ASTM D4733-98

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4733 – 98 An American National Standard
Standard Test Methods for
Solventless Electrical Insulating Varnishes
This standard is issued under the fixed designation D 4733; 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 at Commercial Power Frequencies
D 150 Test Methods for A-C Loss Characteristics and
1.1 These test methods cover solventless varnishes used
Permittivity (Dielectric Constant) of Solid Electrical Insu-
primarily as electrical, mechanical, and environmental protec-
lating Materials
tion for electrical equipment.
D 168 Test Method for Coke Residue of Creosote
1.2 These test methods are used on solventless varnishes
D 374 Test Methods for Thickness of Solid Electrical Insu-
that are applied by dipping (at atmospheric pressure conditions
lation
or under vacuum or other certain pressure), spraying, or
D 923 Test Method for Sampling Electrical Insulating Liq-
brushing for the purpose of impregnating or sealing electrical
uids
equipment. The following test methods are included:
D 1475 Test Method for Density of Paint, Varnish, Lacquer,
Property Tests (Uncured): Section
and Related Products
Density 7
Flash Point 8
D 1674 Methods of Testing Polymerizable Embedding
Gel Time 9
Compounds Used for Electrical Insulation
Monomer Content 10
D 1711 Terminology Relating to Electrical Insulation
Rheological Properties (Non-Newtonian) 11
Brookfield Viscosity 12
D 2196 Test Methods for Rheological Properties of Non-
Performance Property Tests (cured):
Newtonian Materials by Rotational (Brookfield) Viscom-
Bond Strength 13
eter
Coating Thickness 14
Dielectric Strength 15
D 2519 Test Method for Bond Strength of Electrical Insu-
Dielectric Strength-Using Metal Panels 16
lating Varnishes by the Helical Coil Test
Permittivity and Dissipation Factor 17
D 3056 Test Method for Gel Time of Solventless Varnishes
Build 18
D 3278 Test Method for Flash Point of Liquids by Small
1.3 The values stated in inch-pound units are to be regarded
Scale Closed-Cup Apparatus
as the standard. The values in parentheses are for information
D 3312 Test Method for Percent Reactive Monomer in
only.
Solventless Varnishes
1.4 This standard does not purport to address all of the
D 3487 Specification for Mineral Insulating Oil Used in
safety concerns, if any, associated with its use. It is the
Electrical Apparatus
responsibility of the user of this standard to establish appro-
D 3636 Practice for Sampling and Judging Quality of Solid
priate safety and health practices and determine the applica-
Electrical Insulating Materials
bility of regulatory limitations prior to use. Specific hazard
D 6054 Practice for Conditioning Electrical Insulating Ma-
statements are given in 8.3, 15.5.1, and 15.5.2.
terials for Testing
2. Referenced Documents
3. Terminology
2.1 ASTM Standards:
3.1 Definitions: For definitions of terms used in these test
D 93 Test Methods for Flash-Point by Pensky-Martens
methods, refer to Terminology D 1711.
Closed Cup Tester
3.1.1 gel time, n—of solventless varnish, the time required
D 115 Test Methods for Testing Solvent Containing Var-
at a specified temperature for a solventless varnish to be
nishes Used for Electrical Insulation
transformed from a liquid state to a gel as measured with a
D 149 Test Method for Dielectric Breakdown Voltage and
suitable gel time apparatus.
Dielectric Strength of Solid Electrical Insulating Materials
3.1.2 thixotropy, n—the property of a material to thin upon
isothermal agitation and to thicken upon subsequent rest.
These test methods are under the jurisdiction of ASTM Committee D-9 on
Electrical and Electronic Insulating Materials and is the direct responsibility of
Subcommittee D09.01 on Electrical Insulating Varnishes, Powders, and Encapsu-
lating Compounds. Annual Book of ASTM Standards, Vol 04.10.
Current edition approved Nov. 10, 1998. Published March 1999. Originally Annual Book of ASTM Standards, Vol 10.03.
published as D 4733 – 87. Last previous edition D 4733 – 94. Annual Book of ASTM Standards, Vol 06.01.
2 7
Annual Book of ASTM Standards, Vol 05.01. Discontinued; see the 1992 Annual Book of ASTM Standards, Vol 10.01.
3 8
Annual Book of ASTM Standards, Vol 10.01. Annual Book of ASTM Standards, Vol 10.02.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4733
3.1.3 varnish, electrical insulating, n— a liquid resin sys- TEST METHODS
tem that is applied to and cured on electrical components
7. Density
providing electrical, mechanical and environmental protection.
