ASTM F479-06(2017)
(Specification)Standard Specification for In-Service Care of Insulating Blankets
Standard Specification for In-Service Care of Insulating Blankets
ABSTRACT
This specification covers elastomeric seals (gaskets) used to seal the joints of plastic pipe used for gravity, low-pressure, and high-pressure applications. This refers to push-on joints which require no internal or external pressure to effect the initial seal. Tensile strength, elongation, hardness, compression set, accelerated aging, water immersion, ozone resistance, and force decay shall be tested to meet the requirements prescribed.This specification covers the in-service care, inspection, testing, and use voltage of insulating blankets for protection of workers from accidental contact with live electrical conductors, apparatus, or circuits. Blankets covered shall be designated as type I or type II; class 0, class 1, class 2, class 3, or class 4; style A or style B: type I - not resistant to ozone, made from a high-grade cis-1,4-polyisoprene rubber compound of natural or synthetic origin, properly vulcanized; and type II - ozone-resistant, made of any elastomer or combination of elastomeric compounds. Style A - constructed of the elastomers indicated under type I or type II, shall be free of any reinforcement; and style B - constructed of the elastomers indicated under type I or type II, shall incorporate a reinforcement. Electrical testing shall be performed to meet the requirements prescribed.
SCOPE
1.1 This specification covers the in-service care, inspection, testing, and use voltage of insulating blankets for protection of workers from accidental contact with live electrical conductors, apparatus, or circuits. The product requirements and acceptance testing are as shown in Specification D1048.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
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.See Section 6 and 8.2 for specific precautionary statements.
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:F479 −06 (Reapproved 2017)
Standard Specification for
In-Service Care of Insulating Blankets
ThisstandardisissuedunderthefixeddesignationF479;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope C84.1 Voltage Ratings for Electric Power Systems and
Equipment (60 Hz)
1.1 This specification covers the in-service care, inspection,
testing, and use voltage of insulating blankets for protection of
3. Terminology
workers from accidental contact with live electrical
3.1 Definitions:
conductors, apparatus, or circuits. The product requirements
3.1.1 breakdown—the electrical discharge or arc occurring
and acceptance testing are as shown in Specification D1048.
betweentheelectrodesandthroughtheequipmentbeingtested.
1.2 The values stated in inch-pound units are to be regarded
3.1.2 compatible—not injurious to or changing the physical
as standard. The values given in parentheses are mathematical
or electrical characteristics of the blankets or affecting their
conversions to SI units that are provided for information only
application, use, or acceptability.
and are not considered standard.
3.1.3 designated person—an individual who is qualified by
1.3 This standard does not purport to address all of the
experience or training to perform an assigned task.
safety concerns, if any, associated with its use. It is the
3.1.4 electrical testing facility—a location with qualified
responsibility of the user of this standard to establish appro-
personnel,testingequipment,andproceduresfortheinspection
priate safety, health, and environmental practices and deter-
and electrical testing of electrical insulating protective equip-
mine the applicability of regulatory limitations prior to use.See
ment.
Section 6 and 8.2 for specific precautionary statements.
3.1.5 electrode—the energized or grounded conductor por-
1.4 This international standard was developed in accor-
tion of electrical test equipment which is placed near or in
dance with internationally recognized principles on standard-
contact with the material or equipment being tested.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3.1.6 flashover—the electrical discharge or arc occurring
mendations issued by the World Trade Organization Technical
between electrodes and over or around, but not through, the
Barriers to Trade (TBT) Committee.
equipment being tested.
3.1.7 insulated—separated from other conducting surfaces
2. Referenced Documents
by a dielectric substance (including air space) offering a high
2.1 ASTM Standards:
resistance to the passage of current.
D1048 Specification for Rubber Insulating Blankets
3.1.7.1 Discussion—Whenanyobjectissaidtobeinsulated,
D2865 Practice for Calibration of Standards and Equipment
it is understood to be insulated in a suitable manner for the
for Electrical Insulating Materials Testing
conditions to which it is subjected. Otherwise, it is, within the
F819 Terminology Relating to Electrical Protective Equip-
purposes of this definitions, uninsulated. Insulating covering of
ment for Workers
conductors is one means of making the conductor insulated.
2.2 ANSI Standard:
3.1.8 ozone—a very active form of oxygen that may be
C39.5 Safety Requirements for Electrical and Electronic
produced by corona, arcing, or ultraviolet rays.
