ASTM D4733-03(2009)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D4733 − 03(Reapproved 2009) An American National Standard
Standard Test Methods for
Solventless Electrical Insulating Varnishes
This standard is issued under the fixed designation D4733; 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 These test methods cover solventless varnishes used
D93 Test Methods for Flash Point by Pensky-Martens
primarily as electrical, mechanical, and environmental protec-
Closed Cup Tester
tion for electrical equipment.
D115 Test Methods for Testing Solvent Containing Var-
1.2 These test methods are used on solventless varnishes
nishes Used for Electrical Insulation
that are applied by dipping (at atmospheric pressure conditions
D149 Test Method for Dielectric Breakdown Voltage and
or under vacuum or other certain pressure), spraying, or DielectricStrengthofSolidElectricalInsulatingMaterials
brushing for the purpose of impregnating or sealing electrical at Commercial Power Frequencies
D150 Test Methods forAC Loss Characteristics and Permit-
equipment. The following test methods are included:
tivity (Dielectric Constant) of Solid Electrical Insulation
Property Tests (Uncured): Section
Density 7 D168 Test Method for Coke Residue of Creosote (With-
Flash Point 8
drawn 2006)
Gel Time 9
D374 Test Methods for Thickness of Solid Electrical Insu-
Monomer Content 10
Rheological Properties (Non-Newtonian) 11
lation
Brookfield Viscosity 12
D923 Practices for Sampling Electrical Insulating Liquids
Performance Property Tests (cured):
D1475 Test Method For Density of Liquid Coatings, Inks,
Bond Strength 13
Coating Thickness 14
and Related Products
Dielectric Strength 15
D1711 Terminology Relating to Electrical Insulation
Dielectric Strength-Using Metal Panels 16
D2196 Test Methods for Rheological Properties of Non-
Permittivity and Dissipation Factor 17
Build 18
Newtonian Materials by Rotational (Brookfield type)
Viscometer
1.3 The values stated in inch-pound units are to be regarded
D2519 Test Method for Bond Strength of Electrical Insulat-
as the standard. The values in parentheses are for information
ing Varnishes by the Helical Coil Test
only.
D3056 Test Method for Gel Time of Solventless Varnishes
1.4 This standard does not purport to address all of the
D3278 Test Methods for Flash Point of Liquids by Small
safety concerns, if any, associated with its use. It is the Scale Closed-Cup Apparatus
responsibility of the user of this standard to establish appro- D3312 Test Method for Percent Reactive Monomer in Sol-
ventless Varnishes
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. Specific hazard D3487 Specification for Mineral Insulating Oil Used in
Electrical Apparatus
statements are given in 8.3, 15.5.1, and 15.5.2.
D3636 Practice for Sampling and Judging Quality of Solid
NOTE 1—This test method is related to IEC 60455. Since both methods
Electrical Insulating Materials
contain multiple test procedures, many procedures are technically equiva-
D6054 Practice for Conditioning Electrical Insulating Mate-
lent while others differ significantly.
rials for Testing
These test methods are under the jurisdiction of ASTM Committee D09 on
Electrical and Electronic Insulating Materials and is the direct responsibility of For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Subcommittee D09.01 on Electrical Insulating Varnishes, Powders and Encapsulat- contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ing Compounds. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Oct. 1, 2009. Published February 2010. Originally the ASTM website.
approved in 1987. Last previous edition approved in 2003 as D4733 – 03. DOI: The last approved version of this historical standard is referenced on
10.1520/D4733-03R09. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4733 − 03 (2009)
2.2 IEC Standards 5.3 Sampling Fluids Exhibiting Non-Newtonian Viscosity:
IEC 60455 Resin Based Reactive Compunds Used for Elec- 5.3.1 Sample solventless varnishes exhibiting non-
trical Insulation Newtonian viscosity in accordance with 5.2.3.
5.4 Use sample containers and sampling procedures in
3. Terminology
accordance with Test Method D923.
3.1 Definitions:
5.5 When a sampling method is needed to determine
3.1.1 For definitions of terms used in these test methods,
whether a lot meets the requirements of a material specifica-
refer to Terminology D1711.
tion, use Practice D3636 as a guide.
3.1.2 gel time, n—of solventless varnish, the time required
at a specified temperature for a solventless varnish to be
6. Conditioning
transformed from a liquid state to a gel as measured with a
6.1 Condition test specimens at standard laboratory condi-
suitable gel time apparatus.
tion as specified in Practice D6054.
