ASTM D115-07(2012)
(Test Method)Standard Test Methods for Testing Solvent Containing Varnishes Used for Electrical Insulation
Standard Test Methods for Testing Solvent Containing Varnishes Used for Electrical Insulation
SIGNIFICANCE AND USE
Control—The following tests are useful for control purposes during the manufacture and use of varnishes, and for determining the uniformity of batches:
Specific gravity,
Viscosity,
Flash point, and
Nonvolatile matter by weight.
Performance—The following tests are useful for determining the performance of varnishes during application and use:
Drainage,
Time of drying,
Build,
Dielectric strength,
Thermal endurance,
Varnish compatibility,
Salt water proofness, and
Oil resistance.
SCOPE
1.1 These test methods cover tests for solvent containing varnishes primarily intended to provide electrical, mechanical, and chemical protection for electrical equipment. These test methods include tests for control and performance as follows:
ProcedureSection Build37-41 Dielectric Strength42-47 Drainage25-31 Flash Point17-19 Nonvolatile Matter20-24 Oil Resistance53-55 Preparation of Test Specimens 7 Specific Gravity 9-12 Temperature Index48-49 Time of Drying32-36 Varnish Compatibility50-52 Viscosity13-16
1.2 Where the entire test method is included in this standard, the precision and bias are not known unless given in the stated method.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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. For specific hazard statements, see Section 5.
Note 1—There is no equivalent IEC standard.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D115 − 07(Reapproved 2012)
Standard Test Methods for Testing
Solvent Containing Varnishes Used for Electrical Insulation
This standard is issued under the fixed designation D115; 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* D93 Test Methods for Flash Point by Pensky-Martens
Closed Cup Tester
1.1 These test methods cover tests for solvent containing
D149 Test Method for Dielectric Breakdown Voltage and
varnishes primarily intended to provide electrical, mechanical,
DielectricStrengthofSolidElectricalInsulatingMaterials
and chemical protection for electrical equipment. These test
at Commercial Power Frequencies
methods include tests for control and performance as follows:
D202 Test Methods for Sampling and Testing Untreated
Procedure Section
Paper Used for Electrical Insulation
Build 37–41
Dielectric Strength 42–47 D287 Test Method for API Gravity of Crude Petroleum and
Drainage 25–31
Petroleum Products (Hydrometer Method)
Flash Point 17–19
D295 Test Methods for Varnished Cotton Fabrics Used for
Nonvolatile Matter 20–24
Oil Resistance 53–55
Electrical Insulation
Preparation of Test Specimens 7
D374 Test Methods for Thickness of Solid Electrical Insu-
Specific Gravity 9–12
lation (Withdrawn 2013)
Temperature Index 48-49
Time of Drying 32–36
D580 Specification for Greige Woven Glass Tapes and
Varnish Compatibility 50–52
Webbings
Viscosity 13–16
D1475 Test Method For Density of Liquid Coatings, Inks,
1.2 Wheretheentiretestmethodisincludedinthisstandard,
and Related Products
the precision and bias are not known unless given in the stated
D1638 Method of Testing Urethane Foam Isocyanate Raw
method.
Materials
1.3 The values stated in SI units are to be regarded as the
D1932 Test Method for Thermal Endurance of Flexible
standard. The values given in parentheses are for information
Electrical Insulating Varnishes
only.
D2518 Specification for Woven Glass Fabrics for Electrical
Insulation (Withdrawn 2013)
1.4 This standard does not purport to address all of the
D2519 Test Method for Bond Strength of Electrical Insulat-
safety concerns, if any, associated with its use. It is the
ing Varnishes by the Helical Coil Test
responsibility of the user of this standard to establish appro-
D3145 Test Method for Thermal Endurance of Electrical
priate safety and health practices and determine the applica-
Insulating Varnishes by the Helical Coil Method
bility of regulatory limitations prior to use. For specific hazard
D3251 Test Method for Thermal Endurance Characteristics
statements, see Section 5.
of Electrical Insulating Varnishes Applied Over Film-
NOTE 1—There is no equivalent IEC standard.
Insulated Magnet Wire
D3278 Test Methods for Flash Point of Liquids by Small
2. Referenced Documents
Scale Closed-Cup Apparatus
2.1 ASTM Standards:
D3487 Specification for Mineral Insulating Oil Used in
D56 Test Method for Flash Point by Tag Closed Cup Tester
Electrical Apparatus
D5032 Practice for Maintaining Constant Relative Humidity
by Means of Aqueous Glycerin Solutions
These test methods are under the jurisdiction of ASTM Committee D09 on
D5423 Specification for Forced-Convection Laboratory Ov-
Electrical and Electronic Insulating Materials and are the direct responsibility of
Subcommittee D09.01 on Electrical Insulating Varnishes, Powders and Encapsulat-
ens for Evaluation of Electrical Insulation
ing Compounds.
