ASTM D5374-93(1999)

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

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 20°C above the ambient temperature to 500°C 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, D5423, will eventually replace Specification D2436.
1.3 This standard does not purport to address all of the safety problems, 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: 09-Mar-1999
• 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

• Replaced By: ASTM D5374-93(2005) - 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: 10-Mar-1999
• Referred By: ASTM D3032-21a - Standard Test Methods for Hookup Wire Insulation
• Effective Date: 10-Mar-1999
• Referred By: ASTM D5423-23 - Standard Specification for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation
• Effective Date: 10-Mar-1999
• Referred By: ASTM D3012-19 - Standard Test Method for Thermal-Oxidative Stability of Polypropylene Using a Specimen Rotator Within an Oven
• Effective Date: 10-Mar-1999

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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.
An American National Standard
Designation: D 5374 – 93 (Reapproved 1999)
Standard Test Methods for
Forced-Convection Laboratory Ovens for Evaluation of
Electrical Insulation
This standard is issued under the fixed designation D 5374; 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.
1. Scope 4. Significance and Use
1.1 These test methods cover procedures for evaluating the 4.1 It is essential that ovens used for thermal evaluation of
characteristics of forced-convection ventilated electrically- insulating materials be capable of maintaining uniform condi-
heated ovens, operating over all or part of the temperature tions of temperature and air circulation over the extended
range from 20°C above the ambient temperature to 500°C and periods of time that are required for conducting these tests.
used for thermal endurance evaluation of electrical insulating Specification D 5423 specifies the permissible deviations from
materials. absolute uniformity that have been generally accepted interna-
1.2 These test methods are based on IEC Publication 216- tionallyfortheseovens.Thesetestmethodsincludeprocedures
4-1, and are technically identical to it. This compilation of test for measuring these deviations and other specified character-
methods and an associated specification, D 5423, have re- istics of the ovens.
placed Specification D 2436.
5. Apparatus
1.3 This standard does not purport to address all of the
5.1 Multi-PointRecordingPotentiometer,havingprovisions
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- for at least nine iron-constantan or chromel-alumel thermo-
couples, with scale readings to 0.1°C or less. Use of a data
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. processor or a data logger may be helpful in reducing the
number of calculations required.
2. Referenced Documents
5.2 Calibrated Iron-Constantan or Chromel-Alumel Ther-
2.1 ASTM Standards: mocouples, using 0.5-mm diameter or smaller wire and having
D 2436 Specification for Forced-Convection Laboratory a junction size not over 2.5 mm long. If calibrated thermo-
Ovens for Electrical Insulation couples are not available, thermocouples made from a single
D 5423 Specification for Forced-Convection Laboratory spool of thermocouple wire may be used provided that, when
Ovens for Evaluation of Electrical Insulation placedwithin10mmofeachotherwithouttouchinginanoven
2.2 Other Document: chamber at 200°C, they give values for temperature that do not
IEC Publication 216-4-1 Guide for the Determination of differ from each other by more than 0.2°C.
Thermal Endurance Properties of Electrical Insulating 5.3 A temperature measuring system other than thermo-
Materials, Part 4—Aging Ovens, Section 1—Single- couples and a potentiometer may be used, provided that the
Chamber Ovens sensitivity, accuracy, and response time are at least equivalent
to that of the equipment described above, and that the objec-
3. Terminology
tives of 6.2.3 relative to minimization of heat conduction
3.1 Refer to the terminology section of Specification
effects can be met.
D 5423. 5.4 Thermal Lag Time Specimen, consisting of a solid brass
cylinder, 10 mm in diameter and 55 mm long, with one
junction of a differential thermocouple soldered to the surface
These test methods are under the jurisdiction of ASTM Committee D-9 on
midway between the ends. The other junction of the thermo-
Electrical and Electronic Insulating Materials and are the direct responsibility of
couple must be capable of being moved at least 80 mm away
Subcommittee D09.17 on Thermal Characteristics.
Current edition approved June 15, 1993. Published August 1993. from the brass cylinder. An appropriate temperature indicator
Discontinued 1994; see 1993 Annual Book of ASTM Standards, Vol 10.01.
(as in 5.1, or other) must be provided for indication of
Annual Book of ASTM Standards, Vol 10.02.
temperaturedifferencestothenearest0.1°Casmeasuredbythe
Available from American National Standards Institute, 11 West 42nd St., 13th
differential thermocouple.
Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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.
D 5374 – 93 (1999)
NOTE 2—The density of air at one atmosphere and 20°C is 1.205 kg/m
5.5 Watt-Hour Meter, of the appropriate voltage and phase,
3.
capable of reading to the nearest 1.0 Wh or less.
6.1.9 If the rate of ventilation is not within the specified
6. Procedures
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
6.2 Temperature Variation, Gradient, and Fluctuation:
necessarily limited to, the vent ports, door, thermometer ports,
6.2.1 Summary of Test Method—Simultaneous temperature
and the space around the blower shaft (if the blower motor is
measurements are made at nine points in the oven chamber
mounted externally).
overaperiodoftimetodeterminethetimeandspacevariations
6.1.3 Install a watt-hour meter, as described in 5.5,inthe
of temperature. The time variation (temperature fluctuation)
oven electrical supply line.
and the space variation (temperature gradient) can be reported
6.1.4 Install a temperature sensor, such as a thermometer, 2
separately from temperature variation, which is the combina-
m to 3 m away from the oven, at least 1 m away from any solid
tion of the two.
object, and approximately level with the oven air intake. Use
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 and 5.2). Place one thermocouple in each of the eight
tion of power over a measured period of 30 to 40 min. Begin
corners of the chamber 50 to 60 mm from each wall, and the
and end the measuring period at corresponding points of the
ninth thermocouple within 25 mm of the geometric center of
cyclic temperature fluctuation; for example, the moment when
the cha
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