Measuring and Controlling Instrumentation
3.1.9 ozone cutting and checking—the cracks produced by
ozone in a material under mechanical stress.
This specification is under the jurisdiction of ASTM Committee F18 on
Electrical Protective Equipment for Workers and is the direct responsibility of
3.1.10 retest—the tests given after the initial acceptance test
Subcommittee F18.25 on Insulating Cover-Up Equipment.
usually performed at regular periodic intervals or as required
Current edition approved Dec. 15, 2017. Published January 2018. Originally
approved in 1976. Last previous edition approved in 2011 as F479–06(2011). DOI:
because of physical inspection.
10.1520/F0479-06R17.
3.1.11 unassigned blankets—blankets that are in storage
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
prior to being issued for use.
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
3.1.12 voltage, maximum use—the ac voltage (rms), classi-
the ASTM website.
3 fication of the protective equipment that designates the maxi-
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. mum nominal design voltage of the energized system that may
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F479−06 (2017)
be safely worked. The nominal design voltage is equal to the 6. Safety Precautions
phase-to-phase voltage on multiphase circuits.
6.1 A margin of safety shall be provided between the
3.1.12.1 Discussion—If there is no multiphase exposure in a
maximum use voltage on which the blankets are used and the
system area, and the voltage exposure is limited to the phase
voltage at which they are retested. The relationship between
(polarityondcsystems)togroundpotential,thephase(polarity
retest voltage and maximum use voltage at which the blankets
ondcsystems)togroundpotentialshallbeconsideredtobethe
shall be used is shown in Table 1.
nominal design voltage.
6.2 The user of this type of protective equipment shall be
3.1.12.2 Discussion—If electrical equipment and devices
knowledgeable of and instructed in the correct and safe visual
are insulated or isolated, or both, such that the multiphase
inspection and use of this equipment.
exposure on a grounded wye circuit is removed, then the
nominal design voltage may be considered as the phase-to-
7. Inspection and Testing at an Electrical Testing Facility
ground voltage on that circuit.
7.1 The recommended sequence for inspection and testing
3.1.12.3 Discussion—The work practices and methods as-
of insulating blankets at the electrical testing facility is as
sociated with removing multiphase exposures at any given
follows:
work site are not addressed in the ASTM standards. The users
7.1.1 Check in, washing, and preliminary inspection,
of ASTM standards should reference appropriate industry
7.1.2 Electrical test,
consensus standards for proper work practices.
7.1.3 Final inspection,
3.1.13 voltage, maximum retest—the voltage, either ac rms 7.1.4 Recordkeeping and marking, and
or dc avg, that is equal to the proof test voltage for new 7.1.5 Packing for storage and shipping.
protective equipment.
7.2 Dirty blankets should be cleaned. They may be washed
with a mild soap or mild detergent and water. Mild household-
3.1.14 voltage, nominal design—a nominal value consistent
type chlorine bleach may be used for disinfectant purposes.
with ANSI C84.1-2001, assigned to the circuit or system for
Soaps, detergents, and bleaches shall not be used at strengths
the purpose of conveniently designating its voltage class.
that would attack or harm the rubber surface. They shall be
3.1.15 voltage, retest—the voltage, either ac rms or dc avg,
rinsed thoroughly with water to remove all of the soap or
that used protective equipment must be capable of withstand-
detergent. Severe dirt and grime may be wiped off using a
ing for a specified test period without breakdown.
compatible solvent.
3.2 For definitions of other terms, refer to Terminology 7.2.1 The cleaning agent shall not degrade the insulating or
F819. physical qualities of the blankets.
7.2.2 A commercial tumble type washing machine may be
4. Significance and Use used. Caution must be observed to eliminate any interior
surfaces or edges that may damage the blankets.
4.1 Compliance with this specification should continue to
7.3 Ifwashed,blanketsshouldbeair-dried.Theairtempera-
provide personnel with insulating blankets of known and
ture should not be over 150°F (65.5°C).
acceptable quality after initial acceptance in accordance with
Specification D1048.The standards herein are to be considered
7.4 Prior to the electrical test, the blankets shall be given a
as minimum requirements.
preliminary inspection for punctures, cuts, corona cutting, or
any obvious condition which would adversely affect the
5. Classification
performance. If any of these conditions are found, blankets
shall be rejected or repaired.