E104 Practice for Maintaining Constant Relative Humidity
Current edition approved April 1, 2012. Published April 2012. Originally
by Means of Aqueous Solutions
approved in 1941. Last previous edition approved in 2007 as D115 – 07. DOI:
10.1520/D0115-07R12.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D115 − 07 (2012)
3. Terminology 4.1.4 Nonvolatile matter by weight.
3.1 Definitions: 4.2 Performance—The following tests are useful for deter-
mining the performance of varnishes during application and
3.1.1 dielectric strength—the voltage gradient at which
dielectric failure of the insulating material occurs under spe- use:
4.2.1 Drainage,
cific conditions of test.
4.2.2 Time of drying,
3.1.2 drainage—of an insulating varnish, a measure of the
4.2.3 Build,
variation in thickness from top to bottom of a varnish film
4.2.4 Dielectric strength,
obtained on the surface of a vertically dip coated panel after a
4.2.5 Thermal endurance,
specified time and temperature.
4.2.6 Varnish compatibility,
3.1.3 flash point—the lowest temperature of the specimen,
4.2.7 Salt water proofness, and
corrected to a pressure of 760 mm Hg (101.3 kPa), at which
4.2.8 Oil resistance.
application of an ignition source causes any vapor from the
specimen to ignite under specified conditions of test.
5. Hazards
3.1.4 nonvolatile matter—in insulating varnish, that portion
5.1 Warning—Do not use varnish at temperatures above
of a varnish which is not volatilized when exposed to specified
the flash point when inadequate ventilation, and the possibility
conditions; the value obtained is not necessarily equal to the
of flames or sparks exist. Store varnish in sealed containers.
calculated solids incorporated during compounding.
The precautions shall also apply to the handling of the reagents
3.1.4.1 Discussion—For example, the theoretical chemical
and solvents called for herein.
solids are often assumed to be the solid phase materials
incorporated in the varnish at the time of compounding. Many
6. Sampling
of these solid phase intermediate materials will lose volatile
6.1 For all tests the sample shall be taken from a represen-
fractions due to the specified conditions of the nonvolatile
tative lot of the varnish under study. To avoid skin formation
matter procedure. An example is phenolic resin.
and escape of solvents, protect the sample by keeping it at
3.1.5 oil resistance—of insulating varnish, a measure of the
room temperature in a nearly filled, tightly sealed container.
retention of properties after exposure to a specified oil under
specified conditions of test.
7. Preparation of Test Specimens
3.1.6 time of drying—of insulating varnish, the time re-
7.1 Selection of Substrate—The selection of the substrate is
quired for a film of varnish to dry to a tackfree state under
determined in part by application and in part by thermal class.
specified conditions.
Two types of substrates may be used: copper strip or glass
3.2 Definitions of Terms Specific to This Standard: cloth. Copper strip is generally not used for applications over
180°C (356°F) due to oxidation.
3.2.1 build, n—of an insulating varnish on copper, the
average thickness of varnish film on one side of a copper panel
7.2 Copper Base:
that has received a single coat of the varnish applied and
7.2.1 For tests that are to be performed upon the varnish as
measured under specified conditions.
a film on a copper base, copper strips 38 mm (1 ⁄2 in.) in width,
3.2.2 build, n—of an insulating varnish on glass cloth, the 200 mm (8 in.) in length, and 0.127 6 0.08 mm (0.005 6
average overall thickness of strips of glass cloth that have 0.0003 in.) in thickness shall be used, unless otherwise
received two dips of the varnish applied and measured under specified. Measure the thickness of these strips to the nearest
0.002 mm (0.0001 in.). Clean the strips with a suitable solvent
specified conditions.
(Note2),thenpolishthoroughlywithNo.000steelwool.Wipe
3.2.3 tack free, adj—condition when a varnish has reached
the strips free of any fingerprints or metal particles with the
the point that the surface can be touched lightly without a
solvent and a lint-free cloth. If the strips are not to be used
sensation of stickiness.
immediately, they should be kept stored in a noncorrosive
3.2.4 varnish, air-drying, n—a liquid resin system that
varnish solvent.
forms a dry, tack free coating, without the application of heat,
NOTE 2—Xylene and denatured alcohol (1:1) have been found to be
either through evaporation of solvent or by reaction with
suitable cleaning solvents.V.M.&.P. naphtha is a suitable solvent in which
atmospheric oxygen.
to store the strips.
3.2.5 varnish, baking, n—a liquid resin system that forms a
7.2.2 Prepare all varnish films for tests at 23 6 1°C (73.5 6
dry, tack free coating when exposed to elevated temperatures.
2°F) and 50 6 5 % relative humidity. The air of the room shall
be relatively free of dust by some satisfactory method of
4. Significance and Use
filtering.
4.1 Control—The following tests are useful for control
7.2.3 After the strips have been wiped clean and dry,
purposes during the manufacture and use of varnishes, and for
prepare the test specimens by dipping them into a tank of the
determining the uniformity of batches:
varnish that has been adjusted to a proper consistency and
4.1.1 Specific gravity, allowed to stand covered until free of bubbles (not to exceed 1
4.1.2 Viscosity,
h). Trial testing may be required to establish the proper
4.1.3 Flash point, and consistency. Proper consistency has been reached when the
D115 − 07 (2012)
strips are dipped in the varnish at a temperature of 23 6 1°C Apply the next coat by reverse dipping, except, withdraw
(73.5 6 2°F) and are withdrawn slowly and uniformly at the specimens as soon as immersed and drain as for the previous
rate of 100 mm (4 in.)/min., the average thickness of the film coat. Bake the second coat in accordance with the manufac-
remaining on each side of a strip when dry shall be 0.025 6 turer’s recommended schedule for a final coat.
