ASTM D2132-12(2018)
(Test Method)Standard Test Method for Dust-and-Fog Tracking and Erosion Resistance of Electrical Insulating Materials
Standard Test Method for Dust-and-Fog Tracking and Erosion Resistance of Electrical Insulating Materials
SIGNIFICANCE AND USE
6.1 Method—It is possible that electrical insulation in service will fail as a result of tracking, erosion, or a combination of both, if exposed to high relative humidity and contamination environments. This is particularly true of organic insulations in outdoor applications where the surface of the insulation becomes contaminated by deposits of moisture and dirt, for example, coal dust or salt spray. This test method is an accelerated test that simulates extremely severe outdoor contamination. It is believed that the most severe conditions likely to be encountered in outdoor service in the United States will be relatively mild compared to the conditions specified in this test method.
6.2 Test Results—Materials can be classified by this test method as tracking-resistant, tracking-affected, or tracking-susceptible. The exact test values for these categories as they apply to specific uses will be specified in the appropriate material specifications, but guideline figures are suggested in Note 4. Tracking-resistant materials, unless erosion failure occurs first, have the potential to last many hundreds of hours (Note 5). Erosion, though it is possible that it will progress laterally, generally results in a failure perpendicular to the specimen surface. Therefore, compare only specimens of the same nominal thickness for resistance to tracking-induced erosion. Estimate the extent of erosion from measurements of the depth of penetration of the erosion. Place materials that are not tracking-susceptible in three broad categories—erosion-resistant, erosion-affected, and erosion-susceptible. When the standard thickness specimen is tested, the following times to failure typify the categories (Note 6):
Erosion-susceptible
5 to 50 h
Erosion-affected
50 to 200 h
Erosion-resistant
over 200 h
Note 4: Tracking-susceptible materials usually fail within 5 h. Tracking-affected materials usually fail before about 100 h.
Note 5: This information is derived fr...
SCOPE
1.1 This test method is intended to differentiate solid electrical insulating materials with respect to their resistance to the action of electric arcs produced by conduction through surface films of a specified contaminant containing moisture. Test Methods D2302 and D2303 are also useful to evaluate materials.
1.2 The values stated in inch-pound units are the standard, except in cases where SI units are more appropriate. The values in parentheses are for information only. Specific precautionary statements are given in 12.4.
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
Note 1: There is no equivalent ISO standard.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: D2132 − 12 (Reapproved 2018)
Standard Test Method for
Dust-and-Fog Tracking and Erosion Resistance of Electrical
Insulating Materials
This standard is issued under the fixed designation D2132; 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 Water-to-Metal Discharges (Withdrawn 1982)
D2303 Test Methods for Liquid-Contaminant, Inclined-
1.1 This test method is intended to differentiate solid elec-
Plane Tracking and Erosion of Insulating Materials
trical insulating materials with respect to their resistance to the
action of electric arcs produced by conduction through surface
3. Terminology
films of a specified contaminant containing moisture. Test
3.1 Definitions:
Methods D2302 and D2303 are also useful to evaluate mate-
3.1.1 For definitions pertinent to this test method see Ter-
rials.
minology D1711.
1.2 The values stated in inch-pound units are the standard,
4. High Voltage Hazard
exceptincaseswhereSIunitsaremoreappropriate.Thevalues
in parentheses are for information only. Specific precautionary
4.1 Lethal voltages are a potential hazard during the perfor-
statements are given in 12.4.
mance of this test. It is essential that the test apparatus, and all
associated equipment electrically connected to it, be properly
1.3 This standard does not purport to address all of the
designed and installed for safe operation.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4.2 Solidly ground all electrically conductive parts which it
priate safety, health, and environmental practices and deter-
is possible for a person to contact during the test.
mine the applicability of regulatory limitations prior to use.
4.3 Provide means for use at the completion of any test to
NOTE 1—There is no equivalent ISO standard. ground any parts which were at high voltage during the test or
have the potential for acquiring an induced charge during the
1.4 This international standard was developed in accor-
test or retaining a charge even after disconnection of the
dance with internationally recognized principles on standard-
voltage source.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4.4 Thoroughly instruct all operators as to the correct
mendations issued by the World Trade Organization Technical
procedures for performing tests safely.
Barriers to Trade (TBT) Committee.