3.1.3 thixotropy, n—the property of a material to thin upon
isothermal agitation and to thicken upon subsequent rest. 6.2 Deaerate specimens to be used for property evaluation
beforecuringusingthevacuumtechniquerecommendedbythe
3.1.4 varnish, electrical insulating, n—a liquid resin system
varnish manufacturer.
that is applied to and cured on electrical components providing
electrical, mechanical, and environmental protection.
TEST METHODS
3.1.4.1 Discussion—There are two types of electrical insu-
lating varnish—solvent-containing and solventless. The
7. Density
solvent-containing varnish is solution, dispersion, or emulsion
7.1 Scope—This test method covers the measurement of the
of a polymer or a mixture of polymers in a volatile, nonre-
density using a pycnometer. It is particularly applicable where
actable liquid.The solventless type is a liquid resin system free
the fluid has too high a viscosity for other methods of testing
of volatile, nonreactable solvents.
density. In this test method the density will be expressed as
4. Significance and Use pounds per gallon (grams per millilitre) at 70 to 77°F (20 to
25°C).
4.1 The test methods referenced in these test methods are
useful for control purposes during the manufacture and use of 7.2 Procedure—Test for density in accordance with Test
solventless varnishes.
Method D1475.
7.3 Report—Report the following information:
5. Sampling
7.3.1 Identification of the test sample,
5.1 Accurate sampling, whether of the complete contents or
7.3.2 The test temperature to the nearest 0.2°F (0.1°C),
only parts thereof, is extremely important from the standpoint
7.3.3 Density to the nearest 0.01 lb/gal (0.001 g/mL), and
of evaluating the quality of the product sampled. In most cases,
7.3.4 The mean, the range, and the number of replicate
the detection of contaminants that are not ordinarily dispersed
determinations.
uniformly through the liquid being sampled such as water or
solid particles, necessitates taking samples at specific locations
8. Flash Point
where the contaminants are likely to be found. For a liquid
8.1 Scope—Thistestmethodcoversthedeterminationofthe
having a specific gravity less than one, water and other
flash point of solventless varnishes. There are two types of
impurities are most likely to be found on the bottom; whereas
materials involved:
in the case of liquids having a specific gravity greater than one,
8.1.1 Those varnishes having a flash point above 230°F
these impurities are most likely to be found on the surface.
(110°C), and
5.2 Sampling Fluids Exhibiting Newtonian Viscosity:
8.1.2 Those varnishes having a flash point below 230°F
5.2.1 Sample solventless varnishes having an approximate
(110°C).
viscosity of 25 cP (0.025 Pa·s) or less at 100°F (37.8°C) using
8.2 SummaryofTestMethod—Aspecifiedamountofsample
the sampling device shown in Fig. 1 of Test Method D923.
is added to the instrument. The temperature of the material is
However, if the temperature of the material is below room
increasedataconstantrateuntilasmallflameignitesthevapor
temperature or if the humidity is above 75 % relative humidity,
of the specimen in the tester and propagates a flame across its
sample using an aspirator-type sampling device as shown in
surface. The temperature at ignition is taken as the flash point.
Fig. 2 of Test Method D923.
5.2.2 Sample solventless varnishes having a viscosity from 8.3 Thistestmethodshouldbeusedtomeasureanddescribe
25 to 650 cP (0.025 to 0.65 Pa·s) at 100°F (37.8°C) and where the response of materials, products, or assemblies to heat and
contact with the atmosphere must be avoided, use a pressure- flame under controlled conditions and should not be used to
type sampling device as shown in Fig. 3 of Test Method D923. describe or appraise the fire hazard or fire risk of materials,
5.2.3 Sample solventless varnishes having a viscosity above products, or assemblies under actual fire conditions. However,
650 cP at 100°F at 73 6 10°F (23 6 5°C). Open the container results of this test may be used as elements of a fire hazard
and mix slowly so as not to entrap air. When the material is assessment or a fire risk assessment which takes into account
homogeneous, take samples from two or three places on the all of the factors which are pertinent to an assessment of the
surface and mix together. fire hazard of a particular end use.
D4733 − 03 (2009)
8.4 Procedure: 12. Brookfield Viscosity
8.4.1 Test the materials of 8.1.1 in accordance with Test
12.1 Scope—This test method covers the determination of
Methods D93.
viscosity for liquids having flow properties approaching those
8.4.2 Test the materials of 8.1.2 in accordance with Test
of the newtonian solutions.
Method D3278.
12.2 Apparatus:
8.5 Report—Report information in accordance with the
12.2.1 Brookfield Viscometer.
report section of the test method used.
12.2.2 Thermometer.
12.2.3 Water Bath.
9. Gel Time
12.2.4 Stirrer.
9.1 Scope—Thistestmethodcoversthedeterminationofgel
12.3 Procedure:
time of a solventless varnish mixed with a reactor or catalyst
12.3.1 Bring the specimen to a temperature of 77 6 2°F (25
and exposed to elevated temperatures.