5.1 Blankets covered under this specification shall be des-
ignated as Type I or Type II; Class 0, Class 1, Class 2, Class 3, 7.5 The blankets shall be tested in accordance with Section
8.
or Class 4; Style A or Style B.
5.2 Type I, not resistant to ozone, made from a high-grade
cis-1,4-polyisoprene rubber compound of natural or synthetic
TABLE 1 Voltage Requirements for Blankets
origin, properly vulcanized.
Class AC Use AC Retest DC Retest
Designation of Voltage, Voltage, Voltage,
5.3 Type II, ozone-resistant, made of any elastomer or
A
Blankets rms, max max max
combination of elastomeric compounds.
0 1000 5000 20 000
1 7500 10 000 40 000
5.4 The class designation shall be based on the electrical
2 17 000 20 000 50 000
properties as shown in Specification D1048. 3 26 500 30 000 60 000
4 36 000 40 000 70 000
5.5 Style A, constructed of the elastomers indicated under
A
The maximum use voltage is based on the following equations:
Type I or Type II, shall be free of any reinforcement.
Maximum ac use voltage = 0.95 ac maximum retest voltage − 2 000
v
Classes 1, 2, 3, and 4.
5.6 Style B, constructed of the elastomers indicated under Maximum ac use voltage = 0.95 dc maximum retest voltage − 30 500
v
Classes 1, 2, 3, and 4.
Type I or Type II, shall incorporate a reinforcement. This
Maximum ac use voltage = 0.95 dc maximum retest voltage − 18 000
v
reinforcement shall not affect adversely the dielectric charac-
Class 0.
teristics of the blankets.
F479−06 (2017)
7.6 After the test, the blankets shall be given an inspection 8.5.1.1 A voltmeter used in conjunction with a calibrated
for corona and ozone damage. instrument transformer connected directly across the high
voltage circuit,
8. Electrical Tests
8.5.1.2 A calibrated electrostatic voltmeter connected di-
8.1 All blankets issued for service shall be retested and shall
rectly across the high voltage circuit, or
withstand the 60-Hz ac test voltage (rms value) or the dc
8.5.1.3 An ac meter connected in series with appropriate
voltage (average value) specified in Table 1.The retest shall be
high-voltage type resistors directly across the high voltage
performedinaccordancewithSection8andshallbeconducted
circuit.
continuously for not less than 1 min, and not more than 3 min.
8.5.1.4 Thecrestfactormaybecheckedbytheuseofapeak
8.1.1 The interval between date of issue and retests shall be
reading voltmeter connected directly across the high-voltage
based on work practices and test experience, but shall not
circuit.
exceed 1 year. Blankets that have been tested electrically, but
8.5.2 AC Retest:
not issued for service, shall not be placed into service unless
8.5.2.1 Each blanket shall be given an electrical retest in
they have been tested electrically within the previous 12
accordance with 8.1. The test period shall start at the instant
months.
that the prescribed testing voltage is reached.
8.1.2 Where a visual inspection indicates that there may be
NOTE 2—It is recommended that the retest voltage be applied initially
reason to suspect the electrical integrity of a blanket, an
at a low value and increased at a constant rate-of-rise of approximately
electrical test shall be performed before reissuing the blanket
1000 V/s until the prescribed test voltage level is reached. Unless an
for service.
electrical puncture has already occurred, the applied voltage should be
reduced to at least half value at the end of the test period before opening
8.2 The test apparatus shall be designed to afford the
the test circuit.
operator full protection in the performance of his duties.
8.5.2.2 Electrodes shall be of such design so as to apply the
Reliable means of de-energizing and grounding the high
electricalstressuniformlyoverthetestareatominimizecorona
voltage circuit shall be provided. It is particularly important to
and mechanical strain in the material. The electrodes used in
incorporate positive means of grounding the high voltage
the proof test shall be designed to comply with the flashover
section of dc test apparatus due to the likely presence of
clearances specified in Table 2.
high-voltage capacitance charges at the conclusion of the test.
See ANSI C39.5.
