ASTM D1830-99

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An American National Standard
Designation:D1830–99
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 D 1830; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope D 5423 Specification for Forced–Convection Laboratory
Ovens for Evaluation of Electrical Insulation.
1.1 This test method provides a procedure for evaluating
2.2 Institute of Electrical and Electronics Engineers Pub-
thermal endurance of flexible sheet materials by determining
lications:
dielectric breakdown voltage at room temperature after aging
IEEE No. 1 General Principles for Temperature Limits in
in air at selected elevated temperatures. Thermal endurance is
the Rating of Electrical Equipment
expressed in terms of a temperature index.
IEEE No. 101A Guide for the Statistical Analysis of Ther-
1.2 This test method is applicable to such solid electrical
mal Life Test Data (including Appendix A)
insulating materials as coated fabrics, dielectric films, compos-
2.3 IEC Publications:
ite laminates, and other materials where retention of flexibility
IEC216 GuidefortheDeterminationofThermalEndurance
after heat aging is of major importance (see Note 4).
Properties of Electrical Insulating Materials (Parts 1 and
1.3 This test method is not intended for the evaluation of
2)
rigid laminate materials nor for the determination of thermal
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
2. Referenced Documents temperature.
2 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
D 149 Test Method for Dielectric Breakdown Voltage and
of a property of a material, or a simple combination of
Dielectric Strength of Electrical Insulating Materials at
materials, is measured at room temperature and the values
Commercial Power Frequencies
plotted as a function of time.
D 374 Test Methods for Thickness of Solid Electrical Insu-
3.2 Definitions of Terms Specific to This Standard:
lation
3.2.1 thermal endurance graph—a straight-line plot of the
logarithm of thermal life in hours versus the reciprocal of the
This test method is under the jurisdiction of ASTM Committee D09 on
absolute aging temperature in kelvins (also known as the
Electrical and Electronic Insulating Materials and is the direct responsibility of
Arrhenius plot).
Subcommittee D09.19 on Dielectric Sheet and Roll Products
Current edition approved Oct. 10, 1999. Published November 1999. Originally
approved in 1961. Last previous edition approved in 1994 as D 1830 – 94.
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.
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D1830–99
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
6.1 Electrode Test Fixture—The fixture shall be in accor- 6.2 Dielectric Breakdown Test Set—The set shall meet the
requirements of Test Method D 149.
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 D 5423 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
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
D 374, having a pressor foot 6.35 6 0.03 mm (0.25 6 0.001 differ by at least 20°C.
in.) in diameter and an anvil of at least 50 mm (2 in.) in
9.2 Select exposure temperatures in accordance with those
diameter and shall exert a pressure of 0.17 6 0.01 MPa (25 6
shown in Table 1 as indicated by the anticipated temperature
2 psi) on 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.
7.2 A set of test specimens consists of five specimens.
10. Procedure
Prepare one set for initial (unaged) tests and five sets for each
10.1 WARNING—Lethal voltages are a potential hazard
aging temperature chosen (15 sets for three temperatures).
during the performance of this test. It is essential that the test
7.3 In the case of coated glass fabrics, make tests on
apparatus, and all associated equipment electrically connected
0.18-mm (0.007-in.) material having 0.08-mm (0.003-in.) or
to it, be properly designed and installed for safe operation.
0.10-mm (0.004-in.) base cloth, or on 0.25-mm (0.010-in.) or
Solidly ground all electrically conductive parts which it is
0.30-mm (0.012-in.) material having respectively 0.10-mm
possible for a person to contact during the test. Provide means
(0.004-in.) or 0.13-mm (0.005-in.) base cloth.
for use at the completion of any test to ground any parts which
NOTE 2—Experience has shown that unrealistically extended life data
were at high voltage during the test or have the potential for
usually result when the base fabrics of glass exceed the thicknesses
acquiring an induced charge during the test or retaining a
specified previously for the corresponding coated thicknesses. Similar
charge even after disconnection of the voltage source. Thor-
data are not available for other types of coated fabrics, and the user of this
oughly instruct all operators as to the correct procedures for
test method is urged to investigate this relationship to determine similar
performing tests safely. When making high voltage tests,
limitations, if any.
particularly in compressed gas or in oil, it is possible for the
8. Test Specimen Selection
energy released at breakdown to be suffıcient to result in fire,
explosion, or rupture of the test chamber. Design test equip-
8.1 Select test specimens from the sample in such manner
ment, test chambers and test specimens so as to minimize the
that they are randomly distributed among the sets.
possibility of suc
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