0.005 mm (0.0010 6 0.0002 in.). 7.3.4 Measuring Specimen Thickness—Measure specimen
7.2.4 Calculate the average thickness by averaging at least thickness using a dead-weight dial-type micrometer in accor-
dance with Test Methods D374, Method C, except that the
six measurements taken along the length of the strip and over
3mm( ⁄8 in.) from either edge. Thickness measurements shall weight on the specimen shall be limited to 567 6 7 g (20 6
0.25 oz.) and the anvil surface upon which the specimen rests
be made in accordance with Test Methods D374.
shall be 51 mm (2 in.) in diameter. Allow the presser foot to
7.2.5 Itisrecognizedthatthethicknessofthefilmcannotbe
remain on the specimens about 2 s before taking a reading.
measured with the precision stated, but a close control of the
Where thickness measurements along a line or in an area are
thickness of the varnish film is desired. With the method
nonuniform,repeatthemeasurements,takingcaretoavoidfilm
specified, the actual average thickness should be within
abnormalities.
60.005 mm (60.0002 in.) of the measured thickness.
7.2.6 With air dry varnishes, except where time of drying is
8. Conditioning
the property being measured, following each dip, suspend the
specimens vertically in a dipping position and dry in dust-free 8.1 Condition the specimens as described in the individual
air for such times and at such temperatures as the user and the test procedures.
supplier agree are suitable. If necessary, readjust the consis-
SPECIFIC GRAVITY
tency of the varnish and dip the specimen in the reverse
direction to the first and air dry.
9. Terminology
7.2.7 Withbakingvarnishes,allowthespecimenstodrainat
9.1 Definitions:
a temperature of 23 6 1°C (73.5 6 2°F) then bake for such
9.1.1 specific gravity—the ratio of the weight of a unit
times and at such temperatures as the user and the supplier
volume of sample as compared with the weight of the same
agree are suitable. If necessary, readjust the consistency of the
unit volume of distilled water at 23 6 1°C (73.5 6 2°F).
varnishanddipthespecimeninthereversedirectiontothefirst
and bake.
10. Significance and Use
7.3 Glass Cloth Base:
10.1 Specific gravity indicates the relative weight per unit
7.3.1 For tests that are to be performed on the varnish as a
volume of a varnish. It is a useful test for control purposes.
combination with glass cloth, use a glass strip instead of a
copper strip. Prepare the strip from specimens 38 mm (1.5 in.)
11. Procedure
wide by approximately 250 mm (10 in.) long from heat-
11.1 Determine the specific gravity of the varnish by using
cleaned woven glass fabric (Note 3). The length shall be in the
a wide-mouth pycnometer (25-mLminimum capacity) at 23 6
direction of the warp threads.The fabric shall be Style No. 116
1°C (73.5 6 2°F). Refer toTest Method D1475. Determine the
as listed in Table number 1 of Specification D2518. The
specific gravity by dividing the weight of an equal volume of
volatile content of the heat-cleaned fabric shall not exceed
distilled water at the same temperature.
0.1 % as determined in accordance with the organic content
11.2 A hydrometer is another method for determining this
test of Specification D580 (Note 4). The strip form specimens
property, in accordance with Test Method D287 or Method
shall be kept in a Standard LaboratoryAtmosphere (see 7.2.2).
D1638.
7.3.2 Condition the heat-cleaned glass strips1hat 105°C
(221°F) and cool in a Standard LaboratoryAtmosphere before
12. Report
coating.
12.1 Report the following information:
NOTE 3—The strip form specimens may be stamped out of the woven
12.1.1 Identification of the varnish used, and
glass fabric by means of die and clicker.This technique causes the ends of
12.1.2 The specific gravity at 23 6 1°C (73.5 6 2°F),
the fibers to bind together and prevents the unraveling of the yarn.
reported to the third decimal place.
NOTE 4—Commercially heat-cleaned fiberglass fabric meeting this
volatile content is available.
VISCOSITY
7.3.3 Dipping and Curing—Condition the varnish to be
tested for a minimum of4hat Standard Laboratory Tempera-
13. Significance and Use
ture before coating the strips. Immerse specimens in the
13.1 Theviscositymeasurementmaybeusedtoindicatethe
varnish until bubbling stops. Withdraw at 100 mm (4 in.)/min.
flowing characteristics of a varnish.
and drain in a dipping and draining chamber in the same
13.2 Viscosity is also useful for control purposes during the
position as dipped for 30 min., or as agreed between the user
manufacture and use of a varnish.
and supplier. In order to facilitate dipping and curing and to
obtain smoother s
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