NOTE 3—Recommended Electrodes for Classes 0, 1, and
8.2.1 To eliminate damaging ozone and possible flashover 2—Rectangular metal sheets approximately ⁄16 in. (2 mm) thick having
edges and corners rounded smoothly and wet pads approximately ⁄4 in. (6
along the blanket, there should be a sufficient flow of air into
mm) thick, placed between the metal sheets and the blanket.
and around the blanket and an exhaust system to adequately
Recommended Electrodes for Classes 3 and 4—Maximum area can be
remove ozone from the test machine. Consistent ozone cutting
tested when both electrodes are the same size. When an insulated table is
and checking during the test procedure should be cause to
not convenient, the following mask method may be used. A 0.12 to 0.18
in. (3 to 5 mm) thick sheet of insulating material which is a minimum of
ascertain the adequacy of the exhaust system.
2 2
50 in. (1270 mm ) and has a 30 by 30 in. (762 by 762 mm) opening in
8.2.2 The equipment shall be inspected at least annually to
the center, is placed on a grounded metal plate. This mask which has a
ensurethatthegeneralconditionoftheequipmentisacceptable
“pictureframe”appearanceshallhavetheopeningfilledwithaconductive
and to verify the characteristics and accuracy of the test
material of such thickness as to bring the ground electrode to approxi-
voltages. To ensure the continued accuracy of the test voltage, mately the same level as the mask in order to maintain direct contact with
the blanket to be tested. The blanket is placed over the ground electrode,
asindicatedbythetestequipmentvoltmeter,thetestequipment
and a wet pad approximately the same size as the ground electrode, is
shall be calibrated at least annually, in accordance with the
placed on top of the blanket. The wet pad is energized with the test
latest revision of Practice D2865.
voltage. This method will test a 30 by 30 in. (762 by 762 mm
...
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: F479 − 06 (Reapproved 2011) F479 − 06 (Reapproved 2017)
Standard Specification for
In-Service Care of Insulating Blankets
This standard is issued under the fixed designation F479; 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 specification covers the in-service care, inspection, testing, and use voltage of insulating blankets for protection of
workers from accidental contact with live electrical conductors, apparatus, or circuits. The product requirements and acceptance
testing are as shown in Specification D1048.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.3 This standard does not purport to address all of the safety problems,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.See Section 6 and 8.2 for specific precautionary statements.
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:
D1048 Specification for Rubber Insulating Blankets
D2865 Practice for Calibration of Standards and Equipment for Electrical Insulating Materials Testing
F819 Terminology Relating to Electrical Protective Equipment for Workers
2.2 ANSI Standard:
C39.5 Safety Requirements for Electrical and Electronic Measuring and Controlling Instrumentation
C84.1 Voltage Ratings for Electric Power Systems and Equipment (60 Hz)
3. Terminology
3.1 Definitions:
3.1.1 breakdown—the electrical discharge or arc occurring between the electrodes and through the equipment being tested.
3.1.2 compatible—not injurious to or changing the physical or electrical characteristics of the blankets or affecting their
application, use, or acceptability.
3.1.3 designated person—an individual who is qualified by experience or training to perform an assigned task.
3.1.4 electrical testing facility—a location with qualified personnel, testing equipment, and procedures for the inspection and
electrical testing of electrical insulating protective equipment.
3.1.5 electrode—the energized or grounded conductor portion of electrical test equipment which is placed near or in contact with
the material or equipment being tested.
3.1.6 flashover—the electrical discharge or arc occurring between electrodes and over or around, but not through, the equipment
being tested.
This specification is under the jurisdiction of ASTM Committee F18 on Electrical Protective Equipment for Workers and is the direct responsibility of Subcommittee
F18.25 on Insulating Cover-Up Equipment.
Current edition approved Dec. 1, 2011Dec. 15, 2017. Published January 2012January 2018. Originally approved in 1976. Last previous edition approved in 20062011 as
F479F479–06(2011).–06. DOI: 10.1520/F0479-06R11.10.1520/F0479-06R17.
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.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F479 − 06 (2017)
3.1.7 insulated—separated from other conducting surfaces by a dielectric substance (including air space) offering a high
resistance to the passage of current.
3.1.7.1 Discussion—
When any object is said to be insulated, it is understood to be insulated in a suitable manner for the conditions to which it is
subjected. Otherwise, it is, within the purposes of this definitions, uninsulated. Insulating covering of conductors is one means of
making the conductor insulated.
3.1.8 ozone—a very active form of oxygen that may be produced by corona, arcing, or ultraviolet rays.
3.1.9 ozone cutting and checking—the cracks produced by ozone in a material under mechanical stress.
