ASTM D3426-19
(Test Method)Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials Using Impulse Waves
Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials Using Impulse Waves
SIGNIFICANCE AND USE
5.1 It is possible for insulating materials used in high-voltage equipment to be subjected to transient voltage stresses, resulting from such causes as nearby lightning strokes. This is particularly true of apparatus such as transformers and switchgear used in electrical-power transmission and distribution systems. The ability of insulating materials to withstand these transient voltages is important in establishing the reliability of apparatus insulated with these materials.
5.2 Transient voltages caused by lightning will be of either positive or negative polarity. In a symmetrical field between identical electrodes, the polarity has no effect on the breakdown strength. However, with dissimilar electrodes there can be a pronounced polarity effect. It is common practice when using dissimilar electrodes, to make negative that electrode at which the higher gradient will appear. When asymmetrical electrodes are used for testing materials with which the tester has no previous experience or knowledge, it is recommended that he make comparative tests with positive polarity and negative polarity applied to the higher gradient, or smaller electrode, to determine which polarity produces the lower breakdown voltage.
5.3 The standard wave shape is a 1.2 by 50-μs wave, reaching peak voltage in approximately 1.2 μs and decaying to 50 % of peak voltage in approximately 50 μs after the beginning of the wave. This wave is intended to simulate a lightning stroke that strikes a system without causing failure on the system.
5.4 For most materials, the impulse dielectric strength will be higher than either its power frequency alternating voltage or its direct voltage dielectric strengths. Because of the short time involved, dielectric heating and other thermal effects are largely eliminated during impulse testing. Thus, the impulse test gives values closer to the intrinsic breakdown strength than do longer time tests. From comparisons of the impulse dielectric strength with th...
SCOPE
1.1 This test method covers the determination of dielectric strength of solid electrical insulating materials under simulated-lightning impulse conditions.
1.2 Procedures are given for tests using standard 1.2 by 50 μs full-wave impulses.
1.3 This test method is intended for use in determining the impulse dielectric strength of insulating materials, either using simple electrodes or functional models. It is not intended for use in impulse testing of apparatus.
1.4 This test method is similar to IEC Publication 243-3. All procedures in this test method are included in IEC 243-3. Differences between this test method and IEC 243-3 are largely editorial.
1.5 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 precaution statements are given in Section 9.
1.6 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.
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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: D3426 − 19
Standard Test Method for
Dielectric Breakdown Voltage and Dielectric Strength of
1
Solid Electrical Insulating Materials Using Impulse Waves
This standard is issued under the fixed designation D3426; 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 at Commercial Power Frequencies
D374 Test Methods for Thickness of Solid Electrical Insu-
1.1 This test method covers the determination of dielectric
lation (Metric) D0374_D0374M
strength of solid electrical insulating materials under
D2413 Practice for Preparation of Insulating Paper and
simulated-lightning impulse conditions.
Board Impregnated with a Liquid Dielectric
1.2 Procedures are given for tests using standard 1.2 by
2.2 American National Standard:
50 µs full-wave impulses.
C68.1 Techniques for Dielectric Tests (IEEE Standard No.
3
1.3 This test method is intended for use in determining the
4)
impulse dielectric strength of insulating materials, either using
2.3 IEC Standard:
simple electrodes or functional models. It is not intended for
Pub 243-3 Methods of Test for Electric Strength of Solid
use in impulse testing of apparatus.
Insulating Materials—Part 3:Additional Requirements for
3
1.4 This test method is similar to IEC Publication 243-3.All
Impulse Tests
procedures in this test method are included in IEC 243-3.
DifferencesbetweenthistestmethodandIEC243-3arelargely
3. Terminology
editorial.
3.1 Definitions:
1.5 This standard does not purport to address all of the
3.1.1 Reference Fig. 1 for the symbols mentioned.
safety concerns, if any, associated with its use. It is the
3.1.2 full-impulse-voltage wave, n—an aperiodic transient
responsibility of the user of this standard to establish appro-
voltage that rises rapidly to a maximum value, then falls less
priate safety, health, and environmental practices and deter-
rapidly to zero.
mine the applicability of regulatory limitations prior to use.
3.1.3 peak value of an impulse voltage wave, n—the maxi-
Specific precaution statements are given in Section 9.
mum value of voltage.
