ASTM D5374-93(2005)

Standard Test Methods for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation

SIGNIFICANCE AND USE
It is essential that ovens used for thermal evaluation of insulating materials be capable of maintaining uniform conditions of temperature and air circulation over the extended periods of time that are required for conducting these tests. Specification D 5423 specifies the permissible deviations from absolute uniformity that have been generally accepted internationally for these ovens. These test methods include procedures for measuring these deviations and other specified characteristics of the ovens.
SCOPE
1.1 These test methods cover procedures for evaluating the characteristics of forced-convection ventilated electrically-heated ovens, operating over all or part of the temperature range from 20C above the ambient temperature to 500C and used for thermal endurance evaluation of electrical insulating materials.
1.2 These test methods are based on IEC Publication 216-4-1, and are technically identical to it. This compilation of test methods and an associated specification, D 5423, have replaced Specification D 2436.
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.

General Information

• Status: Historical
• Publication Date: 31-Aug-2005
• ICS: 29.035.01 - Insulating materials in general
• Technical Committee: D09 - Electrical and Electronic Insulating Materials
• Drafting Committee: D09.17 - Fire and Thermal Properties

Relations

• Replaces: ASTM D5374-93(1999) - Standard Test Methods for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation
• Effective Date: 01-Sep-2005
• Referred By: ASTM D3045-18 - Standard Practice for Heat Aging of Plastics Without Load
• Effective Date: 01-Sep-2005
• Referred By: ASTM D3012-19 - Standard Test Method for Thermal-Oxidative Stability of Polypropylene Using a Specimen Rotator Within an Oven
• Effective Date: 01-Sep-2005
• Referred By: ASTM D3032-21a - Standard Test Methods for Hookup Wire Insulation
• Effective Date: 01-Sep-2005
• Referred By: ASTM D5423-23 - Standard Specification for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation
• Effective Date: 01-Sep-2005