7.1 Scope—This test method covers the measurement of the
3.1.3.1 Discussion—There are two types of electrical insu-
lating varnish—solvent-containing and solventless. The density using a pycnometer. It is particularly applicable where
the fluid has too high a viscosity for other methods of testing
solvent-containing varnish is solution, dispersion or emulsion
of a polymer or a mixture of polymers in a volatile, nonre- density. In this test method the density will be expressed as
pounds per gallon (grams per milliliter) at 70 to 77°F (20 to
actable liquid. The solventless type is a liquid resin system free
of volatile, nonreactable solvents. 25°C).
7.2 Procedure—Test for density in accordance with Test
4. Significance and Use
Method D 1475.
4.1 The test methods referenced in these test methods are 7.3 Report—Report the following information:
useful for control purposes during the manufacture and use of 7.3.1 Identification of the test sample,
solventless varnishes. 7.3.2 The test temperature to the nearest 0.2°F (0.1°C),
7.3.3 Density to the nearest 0.01 lb/gal (0.001 g/mL), and
5. Sampling
7.3.4 The mean, the range, and the number of replicate
5.1 Accurate sampling, whether of the complete contents or
determinations.
only parts thereof, is extremely important from the standpoint
8. Flash Point
of evaluating the quality of the product sampled. In most cases,
the detection of contaminants that are not ordinarily dispersed 8.1 Scope—This test method covers the determination of
uniformly through the liquid being sampled such as water or the flash point of solventless varnishes. There are two types of
solid particles, necessitates taking samples at specific locations materials involved:
where the contaminants are likely to be found. For a liquid 8.1.1 Those varnishes having a flash point above 230°F
having a specific gravity less than one, water and other (110°C), and
impurities are most likely to be found on the bottom; whereas 8.1.2 Those varnishes having a flash point below 230°F
in the case of liquids having a specific gravity greater than one, (110°C).
these impurities are most likely to be found on the surface. 8.2 Summary of Test Method—A specified amount of
5.2 Sampling Fluids Exhibiting Newtonian Viscosity: sample is added to the instrument. The temperature of the
5.2.1 Sample solventless varnishes having an approximate material is increased at a constant rate until a small flame
viscosity of 25 cP (0.025 Pa·s) or less at 100°F (37.8°C) using ignites the vapor of the specimen in the tester and propagates
the sampling device shown in Fig. 1 of Test Method D 923. a flame across its surface. The temperature at ignition is taken
However, if the temperature of the material is below room as the flash point.
temperature or if the humidity is above 75 % relative humidity, 8.3 This test method should be used to measure and describe
sample using an aspirator-type sampling device as shown in the response of materials, products, or assemblies to heat and
Fig. 2 of Test Method D 923. flame under controlled conditions and should not be used to
5.2.2 Sample solventless varnishes having a viscosity from describe or appraise the fire hazard or fire risk of materials,
25 to 650 cP (0.025 to 0.65 Pa·s) at 100°F (37.8°C) and where products, or assemblies under actual fire conditions. However,
contact with the atmosphere must be avoided, use a pressure- results of this test may be used as elements of a fire hazard
type sampling device as shown in Fig. 3 of Test Method D 923. assessment or a fire risk assessment which takes into account
5.2.3 Sample solventless varnishes having a viscosity above all of the factors which are pertinent to an assessment of the
650 cP at 100°F at 73 6 10°F (23 6 5°C). Open the container fire hazard of a particular end use.
and mix slowly so as not to entrap air. When the material is 8.4 Procedure:
homogeneous, take samples from two or three places on the 8.4.1 Test the materials of 8.1.1 in accordance with Test
surface and mix together. Methods D 93.
5.3 Sampling Fluids Exhibiting Non-Newtonian Viscosity: 8.4.2 Test the materials of 8.1.2 in accordance with Test
5.3.1 Sample solventless varnishes exhibiting non- Method D 3278.
Newtonian viscosity in accordance with 5.2.3. 8.5 Report—Report information in accordance with the
5.4 Use sample containers and sampling procedures in report section of the test method used.
accordance with Test Method D 923.
9. Gel Time
5.5 When a sampling method is needed to determine
whether a lot meets the requirements of a material specifica- 9.1 Scope—This test method covers the determination of
gel time of a solventless varnish mixed with a reactor or
tion, use Practice D 3636 as a guide.
catalyst and exposed to elevated temperatures.
6. Conditioning
9.2 Significance and Use—Knowledge of gel time is impor-
6.1 Condition test specimens at standard laboratory condi- tant for determining shelf life, batch uniformity, and processing
tion as specified in Practice D 6054. characteristics.
