accordance with
remove, and store in a desiccator until needed.
Practices D923.
6.3 Daily Use—Use new or polished sphere electrodes at
6. Adjustments and Care of Electrodes and Test Cell
the beginning of each day’s testing. Discard the point electrode
and replace it after each breakdown; replace the sphere
6.1 Electrode Spacing:
electrodes after every five breakdowns when testing point-to-
6.1.1 For the cell shown in Fig. 1, reduce the electrode gap
sphere. More frequent replacement may be necessary when
to zero spacing. Proceed very carefully to avoid damaging the
testingsphere-to-sphere.Sphereelectrodesmaybecleanedand
point.Thepointofcontactshallbeestablishedelectricallywith
polished for reuse in point-to-sphere testing. However, the use
anohmmeter.Openthegaptothespecifi
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