3.1.10 retest—the tests given after the initial acceptance test usually performed at regular periodic intervals or as required
because of physical inspection.
3.1.11 unassigned blankets—blankets that are in storage prior to being issued for use.
3.1.12 voltage, maximum use—the ac voltage (rms), classification of the protective equipment that designates the maximum
nominal design voltage of the energized system that may be safely worked. The nominal design voltage is equal to the
phase-to-phase voltage on multiphase circuits.
3.1.12.1 Discussion—
If there is no multiphase exposure in a system area, and the voltage exposure is limited to the phase (polarity on dc systems) to
ground potential, the phase (polarity on dc systems) to ground potential shall be considered to be the nominal design voltage.
3.1.12.2 Discussion—
If electrical equipment and devices are insulated or isolated, or both, such that the multiphase exposure on a grounded wye circuit
is removed, then the nominal design voltage may be considered as the phase-to-ground voltage on that circuit.
3.1.12.3 Discussion—
The work practices and methods associated with removing multiphase exposures at any given work site are not addressed in the
ASTM standards. The users of ASTM standards should reference appropriate industry consensus standards for proper work
practices.
3.1.13 voltage, maximum retest—the voltage, either ac rms or dc avg, that is equal to the proof test voltage for new protective
equipment.
3.1.14 voltage, nominal design—a nominal value consistent with ANSI C84.1-2001, assigned to the circuit or system for the
purpose of conveniently designating its voltage class.
3.1.15 voltage, retest—the voltage, either ac rms or dc avg, that used protective equipment must be capable of withstanding for
a specified test period without breakdown.
3.2 For definitions of other terms, refer to Terminology F819.
4. Significance and Use
4.1 Compliance with this specification should continue to provide personnel with insulating blankets of known and acceptable
quality after initial acceptance in accordance with Specification D1048. The standards herein are to be considered as minimum
requirements.
5. Classification
5.1 Blankets covered under this specification shall be designated as Type I or Type II; Class 0, Class 1, Class 2, Class 3, or Class
4; Style A or Style B.
5.2 Type I, not resistant to ozone, made from a high-grade cis-1,4-polyisoprene rubber compound of natural or synthetic origin,
properly vulcanized.
5.3 Type II, ozone-resistant, made of any elastomer or combination of elastomeric compounds.
5.4 The class designation shall be based on the electrical properties as shown in Specification D1048.
5.5 Style A, constructed of the elastomers indicated under Type I or Type II, shall be free of any reinforcement.
F479 − 06 (2017)
5.6 Style B, constructed of the elastomers indicated under Type I or Type II, shall incorporate a reinforcement. This
reinforcement shall not affect adversely the dielectric characteristics of the blankets.
6. Safety Precautions
6.1 A margin of safety shall be provided between the maximum use voltage on which the blankets are used and the voltage at
which they are retested. The relationship between retest voltage and maximum use voltage at which the blankets shall be used is
shown in Table 1.
6.2 The user of this type of protective equipment shall be knowledgeable of and instructed in the correct and safe visual
inspection and use of this equipment.
7. Inspection and Testing at an Electrical Testing Facility
7.1 The recommended sequence for inspection and testing of insulating blankets at the electrical testing facility is as follows:
7.1.1 Check in, washing, and preliminary inspection,
7.1.2 Electrical test,
7.1.3 Final inspection,
7.1.4 Recordkeeping and marking, and
7.1.5 Packing for storage and shipping.
7.2 Dirty blankets should be cleaned. They may be washed with a mild soap or mild detergent and water. Mild household-type
chlorine bleach may be used for disinfectant purposes. Soaps, detergents, and bleaches shall not be used at strengths that would
attack or harm the rubber surface. They shall be rinsed thoroughly with water to remove all of the soap or detergent. Severe dirt
and grime may be wiped off using a compatible solvent.
7.2.1 The cleaning agent shall not degrade the insulating or physical qualities of the blankets.
7.2.2 A commercial tumble type washing machine may be used. Caution must be observed to eliminate any interior surfaces
or edges that may damage the blankets.
7.3 If washed, blankets should be air-dried. The air temperature should not be over 150°F (65.5°C).
7.4 Prior to the electrical test, the blankets shall be given a preliminary inspection for punctures, cuts, corona cutting, or any
obvious condition which would adversely affect the performance. If any of these conditions are found, blankets shall be rejected
or repaired.