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D5374 − 93(Reapproved 2005) An American National Standard
Standard Test Methods for
Forced-Convection Laboratory Ovens for Evaluation of
Electrical Insulation
This standard is issued under the fixed designation D5374; 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 3. Terminology
1.1 These test methods cover procedures for evaluating the 3.1 Refer to the terminology section of Specification
characteristics of forced-convection ventilated electrically- D5423.
heated ovens, operating over all or part of the temperature
4. Significance and Use
range from 20°C above the ambient temperature to 500°C and
used for thermal endurance evaluation of electrical insulating
4.1 It is essential that ovens used for thermal evaluation of
materials.
insulating materials be capable of maintaining uniform condi-
1.2 These test methods are based on IEC Publication 216- tions of temperature and air circulation over the extended
periods of time that are required for conducting these tests.
4-1, and are technically identical to it. This compilation of test
methods and an associated specification, D5423, have replaced Specification D5423 specifies the permissible deviations from
absolute uniformity that have been generally accepted interna-
Specification D2436.
tionallyfortheseovens.Thesetestmethodsincludeprocedures
1.3 This standard does not purport to address all of the
for measuring these deviations and other specified character-
safety concerns, if any, associated with its use. It is the
istics of the ovens.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Apparatus
bility of regulatory limitations prior to use.
5.1 Multi-PointRecordingPotentiometer, having provisions
2. Referenced Documents for at least nine iron-constantan or chromel-alumel
thermocouples, with scale readings to 0.1°C or less. Use of a
2.1 ASTM Standards:
data processor or a data logger may be helpful in reducing the
D2436 Specification for Forced-Convection Laboratory Ov-
number of calculations required.
ens for Electrical Insulation (Withdrawn 1994)
D5423 Specification for Forced-Convection Laboratory Ov- 5.2 Calibrated Iron-Constantan or Chromel-Alumel
ens for Evaluation of Electrical Insulation
Thermocouples, using 0.5-mm diameter or smaller wire and
having a junction size not over 2.5 mm long. If calibrated
2.2 Other Document:
thermocouples are not available, thermocouples made from a
IEC Publication 216-4-1 Guide for the Determination of
single spool of thermocouple wire may be used provided that,
Thermal Endurance Properties of Electrical Insulating
when placed within 10 mm of each other without touching in
Materials, Part 4—Aging Ovens, Section 1—Single-
an oven chamber at 200°C, they give values for temperature
Chamber Ovens
that do not differ from each other by more than 0.2°C.
5.3 A temperature measuring system other than thermo-
1 couples and a potentiometer may be used, provided that the
These test methods are under the jurisdiction of ASTM Committee D09 on
Electrical and Electronic Insulating Materials and are the direct responsibility of
sensitivity, accuracy, and response time are at least equivalent
Subcommittee D09.17 on Thermal Characteristics.
to that of the equipment described above, and that the objec-
Current edition approved Sept. 1, 2005. Published October 2005. Originally
tives of 6.2.3 relative to minimization of heat conduction
approved in 1993. Last previous edition approved in 1999 as D5374 – 93 (1999).
effects can be met.
DOI: 10.1520/D5374-93R05.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.4 Thermal Lag Time Specimen, consisting of a solid brass
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
cylinder, 10 mm in diameter and 55 mm long, with one
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
junction of a differential thermocouple soldered to the surface
The last approved version of this historical standard is referenced on
midway between the ends. The other junction of the thermo-
www.astm.org.
couple must be capable of being moved at least 80 mm away
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036. from the brass cylinder. An appropriate temperature indicator
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5374 − 93 (2005)
(as in 5.1, or other) must be provided for indication of
∆T = difference in temperature between the oven and the
temperaturedifferencestothenearest0.1°Casmeasuredbythe
ambient room temperature, °C.
differential thermocouple.
NOTE 1—This volume includes space outside the testing chamber. The
amount of this additional space depends on the physical design of the
5.5 Watt-Hour Meter, of the appropriate voltage and phase,
oven.
capable of reading to the nearest 1.0 Wh or less.
NOTE 2—The density of air at one atmosphere and 20°C is 1.205 kg/m
3.
6. Procedures
6.1.9 If the rate of ventilation is not within the specified
limits for the oven, adjust the vents and dampers and repeat
6.1 Rate of Ventilation:
6.1.7 through 6.1.8.
6.1.1 Summary of Test Method—The rate of ventilation is
6.1.10 Repeat 6.1.2 through 6.1.9, except heat the oven to
calculated using determinations of (1) the average power
the maximum temperature at which the oven may be used.
required to maintain the oven at a given temperature with its
6.1.11 Report the following information:
ports open and (2) the average power required to maintain the
6.1.11.1 Identification of the oven,
oven at the same temperature with its ports closed. The test is
6.1.11.2 Date and location of test,
conducted at 100°C and at the maximum temperature at which
6.1.11.3 Test temperatures, and
the oven may be used.
6.1.11.4 Rate of ventilation at each temperature.
6.1.2 Seal all openings into the oven, including, but not
necessarily limited to, the vent ports, door, thermometer ports,
6.2 Temperature Variation, Gradient, and Fluctuation:
and the space around the blower shaft (if the blower motor is
6.2.1 Summary of Test Method—Simultaneous temperature
mounted externally).
measurements are made at nine points in the oven chamber
6.1.3 Install a watt-hour meter, as described in 5.5,inthe
overaperiodoftimetodeterminethetimeandspacevariations
oven electrical supply line.
of temperature. The time variation (temperature fluctuation)
6.1.4 Install a temperature sensor, such as a thermometer, 2
and the space variation (temperature gradient) can be reported
m to 3 m away from the oven, at least 1 m away from any solid
separately from temperature variation, which is the combina-
object, and approximately level with the oven air intake. Use
tion of the two.
the oven temperature indicator to measure the internal tem-
6.2.2 Set the vents and dampers in the oven to the settings
perature of the oven.
needed for the specified range of rate of ventilation.
6.1.5 Raise the oven temperature to 100 6 2°C. When the
6.2.3 Install nine thermocouples in the oven chamber (see
temperature of the oven has stabilized, measure the consump-
5.1 an
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