6 1.0°C) using a water bath and stirrer if necessary.Allow the
specimen to sit in the water bath at 77 6 2°F until no bubbles
9.2 Significance and Use—Knowledge of gel time is impor-
are visible in the specimen.
tantfordeterminingshelflife,batchuniformity,andprocessing
12.3.2 Make all measurements with the Brookfield viscom-
characteristics.
eter at 77 6 2°F (25 6 1.0°C).
9.3 Procedure—Test for gel time in accordance with Test
12.4 Report—Report information as specified in Test
Method D3056.
Method D2196.
9.4 Report—Report the following information:
12.5 Precision and Bias:
9.4.1 Identification of the material,
12.5.1 Precision—See Test Method D2196 for a statement
9.4.2 The reactor or catalyst and quantity used should be
of precision.
stated if the reactor or catalyst is supplied in a separate
12.5.2 Bias—See Test Method D2196 for a statement of
package,
bias.
9.4.3 Gel time to the nearest 0.1 min,
9.4.4 Temperature of the bath, and
13. Bond Strength
9.4.5 Liquid used in the bath.
13.1 Scope—This test method covers the determination of
10. Monomer Content the bond strength of an electrical insulating varnish when
applied to a helical coil.
10.1 Scope—This test method covers the determination of
the percent monomer having a vapor pressure exceeding 0.1 13.2 Significance and Use—Values obtained by flexural test
can provide information with regard to the bond strength of a
Torr (13 Pa) at 77°F (25°C).
particular varnish in combination with a particular wire when
10.2 Significance and Use—The percent of reactive mono-
measured under the prescribed conditions.
mer in a solventless varnish will affect the viscosity, handling,
13.3 Procedure—Perform the test in accordance with Test
and processing properties of the uncured resin. The amount of
Method D2519.
reactive monomer may also affect the physical and electrical
properties of the cured resin.
13.4 Report—Report information in accordance with Test
Method D2519.
10.3 Procedure—Test for the monomer content in accor-
dance with Test Method D3312.
13.5 Precision and Bias:
13.5.1 Precision—See Test Method D2519 for a statement
10.4 Report—Report the following information:
of bias.
10.4.1 Identification of the solventless varnish, and
13.5.2 Bias—See Test Method D2519 for a statement of
10.4.2 Percent reactive monomer.
bias.
11. Rheological Properties (Non-Newtonian)
14. Coating Thickness
11.1 Scope—This test method covers the determination of
14.1 Scope:
the rheological properties of solventless varnishes that are
14.1.1 Thistestmethodisusedtodeterminethethicknessof
non-newtonian in character.
a coating obtained with a solventless varnish.
11.2 Significance and Use—This test method is used to test
14.1.2 The shear history of the varnish immediately preced-
solventless varnishes that are thixotropic in nature and require
ing the test may have an appreciable effect on the coating
specific treatment of the sample in order to determine this
thickness obtained. This test method specifies the degree of
property.
shear of the sample and the rate of withdrawal of the specimen
11.3 Procedure—TestforthixotropyinaccordancewithTest in order to arrive at a reproducible buildup on a test specimen.
Method D2196, Method B or C.
14.2 Apparatus:
11.4 Report—Report information as specified in Test 14.2.1 Device, capable of withdrawing a specimen at ap-
Method D2196. proximately 4 in./min (100 mm/min).
D4733 − 03 (2009)
14.2.2 Water Bath, or conditioned room controlled to a 15.1.2 SeetheSignificanceandUsesectionofTestMethods
temperature of 75 6 2°F (24 6 1°C). D149 for further information on this subject.
14.2.3 Thermometer, with a range of 32 to 212°F (0 to
15.2 Apparatus:
100°C).
15.2.1 Electrical apparatus is as described in Test Method
14.2.4 Test Panel, consisting of a steel or aluminum strip 3
D149.
in. (75 mm) in width, 5 in. (125 mm) in length, and
15.2.2 Electrodes are opposing cylinders 50 mm (2 in.) in
0.005–0.032 in. (0.12–0.81 mm) in thickness.
diameter and 25 mm (1 in.) in length, with the edges rounded
14.2.4.1 The thickness is determined by measuring the
to a radius of 6.4 mm ( ⁄4 in.). Use clean insulating oil meeting
thickness at 2 in. (50 mm) below the top and at 4 in. (100 mm)
the requirements of Specification D3487, Type I or Type II as
below the top. An average of these two is the thickness of the
the
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