1.6 This international standard was developed in accor-
3.1.4 virtual-peak value of an impulse voltage wave, n—a
dance with internationally recognized principles on standard-
value derived from a recording of an impulse wave on which
ization established in the Decision on Principles for the
high-frequency oscillations or overshoot of limited magnitude
Development of International Standards, Guides and Recom-
maybepresent.Iftheoscillationshaveamagnitudeofnomore
mendations issued by the World Trade Organization Technical
than5 %ofthepeakvalueandafrequencyofatleast0.5MHz,
Barriers to Trade (TBT) Committee.
a mean curve may be drawn, the maximum amplitude of which
is the virtual-peak value. If the oscillations are of greater
2. Referenced Documents
magnitude, the voltage wave is not acceptable for standard
2
2.1 ASTM Standards:
tests.
D149 Test Method for Dielectric Breakdown Voltage and
3.1.5 virtual-front time of an impulse voltage wave,
DielectricStrengthofSolidElectricalInsulatingMaterials
n—equal to 1.67 times the interval t between the instants when
f
the voltage is 0.3 and 0.9 times the peak value (t , Fig. 1).
1
1
This test method is under the jurisdiction of ASTM Committee D09 on
3.1.6 virtual origin of an impulse voltage wave, n—thepoint
Electrical and Electronic Insulating Materials and is the direct responsibility of
of intersection O with the line of zero voltage of a line drawn
1
Subcommittee D09.12 on Electrical Tests.
through the points of 0.3 and 0.9 times the peak voltage on the
Current edition approved March 1, 2019. Published March 2019. Originally
front of an impulse voltage wave.
approved in 1975. Last previous edition approved in 2012 as D3426 – 97 (2012).
DOI: 10.1520/D3426-19.
2
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
3
Standards volume information, refer to the standard’s Document Summary page on Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D3426 − 19
FIG. 1 Full-Impulse Voltage Wave
3.1.7 virtual time to half-value of an impulse voltage wave, gear used in ele
...
This 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 previous version. Because
it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation: D3426 − 97 (Reapproved 2012) D3426 − 19
Standard Test Method for
Dielectric Breakdown Voltage and Dielectric Strength of
1
Solid Electrical Insulating Materials Using Impulse Waves
This standard is issued under the fixed designation D3426; 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
1.1 This test method covers the determination of dielectric strength of solid electrical insulating materials under simulated-
lightning impulse conditions.
1.2 Procedures are given for tests using standard 1.2 by 50 μs 50 μs full-wave impulses.
1.3 This test method is intended for use in determining the impulse dielectric strength of insulating materials, either using simple
electrodes or functional models. It is not intended for use in impulse testing of apparatus.
1.4 This test method is similar to IEC Publication 243-3. All procedures in this test method are included in IEC 243-3.
Differences between this test method and IEC 243-3 are largely editorial.
1.5 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific precaution statements are given in Section 9.
1.6 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at
Commercial Power Frequencies
D374 Test Methods for Thickness of Solid Electrical Insulation (Metric) D0374_D0374M
D2413 Practice for Preparation of Insulating Paper and Board Impregnated with a Liquid Dielectric
2.2 American National Standard:
3
C 68.1C68.1 Techniques for Dielectric Tests (IEEE Standard No. 4)
2.3 IEC Standard:
Pub 243-3 Methods of Test for Electric Strength of Solid Insulating Materials—Part 3: Additional Requirements for Impulse
3
Tests
3. Terminology
3.1 Definitions:
3.1.1 Reference should be made to Fig. 1 for the symbols mentioned.
3.1.2 full-impulse-voltage wave, n—an aperiodic transient voltage that rises rapidly to a maximum value, then falls less rapidly
to zero.
3.1.3 peak value of an impulse voltage wave, n—the maximum value of voltage.
1
This test method is under the jurisdiction of ASTM Committee D09 on Electrical and Electronic Insulating Materials and is the direct responsibility of Subcommittee
D09.12 on Electrical Tests.
Current edition approved Nov. 1, 2012March 1, 2019. Published November 2012March 2019. Originally approved in 1975. Last previous edition approved in 20042012
as D3426 – 97 (2012).(2004). DOI: 10.1520/D3426-97R12.10.1520/D3426-19.
2
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.
3
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D3426 − 19
FIG. 1 Full-Impulse Voltage Wave
3.1.4 virtual-peak value of an impulse voltage wave, n—a value derived from a recording of an impulse wave on which
high-frequency oscillations or overshoot of limited magnitude may be present. If the oscillations have a magnitude of no more than
5 % of the peak value and a frequency of at least 0.5 MHz, a mean curve may be drawn, the maximum amplitude of which is the
virtual-peak value. If the oscillations are of greater magnitude, the voltage wave is not acceptable for standard tests.
3.1.5 virtual-front time of an impulse voltage wave, n—equal to 1.67 times the interval t between the instants when the voltage
f
is 0.3 and 0.9 times the peak value (t , Fig. 1).
1
3.1.6 virtual origin of
...
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