6.2 Deaerate specimens to be used for property evaluation 9.3 Procedure—Test for gel time in accordance with Test
before curing using the vacuum technique recommended by the Method D 3056.
varnish manufacturer. 9.4 Report—Report the following information:
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4733
9.4.1 Identification of the material, 13. Bond Strength
9.4.2 The reactor or catalyst and quantity used should be
13.1 Scope—This test method covers the determination of
stated if the reactor or catalyst is supplied in a separate
the bond strength of an electrical insulating varnish when
package,
applied to a helical coil.
9.4.3 Gel time to the nearest 0.1 min,
13.2 Significance and Use—Values obtained by flexural test
9.4.4 Temperature of the bath, and
can provide information with regard to the bond strength of a
9.4.5 Liquid used in the bath.
particular varnish in combination with a particular wire when
measured under the prescribed conditions.
10. Monomer Content
13.3 Procedure—Perform the test in accordance with Test
10.1 Scope—This test method covers the determination of
Method D 2519.
the percent monomer having a vapor pressure exceeding 0.1
13.3.1 Apply the varnish in the “as received” condition,
Torr (13 Pa) at 77°F (25°C).
13.3.2 Apply only one coat of varnish, and
10.2 Significance and Use—The percent of reactive mono-
13.3.3 Use film-insulated magnet wire.
mer in a solventless varnish will affect the viscosity, handling,
13.4 Report—Report information in accordance with Test
and processing properties of the uncured resin. The amount of
Method D 2519.
reactive monomer may also affect the physical and electrical
13.5 Precision and Bias:
properties of the cured resin.
13.5.1 Precision—See Test Method D 2519 for a statement
10.3 Procedure—Test for the monomer content in accor-
of bias.
dance with Test Method D 3312.
13.5.2 Bias—See Test Method D 2519 for a statement of
10.4 Report—Report the following information:
bias.
10.4.1 Identification of the solventless varnish, and
10.4.2 Percent reactive monomer.
14. Coating Thickness
11. Rheological Properties (Non-Newtonian) 14.1 Scope:
14.1.1 This test method is used to determine the thickness of
11.1 Scope—This test method covers the determination of
a coating obtained with a solventless varnish.
the rheological properties of solventless varnishes that are
14.1.2 The shear history of the varnish immediately preced-
non-newtonian in character.
ing the test may have an appreciable effect on the coating
11.2 Significance and Use—This test method is used to test
thickness obtained. This test method specifies the degree of
solventless varnishes that are thixotropic in nature and require
shear of the sample and the rate of withdrawal of the specimen
specific treatment of the sample in order to determine this
in order to arrive at a reproducible buildup on a test specimen.
property.
14.2 Apparatus:
11.3 Procedure—Test for thixotropy in accordance with
14.2.1 Device, capable of withdrawing a specimen at 4
Test Method D 2196, Method B or C.
in./min (100 mm/min).
11.4 Report—Report information as specified in Test
14.2.2 Water Bath, or conditioned room controlled to a
Method D 2196.
temperature of 75 6 2°F (24 6 1°C).
12. Brookfield Viscosity
14.2.3 Thermometer, with a range of 32 to 212°F (0 to
100°C).
12.1 Scope—This test method covers the determination of
14.2.4 Test Panel, consisting of a steel strip 3 in. (75 mm) in
viscosity for liquids having flow properties approaching those
width, 5 in. (125 mm) in length, and 0.010 in. (0.25 mm) in
of the newtonian solutions.
thickness.
12.2 Apparatus:
14.2.4.1 The thickness is determined by measuring the
12.2.1 Brookfield Viscometer.
thickness at 2 in. (50 mm) below the top and at 4 in. (100 mm)
12.2.2 Thermometer.
below the top. An average of these two is the thickness of the
12.2.3 Water Bath.
bare panel. Thickness measurements shall be made in accor-
12.2.4 Stirrer.
dance with Test Methods D 374.
12.3 Procedure:
14.3 Procedure:
12.3.1 Bring the specimen to a temperature of 77 6 2°F (25
14.3.1 Bring the test specimen to a temperature of 756 2°F
6 1.0°C) using a water bath and stirrer if necessary. Allow the
(24 6 1°C) and pour slowly into a suitable container. Do not
specimen to sit in the water bath at 77 6 2°F until no bubbles
trap air in the varnish.
are visible in the specimen.
14.3.2 Slowly lower the test panel into the varnish.
12.3.2 Make all measurements with the Brookfield viscom-
eter at 77 6 2°F (25 6 1.0°C). 14.3.3 Place the container with the varnish and panel in a
12.4 Report—Report information as specified in Test constant-tempera
...