4.5 When making high voltage tests, particularly in com-
pressed gas or in oil, it is possible for the energy released at
2. Referenced Documents
breakdown to be sufficient to result in fire, explosion, or
2.1 ASTM Standards: rupture of the test chamber. Design test equipment, test
D709 Specification for Laminated Thermosetting Materials chambers, and test specimens so as to minimize the possibility
D1711 Terminology Relating to Electrical Insulation of such occurrences and to eliminate the possibility of personal
D2302 Method of Test for Differential Wet Tracking Resis- injury.
tance of Electrical Insulating Materials with Controlled
NOTE 2—If the potential for fire exists, have fire suppression equipment
available.
5. Summary of Test Method
This test method is under the jurisdiction of ASTM Committee D09 on
Electrical and Electronic Insulating Materials and is the direct responsibility of
5.1 With electrodes mounted as shown in Fig. 1, coat test
Subcommittee D09.07 on Electrical Insulating Materials.
specimens with a synthetic dust and test in a chamber shown in
Current edition approved Nov. 1, 2018. Published November 2018. Originally
Fig. 2. Direct a water spray at the test specimen. After the
approved in 1962. Last previous edition approved in 2012 as D2132 – 12. DOI:
10.1520/D2132-18. surface has been wetted, apply a 60-Hz voltage between the
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2132 − 12 (2018)
5.3 Rate materials that do not track in terms of the time
required to erode to failure.
5.4 Failure will be indicated when the current increases
sufficiently to actuate an overcurrent device.
NOTE 3—The conditions of this test favor the formation of a track for
several possible reasons. Most important, the continuous renewal of the
conductingpropertiesofthecontaminantbythewatersprayallowsatrack
to grow progressively over long periods of time.
6. Significance and Use
6.1 Method—It is possible that electrical insulation in ser-
vice will fail as a result of tracking, erosion, or a combination
of both, if exposed to high relative humidity and contamination
environments.This is particularly true of organic insulations in
outdoor applications where the surface of the insulation be-
comes contaminated by deposits of moisture and dirt, for
example, coal dust or salt spray. This test method is an
accelerated test that simulates extremely severe outdoor con-
tamination. It is believed that the most severe conditions likely
to be encountered in outdoor service in the United States will
be relatively mild compared to the conditions specified in this
Metric Equivalents
test method.
1 1
in. ⁄8 ⁄2 12
mm 3.2 12.7 25.4 50.8
6.2 Test Results—Materials can be classified by this test
method as tracking-resistant, tracking-affected, or tracking-
FIG. 1 Test Arrangement of Electrode System
susceptible. The exact test values for these categories as they
apply to specific uses will be specified in the appropriate
material specifications, but guideline figures are suggested in
Note 4. Tracking-resistant materials, unless erosion failure
occurs first, have the potential to last many hundreds of hours
(Note 5). Erosion, though it is possible that it will progress
laterally, generally results in a failure perpendicular to the
specimen surface. Therefore, compare only specimens of the
same nominal thickness for resistance to tracking-induced
erosion. Estimate the extent of erosion from measurements of
the depth of penetration of the erosion. Place materials that are
not tracking-susceptible in three broad categories—erosion-
resistant, erosion-affected, and erosion-susceptible. When the
standard thickness specimen is tested, the following times to
failure typify the categories (Note 6):
Erosion-susceptible 5 to 50 h
18 in. = 458 mm 20 in. = 508 mm 28 in. = 712 mm
Erosion-affected 50 to 200 h
Erosion-resistant over 200 h
FIG. 2 Dust and Fog Test Chamber,
Minimum Recommended Size
NOTE 4—Tracking-susceptible materials usually fail within 5 h.
Tracking-affected materials usually fail before about 100 h.
NOTE5—Thisinformationisderivedfromtheindividualexperiencesof
electrodes.Arcingoccursacrosslocalizedhigh-resistanceareas
eight laboratories using this test method since its publication as a
produced by nonuniform evaporation of the water from the
suggested test method in June 1957, and from the results of an organized
contaminant. These arcs produce high temperatures in the
test program among these laboratories.
underlying insulation with resultant carbonization of most
NOTE 6—In a normal distribution approximately 68 % of all test values
organic materials. The carbonization concentrates the electric
are included within 61 standard deviation of the mean.
field. It is possible further carbonization will occur in the
6.3 Interpretation of Test Results—This test method pro-
direction of the field. In such cases, a carbon track is formed
vides information that allows classification as described in 6.2.
which spans the distance between the electrodes and causes
The comparison of materials within the same group is likely to
failure. It is possible that materials that do not track will erode
be ambiguous unless three or more replicate specimens are
under the action of the arcing. Such erosion usually progresses
tested.When the test method is used for specification purposes,
from an upper electrode through the thickness of the specimen
do not establish simple minimum values without consideration
towards the underlying electrode.
of the large variance to be expected in test results. It is
5.2 Rate materials that track in terms of the time required to recommended that quality levels and specification minima be
form a track between the electrodes. determined by statistical techniques.
