ASTM D1830-99(2012)
(Test Method)Standard Test Method for Thermal Endurance of Flexible Sheet Materials Used for Electrical Insulation by the Curved Electrode Method
Standard Test Method for Thermal Endurance of Flexible Sheet Materials Used for Electrical Insulation by the Curved Electrode Method
SIGNIFICANCE AND USE
A major factor affecting the life of insulating materials is thermal degradation. Other factors, such as moisture and vibration, may cause failures after the material has been weakened by thermal degradation.
Electrical insulation is effective in electrical equipment only as long as it retains its physical and electrical integrity. Thermal degradation may be characterized by weight change, porosity, crazing, and generally a reduction in flexibility, and is usually accompanied by an ultimate reduction in dielectric breakdown voltage.
SCOPE
1.1 This test method provides a procedure for evaluating thermal endurance of flexible sheet materials by determining dielectric breakdown voltage at room temperature after aging in air at selected elevated temperatures. Thermal endurance is expressed in terms of a temperature index.
1.2 This test method is applicable to such solid electrical insulating materials as coated fabrics, dielectric films, composite laminates, and other materials where retention of flexibility after heat aging is of major importance (see Note 4).
1.3 This test method is not intended for the evaluation of rigid laminate materials nor for the determination of thermal endurance of those materials which are not expected or required to retain flexibility in actual service.
1.4 The values stated in acceptable metric units are to be regarded as the standard. The values in parentheses are for information only.
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 and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see 10.1.
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Standards Content (Sample)
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Designation: D1830 − 99 (Reapproved 2012)
Standard Test Method for
Thermal Endurance of Flexible Sheet Materials Used for
Electrical Insulation by the Curved Electrode Method
This standard is issued under the fixed designation D1830; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope lation (Metric) D0374_D0374M
D5423 Specification for Forced-Convection Laboratory Ov-
1.1 This test method provides a procedure for evaluating
ens for Evaluation of Electrical Insulation
thermal endurance of flexible sheet materials by determining
2.2 Institute of Electrical and Electronics Engineers Publi-
dielectric breakdown voltage at room temperature after aging
cations:
in air at selected elevated temperatures. Thermal endurance is
IEEENo.1 GeneralPrinciplesforTemperatureLimitsinthe
expressed in terms of a temperature index.
Rating of Electrical Equipment
1.2 This test method is applicable to such solid electrical
IEEE No. 101A Guide for the Statistical Analysis of Ther-
insulating materials as coated fabrics, dielectric films, compos-
mal Life Test Data (including Appendix A)
ite laminates, and other materials where retention of flexibility
2.3 IEC Publications:
after heat aging is of major importance (see Note 4).
IEC 216 Guide for the Determination of Thermal Endurance
Properties of Electrical Insulating Materials (Parts 1 and
1.3 This test method is not intended for the evaluation of
rigid laminate materials nor for the determination of thermal 2)
endurance of those materials which are not expected or
3. Terminology
required to retain flexibility in actual service.
3.1 Definitions:
1.4 The values stated in acceptable metric units are to be
3.1.1 temperature index, n—a number which permits com-
regarded as the standard. The values in parentheses are for
parison of the temperature/time characteristics of an electrical
information only.
insulatingmaterial,orasimplecombinationofmaterials,based
1.5 This standard does not purport to address all of the
on the temperature in degrees Celsius which is obtained by
safety concerns, if any, associated with its use. It is the
extrapolating theArrhenius plot of life versus temperature to a
responsibility of the user of this standard to establish appro-
specified time, usually 20 000 h.
priate safety and health practices and determine the applica-
3.1.2 thermal life, n—the time necessary for a specific
bility of regulatory limitations prior to use. For a specific
property of a material, or simple combination of materials, to
hazard statement, see 10.1.
degrade to a defined end point when aged at a specific
temperature.
2. Referenced Documents
3.1.3 thermal life curve, n—a graphical representation of
2.1 ASTM Standards:
thermal life at a specified aging temperature in which the value
D149 Test Method for Dielectric Breakdown Voltage and
of a property of a material, or a simple combination of
DielectricStrengthofSolidElectricalInsulatingMaterials
materials, is measured at room temperature and the values
at Commercial Power Frequencies
plotted as a function of time.
D374 Test Methods for Thickness of Solid Electrical Insu-
3.2 Definitions of Terms Specific to This Standard:
3.2.1 thermal endurance graph—a straight-line plot of the
This test method is under the jurisdiction of ASTM Committee D09 on
logarithm of thermal life in hours versus the reciprocal of the
Electrical and Electronic Insulating Materials and is the direct responsibility of
absolute aging temperature in kelvins (also known as the
Subcommittee D09.01 on Electrical Insulating Products
Current edition approved Jan. 1, 2012. Published January 2012. Originally Arrhenius plot).
approved in 1961. Last previous edition approved in 2005 as D1830 – 99 (2005).
DOI: 10.1520/D1830-99R12.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE),
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM 445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331.