7.5 The blankets shall be tested in accordance with Section 8.
7.6 After the test, the blankets shall be given an inspection for corona and ozone damage.
8. Electrical Tests
8.1 All blankets issued for service shall be retested and shall withstand the 60-Hz ac test voltage (rms value) or the dc voltage
(average value) specified in Table 1. The retest shall be performed in accordance with Section 8 and shall be conducted
continuously for not less than 1 min, and not more than 3 min.
8.1.1 The interval between date of issue and retests shall be based on work practices and test experience, but shall not exceed
1 year. Blankets that have been tested electrically, but not issued for service, shall not be placed into service unless they have been
tested electrically within the previous 12 months.
8.1.2 Where a visual inspection indicates that there may be reason to suspect the electrical integrity of a blanket, an electrical
test shall be performed before reissuing the blanket for service.
TABLE 1 Voltage Requirements for Blankets
Class AC Use AC Retest DC Retest
Designation of Voltage, Voltage, Voltage,
A
Blankets rms, max max max
0 1000 5000 20 000
1 7500 10 000 40 000
2 17 000 20 000 50 000
3 26 500 30 000 60 000
4 36 000 40 000 70 000
A
The maximum use voltage is based on the following equations:
Maximum Maximum ac use voltage = 0.95 ac maximum retest voltage − 2 000
v
Classes 1, 2, 3, and 4.
Maximum Maximum ac use voltage = 0.95 dc maximum retest voltage − 30
v
Classes 1, 2, 3, and 4.
Maximum Maximum ac use voltage = 0.95 dc maximum retest voltage − 18
v
Class 0.
F479 − 06 (2017)
8.2 The test apparatus shall be designed to afford the operator full protection in the performance of his duties. Reliable means
of de-energizing and grounding the high voltage circuit shall be provided. It is particularly important to incorporate positive means
of grounding the high voltage section of dc test apparatus due to the likely presence of high-voltage capacitance charges at the
conclusion of the test. See ANSI C39.5.
8.2.1 To eliminate damaging ozone and possible flashover along the blanket, there should be a sufficient flow of air into and
around the blanket and an exhaust system to adequately remove ozone from the test machine. Consistent ozone cutting and
checking during the test procedure should be cause to ascertain the adequacy of the exhaust system.
8.2.2 The equipment shall be inspected at least annually to ensure that the general condition of the equipment is acceptable and
to verify the characteristics and accuracy of the test voltages. To ensure the continued accuracy of the test voltage, as indicated
by the test equipment voltmeter, the test equipment shall be calibrated at least annually, in accordance with the latest revision of
Practice D2865.
8.3 Both ac and dc voltage retest methods are included and either method may be selected for electrical testing.
8.4 All electrical tests shall be performed on clean blankets at normal room temperatures.
NOTE 1—All blankets should be in an unstressed physical condition prior to testing. Failure to achieve this may result in excessive breakdown or
damage.
8.5 AC Test:
8.5.1 Voltage Supply and Regulation—The voltage supply and its control equipment shall be of such size and design that, with
the test specimens in the circuit, the crest factor (ratio of peak to mean effective) of the test voltage shall differ by not more than
5 % from that of a sinusoidal wave over the upper half of the range of the test voltage. The accuracy of the voltage measuring
circuit shall be within 62 % of full scale. The correct rms value of the sinusoidal voltage wave form applied to the blanket may
be measured by one of the following methods:
8.5.1.1 A voltmeter used in conjunction with a calibrated instrument transformer connected directly across the high voltage
circuit,
8.5.1.2 A calibrated electrostatic voltmeter connected directly across the high voltage circuit, or
8.5.1.3 An ac meter connected in series with appropriate high-voltage type resistors directly across the high voltage circuit.
8.5.1.4 The crest factor may be checked by the use of a peak reading voltmeter connected directly across the high-voltage
circuit.
8.5.2 AC Retest:
8.5.2.1 Each blanket shall be given an electrical retest in accordance with 8.1. The test period shall start at the instant that the
prescribed testing voltage is reached.
NOTE 2—It is recommended that the retest voltage be applied initially at a low value and increased at a constant rate-of-rise of approximately 1000
V/s until the prescribed test voltage level is reached. Unless an electrical puncture has already occurred, the applied voltage should be reduced to at least
half v
...
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