D2132 − 12 (2018)
7. Apparatus 7.6 Monitoring Provisions—Use an ac ammeter, A, to moni-
tor specimen current. Use a separate ammeter for each test
7.1 General—Aschematic diagram of the power supply and
specimen.Alternatively make provisions to connect an amme-
control apparatus for testing one specimen is shown in Fig.
ter into each test-specimen circuit. Shunt the ammeter with a
3(a). It is generally desirable to test three or more specimens
normally closed contact, PB, and a capacitance, C, to protect
simultaneously. It is recommended but not mandatory that a
the ammeter from the large intermittent currents that occur
separate power supply and control be used for each test
during break-in. Connect the capacitance, if used, by a switch,
specimen. This allows “breaking-in” and recording of time to
S .After the break-in period, open the switch unless the values
A
failure separately for each specimen.
of the capacitance and ammeter impedances are such as to
7.2 Circuit Breaker—The circuit breaker (current relay, OL)
producenegligibleerrorincurrentmeasurement.Useterminals
interrupts the power supply on failure and stops the timing
A, B and C, D for oscilloscope monitoring, for current
meter. Use it as an ON-OFF switch and as a device for
measurement with a voltmeter in combination with a resistor,
interrupting air and water supply when all specimens fail. Fig.
or for insertion of an undercurrent relay to be used to stop the
3(b) illustrates the air and water supply circuit when three
clock if the scintillation current falls below the specified value.
specimens are tested using one fog nozzle. The circuit breaker
7.7 Electrodes—Use three copper or brass electrodes ⁄2 by
shall be rated at 2 to 3 A, inverse-time element type, for a
2by ⁄8 in. (13 by 51 by 3.2 mm), with corners rounded to a
115-V supply. Use a resistance, R , to shunt the current coil
⁄8-in. (3.2-mm) radius on the top surface of the specimen and
during the break-in period so that the breaker will not actuate
spaced 1 in. (25 mm) apart as shown in Fig. 1. Use a ground
as a result of the bright-flash currents typical of this period.
plate of copper or brass and of the same size as the test
Adjust the resistance to produce an effective breaker action at
specimen on the bottom surface and mounted on an insulating
approximately 6 A (115-V supply). Remove or switch out the
support inclined 15 deg to the horizontal as shown in Fig. 1.
shunt resistance after break-in.
Clamp the electrodes firmly to the test specimen. A suggested
7.3 Supply Transformer —Use a supply transformer, T ,
arrangement is shown in Fig. 4.
capable of supplying 1500 V, 60 Hz, rms. A200-VA potential
7.8 Test Chamber—Use a cubicle test chamber, Fig. 2, made
transformer is capable of supplying power for up to three
from plastic or metal. The front wall is made of glass or
specimens if desired. Use a transformer with a 20:1 ratio when
poly(methyl methacrylate), or contains viewing ports or doors
used with a 115-V primary supply. Choose a transformer that
made of these materials. Make the cubicle at least 20 in. (510
offers an impedance between 600 and 1200Ω resistance and
mm) high and 28 in. (710 mm) wide. Determine the depth by
200 and 700 Ω reactance. Accomplish this by insertion of
the number of specimens to be tested. Three specimens require
inductance L and resistance R in the low-voltage side and
a minimum depth of 18 in. (460 mm). Fit the chamber with
resistance R in the high-voltage side.
means for venting near the bottom of the cubicle, preferably
7.4 Control Transformer—Use a variable-ratio
along the end of the chamber where the specimens are located.
2 2
autotransformer, T , to adjust the voltage as required.