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican 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
D1830 − 99 (2012)
4. Summary of Test Method
4.1 Specimens are aged in air at a minimum of three
temperatures above the expected use temperature of the mate-
rial. Dielectric breakdown voltage tests in air at room tempera-
ture are periodically made to determine the time of aging at
eachtesttemperaturerequiredtoreducethebreakdownvoltage
to a value of 12 kV/mm (300 V/mil) of original thickness.
These thermal life values are used to construct a thermal
endurance graph by means of which temperature indices may
be estimated corresponding to a thermal life as specified in the
material specification or as agreed upon between the user and
the supplier.
NOTE 1—This test method is not applicable to materials having an
initial dielectric breakdown voltage of less than 12 kV/mm (300V/mil) of
original thickness unless lower endpoint values are agreed upon or
indicated in the applicable material specifications.
5. Significance and Use
5.1 Amajorfactoraffectingthelifeofinsulatingmaterialsis
thermal degradation. Other factors, such as moisture and
vibration, may cause failures after the material has been
weakened by thermal degradation.
5.2 Electrical insulation is effective in electrical equipment
only as long as it retains its physical and electrical integrity.
Thermal degradation may be characterized by weight change,
porosity, crazing, and generally a reduction in flexibility, and is
usually accompanied by an ultimate reduction in dielectric
FIG. 2 Curved Electrode and Holder
breakdown voltage.
6. Apparatus
6.2 Dielectric Breakdown Test Set—The set shall meet the
6.1 Electrode Test Fixture—The fixture shall be in accor-
requirements of Test Method D149.
dance with the dimensions shown in Fig. 1 and Fig. 2.
Electrodes shall be of polished brass, with the upper electrode 6.3 Ovens—Ovens shall meet the requirements of Specifi-
having a mass of 1.8 6 0.05 kg (4.0 6 0.1 lb). cation D5423 Type II.
Insulation Thickness Dimension R Dimension H Dimension D
mm in. mm in. mm in. mm in.
0.18 0.007 4.55 0.179 8.15 0.321 8.71 0.344
0.25 0.010 6.48 0.255 6.22 0.245 2.45 0.490
0.30 0.012 7.77 0.306 4.93 0.194 4.94 0.588
Tolerance for R and D = 60.03 mm (0.001 in.)
Tolerance for H = 60.05 mm (0.002 in.)
FIG. 1 Curved Electrode Details
D1830 − 99 (2012)
6.4 Micrometer—The micrometer shall be of the dead- h is obtained and (2) it shall not be more than 25°C higher than
weight type specified in Methods C or D of Test Methods the estimated temperature index. Exposure temperatures shall
D374,havingapressorfoot6.35 60.03mm(0.25 60.001in.) differ by at least 20°C.
in diameter and an anvil of at least 50 mm (2 in.) in diameter
9.2 Select exposure temperatures in accordance with those
and shall exert a pressure of 0.17 6 0.01 MPa (25 6 2 psi) on
shown in Table 1 as indicated by the anticipated temperature
the anvil.
index of the material under test. It is recommended that
exploratory tests be first made at the highest temperature to
7. Test Specimens
obtain data establishing the validity of the 100 h minimum life
7.1 Test specimens shall be at least 250 mm (9.84 in.) long
requirement (see 9.1), and that this be used as a guide for the
by 130 mm (5.12 in.) wide, with the machine direction parallel
selection of the lower test temperatures.
to the longer direction.
10. Procedure
7.2 A set of test specimens consists of five specimens.
10.1 WARNING—Lethal voltages are a potential hazard
Prepare one set for initial (unaged) tests and five sets for each
during the performance of this test. It is essential that the test
aging temperature chosen (15 sets for three temperatures).
apparatus, and all associated equipment electrically connected
7.3 In the case of coated glass fabrics, make tests on
to it, be properly designed and installed for safe operation.
0.18-mm (0.007-in.) material having 0.08-mm (0.003-in.) or
Solidly ground all electrically conductive parts which it is
0.10-mm (0.004-in.) base cloth, or on 0.25-mm (0.010-in.) or
possible for a person to contact during the test. Provide means
0.30-mm (0.012-in.) material having respectively 0.10-mm
for use at the completion of any test to ground any parts which
(0.004-in.) or 0.13-mm (0.005-in.) base cloth.
were at high voltage during the test or have the potential for
NOTE 2—Experience has shown that unrealistically extended life data
acquiring an induced charge during the test or retaining a
usually result when the base fabrics of glass exceed the thicknesses
charge even after disconnection of the voltage source. Thor-
specified previously for the corresponding coated thicknesses. Similar
oughly instruct all operators as to the correct procedures for
data are not available for other types of coated fabrics, and the user of this
performing tests safely. When making high voltage tests,
test method is urged to investigate this relationship to determine similar
limitations, if any. particularly in compressed gas or in oil, it is possible for the
energy released at breakdown to be suffıcient to result in fire,
8. Test Specimen Selection
explosion, or rupture of the test chamber. Design test
8.1 Select test specimens from the sample in such manner equipment, test chambers and test specimens so as to minimize
that they are randomly distributed among the sets. the possibility of such occurrences and to eliminate the
possibility of personal injury. If the potential fo
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