Limit the venting area to about 20 in. (130 cm ) to eliminate
7.5 Voltmeter—Use a voltmeter, V, in the primary side to dependence of test results on the ambient humidity.
7.8.1 Mount one or more fog nozzles (Fig. 5) to obtain the
determine the specimen test voltage. Alternatively, use a
high-impedance voltmeter for connection in the secondary, in specified uniform moisture deposition on all test specimens. It
is suggested that one fog nozzle, mounted approximately 25 in.
which case take precautions to prevent electric shock to an
operator. If a voltmeter is used in the primary, calibrate it (635 mm) straight line distance from the nozzle to the center
specimen at a height of approximately 14 in. (355 mm) above
against secondary voltage with a secondary load of 10 mA.
these specimens, will, with a suitably adjusted deflector,
produce the specified conditions for three test specimens in a
General Electric Type JE41, Model KAR-3, and Westinghouse Type VS, Style
single cubicle (see Fig. 2). When only one fog nozzle is used
No. 687588, have been found satisfactory for this purpose.
in the cubicle, it is recommended that additional air be
introduced into the cubicle equal to about double that flowing
through a standard fog nozzle connected to an air supply of 5
to 6 psig (34 to 41 kPa).
7.8.2 Connect the fog nozzle assembly, Fig. 6 , to an air and
water supply. Provide means to adjust the air supply to 5 to 6
psig (0.035-0.04 MPa). Supply the water from a reservoir
mounted below the nozzle so that the water level is approxi-
mately 5 in. (125 mm) below the nozzle. Use a needle valve in
thewaterlinetothenozzletocontroltherateoffogdeposition.
To ensure uninterrupted flow of the water to the nozzle, filter
the water to remove the dissolved air in the water.
(a) Power supply and control circuit of wet tracking tests.
A suitable fog nozzle is a Lucite atomizer, Model 145-718 manufactured by
(b) Air and water supply circuit.
Industrial Filter and Pump Manufacturing Co., 5916 Ogden Ave., Chicago, IL
FIG. 3 Circuit Diagrams 60650.(708-656-7800)
D2132 − 12 (20
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D2132 − 12 D2132 − 12 (Reapproved 2018)
Standard Test Method for
Dust-and-Fog Tracking and Erosion Resistance of Electrical
Insulating Materials
This standard is issued under the fixed designation D2132; 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
1.1 This test method is intended to differentiate solid electrical insulating materials with respect to their resistance to the action
of electric arcs produced by conduction through surface films of a specified contaminant containing moisture. Test Methods D2302
and D2303 are also useful to evaluate materials.
1.2 The values stated in inch-pound units are the standard, except in cases where SI units are more appropriate. The values in
parentheses are for information only. Specific precautionary statements are given in 12.4.
1.3 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.Specific precautionary statements are given in 12.4.
NOTE 1—There is no equivalent ISO standard.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D709 Specification for Laminated Thermosetting Materials
D1711 Terminology Relating to Electrical Insulation
D2302 Method of Test for Differential Wet Tracking Resistance of Electrical Insulating Materials with Controlled Water-to-
Metal Discharges (Withdrawn 1982)
D2303 Test Methods for Liquid-Contaminant, Inclined-Plane Tracking and Erosion of Insulating Materials
3. Terminology
3.1 Definitions:
3.1.1 For definitions pertinent to this test method see Terminology D1711.
4. High Voltage Hazard
4.1 Lethal voltages are a potential hazard during the performance of this test. It is essential that the test apparatus, and all
associated equipment electrically connected to it, be properly designed and installed for safe operation.
4.2 Solidly ground all electrically conductive parts which it is possible for a person to contact during the test.
4.3 Provide means for use at the completion of any test to ground any parts which were at high voltage during the test or have
the potential for acquiring an induced charge during the test or retaining a charge even after disconnection of the voltage source.
4.4 Thoroughly instruct all operators as to the correct procedures for performing tests safely.
This test method is under the jurisdiction of ASTM Committee D09 on Electrical and Electronic Insulating Materials and is the direct responsibility of Subcommittee
D09.07 on Electrical Insulating Materials.
Current edition approved Jan. 1, 2012Nov. 1, 2018. Published February 2012November 2018. Originally approved in 1962. Last previous edition approved in 20112012
as D2132 – 11.D2132 – 12. DOI: 10.1520/D2132-12.10.1520/D2132-18.
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 ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2132 − 12 (2018)
4.5 When making high voltage tests, particularly in compressed gas or in oil, it is possible for the energy released at breakdown
to be sufficient to result in fire, explosion, or rupture of the test chamber. Design test equipment, test chambers, and test specimens
so as to minimize the possibility of such occurrences and to eliminate the possibility of personal injury.
NOTE 2—If the potential for fire exists, have fire suppression equipment available.
5. Summary of Test Method
5.1 With electrodes mounted as shown in Fig. 1, coat test specimens with a synthetic dust and test in a chamber shown in Fig.
2. Direct a water spray at the test specimen. After the surface has been wetted, apply a 60-Hz voltage between the electrodes.
Arcing occurs across localized high-resistance areas produced by nonuniform evaporation of the water from the contaminant.
These arcs produce high temperatures in the underlying insulation with resultant carbonization of most organic materials. The
carbonization concentrates the electric field. It is possible further carbonization will occur in the direction of the field. In such cases,
a carbon track is formed which spans the distance between the electrodes and causes failure. It is possible that materials that do
not track will erode under the action of the arcing. Such erosion usually progresses from an upper electrode through the thickness
of the specimen towards the underlying electrode.
5.2 Rate materials that track in terms of the time required to form a track between the electrodes.
5.3 Rate materials that do not track in terms of the time required to erode to failure.
5.4 Failure will be indicated when the current increases sufficiently to actuate an overcurrent device.
NOTE 3—The conditions of this test favor the formation of a track for several possible reasons. Most important, the continuous renewal of the
conducting properties of the contaminant by the water spray allows a track to grow progressively over long periods of time.
6. Significance and Use
6.1 Method—It is possible that electrical insulation in service will fail as a result of tracking, erosion, or a combination of both,
if exposed to high relative humidity and contamination environments. This is particularly true of organic insulations in outdoor
applications where the surface of the insulation becomes contaminated by deposits of moisture and dirt, for example, coal dust or
salt spray. This test method is an accelerated test that simulates extremely severe outdoor contamination. It is believed that the most
severe conditions likely to be encountered in outdoor service in the United States will be relatively mild compared to the conditions
specified in this test method.
6.2 Test Results—Materials can be classified by this test method as tracking-resistant, tracking-affected, or tracking-susceptible.
The exact test values for these categories as they apply to specific uses will be specified in the appropriate material specifications,
but guideline figures are suggested in Note 4. Tracking-resistant materials, unless erosion failure occurs first, have the potential
Metric Equivalents
1 1
in. ⁄8 ⁄2 1 2
mm 3.2 12.7 25.4 50.8
FIG. 1 Test Arrangement of Electrode System
D2132 − 12 (2018)
18 in. = 458 mm 20 in. = 508 mm 28 in. = 712 mm
FIG. 2 Dust and Fog Test Chamber,
Minimum Recommended Size
to last many hundreds of hours (Note 5). Erosion, though it is possible that it will progress laterally, generally results in a failure
perpendicular to the specimen surface. Therefore, compare only specimens of the same nominal thickness for resistance to
tracking-induced erosion. Estimate the extent of erosion from measurements of the depth of penetration of the erosion. Place
materials that are not tracking-susceptible in three broad categories—erosion-resistant, erosion-affected, and erosion-susceptible.
When the standard thickness specimen is tested, the following times to failure typify the categories (Note 6):
Erosion-susceptible 5 to 50 h
Erosion-affected 50 to 200 h
Erosion-resistant over 200 h
NOTE 4—Tracking-susceptible materials usually fail within 5 h. Tracking-affected materials usually fail before about 100 h.
NOTE 5—This information is derived from the individual experiences of eight laboratories using this test method since its publication as a suggested
test method in June 1957, and from the results of an organized test program among these laboratories.
NOTE 6—In a normal distribution approximately 68 % of all test values are included within 61 standard deviation of the mean.
6.3 Interpretation of Test Results—This test method provides information that allows classification as described in 6.2. The
comparison of materials within the same group is likely to be ambiguous unless three or more replicate specimens are tested. When
the test method is used for specification purposes, do not establish simple minimum values without consideration of the large
variance to be expected in test results. It is recommended that quality levels and specification minima be determined by statistical
techniques.
7. Apparatus
7.1 General—A schematic diagram of the power supply and control apparatus for testing one specimen is shown in Fig. 3(a).
It is generally desirable to test three or more specimens simultaneously. It is recommended but not mandatory that a separate power
supply and control be used for each test specimen. This allows “breaking-in” and recording of time to failure separately for each
specimen.
(a) Power supply and control circuit of wet tracking tests.
(b) Air and water supply circuit.
FIG. 3 Circuit Diagrams
D2132 − 12 (2018)
7.2 Circuit Breaker—The circuit breaker (current relay, OL) interrupts the power supply on failure and stops the timing meter.
Use it as an ON-OFF switch and as a device for interrupting air and water supply when all specimens fail. Fig. 3(b) illustrates the
air and water supply circuit when three specimens are tested using one fog nozzle. The circuit breaker shall be rated at 2 to 3 A,
inverse-time element type, for a 115-V supply. Use a resistance, R , to shunt the current coil during the break-in period so that the
breaker will not actuate as a result of the bright-flash currents typical of this period. Adjust the resistance to produce an effective
breaker action at approximately 6 A (115-V supply). Remove or switch out the shunt resistance after break-in.
7.3 Supply Transformer —Use a supply transformer, T , capable of supplying 1500 V, 60 Hz, rms. A200-VA potential
transformer is capable of supplying power for up to three specimens if desired. Use a transformer with a 20:1 ratio when used with
a 115-V primary supply. Choose a transformer that offers an impedance between 600 and 1200 Ω resistance and 200 and 700 Ω
reactance. Accomplish this by insertion of inductance L and resistance R in the low-voltage side and resistance R in the
1 2
high-voltage side.
7.4 Control Transformer—Use a variable-ratio autotransformer, T , to adjust the voltage as required.
7.5 Voltmeter—Use a voltmeter, V, in the primary side to determine the specimen test voltage. Alternatively, use a
high-impedance voltmeter for connection in the secondary, in which case take precautions to prevent electric shock to an operator.
If a voltmeter is used in the primary, calibrate it against secondary voltage with a secondary load of 10 mA.
7.6 Monitoring Provisions—Use an ac ammeter, A, to monitor specimen current. Use a separate ammeter for each test specimen.
Alternatively make provisions to connect an ammeter into each test-specimen circuit. Shunt the ammeter with a normally closed
contact, PB, and a capacitance, C, to protect the ammeter from the large intermittent currents that occur during break-in. Connect
the capacitance, if used, by a switch, S . After the break-in period, open the switch unless the values of the capacitance and
A
ammeter impedances are such as to produce negligible error in current measurement. Use terminals A,B and C,D for oscilloscope
monitoring, for current measurement with a voltmeter in combination with a resistor, or for insertion of an undercurrent relay to
be used to stop the clock if the scintillation current falls below the specified value.
1 1 1
7.7 Electrodes—Use three copper or brass electrodes ⁄2 by 2 by ⁄8 in. (13 by 51 by 3.2 mm), with corners rounded to a ⁄8-in.
(3.2-mm) radius on the top surface of the specimen and spaced 1 in. (25 mm) apart as shown in Fig. 1. Use a ground plate of copper
or brass and of the same size as the test specimen on the bottom surface and mounted on an insulating support inclined 15 deg
to the horizontal as shown in Fig. 1. Clamp the electrodes firmly to the test specimen. A suggested arrangement is shown in Fig.
4.
7.8 Test Chamber—Use a cubicle test chamber, Fig. 2, made from plastic or metal. The front wall is made of glass or
poly(methyl methacrylate), or contains viewing ports or doors made of these materials. Make the cubicle at least 20 in. (510 mm)
high and 28 in. (710 mm) wide. Determine the depth by the number of specimens to be tested. Three specimens require a minimum
FIG. 4 Clamping Arrangement for Test-Specimen Electrodes
General Electric Type JE41, Model KAR-3, and Westinghouse Type VS, Style No. 687588, have been found satisfactory for this purpose.
D2132 − 12 (2018)
depth of 18 in. (460 mm). Fit the chamber with means for venting near the bottom of the cubicle, preferably along the end of the
2 2
chamber where the specimens are located. Limit the venting area to about 20 in. (130 cm ) to eliminate dependence of test results
on the ambient humidity.
7.8.1 Mount one or more fog nozzles (Fig. 5) to obtain the specified uniform moisture deposition on all test specimens. It is
suggested that one fog nozzle, mounted approximately 25 in. (635 mm) straight line distance from the nozzle to the center
specimen at a height of approximately 14 in. (355 mm) above these specimens, will, with a suitably adjusted deflector, produce
the specified conditions for three test specimens in a single cubicle (see Fig. 2). When only one fog nozzle is used in the cubicle,
it is recommended that additional air be introduced into the cubicle equal to about double that flowing through a standard fog
nozzle connected to an air supply of 5 to 6 psig (34 to 41 kPa).
7.8.2 Connect the fog nozzle assembly, Fig. 6 , to an air and water supply. Provide
...
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