1、Designation: F479 06 (Reapproved 2011)Standard Specification forIn-Service Care of Insulating Blankets1This standard is issued under the fixed designation F479; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers the in-service care, inspection,testing, and use voltage of insulating blankets for protection ofworke
3、rs from accidental contact with live electrical conduc-tors, apparatus, or circuits. The product requirements andacceptance testing are as shown in Specification D1048.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions
4、 to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety problems, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and
5、determine the applica-bility of regulatory limitations prior to use. See Section 6 and8.2 for specific precautionary statements.2. Referenced Documents2.1 ASTM Standards:2D1048 Specification for Rubber Insulating BlanketsD2865 Practice for Calibration of Standards and Equipmentfor Electrical Insulat
6、ing Materials TestingF819 Terminology Relating to Electrical Protective Equip-ment for Workers2.2 ANSI Standard:3C39.5 Safety Requirements for Electrical and ElectronicMeasuring and Controlling InstrumentationC84.1 Voltage Ratings for Electric Power Systems andEquipment (60 Hz)3. Terminology3.1 Defi
7、nitions:3.1.1 breakdownthe electrical discharge or arc occurringbetween the electrodes and through the equipment being tested.3.1.2 compatiblenot injurious to or changing the physicalor electrical characteristics of the blankets or affecting theirapplication, use, or acceptability.3.1.3 designated p
8、ersonan individual who is qualified byexperience or training to perform an assigned task.3.1.4 electrical testing facilitya location with qualifiedpersonnel, testing equipment, and procedures for the inspectionand electrical testing of electrical insulating protective equip-ment.3.1.5 electrodethe e
9、nergized or grounded conductor por-tion of electrical test equipment which is placed near or incontact with the material or equipment being tested.3.1.6 flashoverthe electrical discharge or arc occurringbetween electrodes and over or around, but not through, theequipment being tested.3.1.7 insulated
10、separated from other conducting surfacesby a dielectric substance (including air space) offering a highresistance to the passage of current.3.1.7.1 DiscussionWhen any object is said to be insu-lated, it is understood to be insulated in a suitable manner forthe conditions to which it is subjected. Ot
11、herwise, it is, withinthe purposes of this definitions, uninsulated. Insulating cover-ing of conductors is one means of making the conductorinsulated.3.1.8 ozonea very active form of oxygen that may beproduced by corona, arcing, or ultraviolet rays.3.1.9 ozone cutting and checkingthe cracks produced
12、 byozone in a material under mechanical stress.3.1.10 retestthe tests given after the initial acceptance testusually performed at regular periodic intervals or as requiredbecause of physical inspection.3.1.11 unassigned blanketsblankets that are in storageprior to being issued for use.3.1.11.1 volta
13、ge, maximum usethe ac voltage (rms), clas-sification of the protective equipment that designates themaximum nominal design voltage of the energized system that1This specification is under the jurisdiction of ASTM Committee F18 onElectrical Protective Equipment for Workers and is the direct responsib
14、ility ofSubcommittee F18.25 on Insulating Cover-Up Equipment.Current edition approved Dec. 1, 2011. Published January 2012. Originallyapproved in 1976. Last previous edition approved in 2006 as F47906. DOI:10.1520/F0479-06R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orco
15、ntact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyrig
16、ht ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.may be safely worked. The nominal design voltage is equal tothe phase-to-phase voltage on multiphase circuits.3.1.11.2 DiscussionIf there is no multiphase exposure in asystem area, and the volt
17、age exposure is limited to the phase(polarity on dc systems) to ground potential, the phase (polarityon dc systems) to ground potential shall be considered to be thenominal design voltage.3.1.11.3 DiscussionIf electrical equipment and devicesare insulated or isolated, or both, such that the multipha
18、seexposure on a grounded wye circuit is removed, then thenominal design voltage may be considered as the phase-to-ground voltage on that circuit.3.1.11.4 DiscussionThe work practices and methods as-sociated with removing multiphase exposures at any givenwork site are not addressed in the ASTM standa
19、rds. The usersof ASTM standards should reference appropriate industryconsensus standards for proper work practices.3.1.12 voltage, maximum retestthe voltage, either ac rmsor dc avg, that is equal to the proof test voltage for newprotective equipment.3.1.13 voltage, nominal designa nominal value cons
20、istentwith ANSI C84.1-2001, assigned to the circuit or system forthe purpose of conveniently designating its voltage class.3.1.14 voltage, retestthe voltage, either ac rms or dc avg,that used protective equipment must be capable of withstand-ing for a specified test period without breakdown.3.2 For
21、definitions of other terms, refer to TerminologyF819.4. Significance and Use4.1 Compliance with this specification should continue toprovide personnel with insulating blankets of known andacceptable quality after initial acceptance in accordance withSpecification D1048. The standards herein are to b
22、e consideredas minimum requirements.5. Classification5.1 Blankets covered under this specification shall be des-ignated 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-gradecis-1,4-polyisoprene rubber compou
23、nd of natural or syntheticorigin, properly vulcanized.5.3 Type II, ozone-resistant, made of any elastomer orcombination of elastomeric compounds.5.4 The class designation shall be based on the electricalproperties as shown in Specification D1048.5.5 Style A, constructed of the elastomers indicated u
24、nderType I or Type II, shall be free of any reinforcement.5.6 Style B, constructed of the elastomers indicated underType I or Type II, shall incorporate a reinforcement. Thisreinforcement shall not affect adversely the dielectric charac-teristics of the blankets.6. Safety Precautions6.1 A margin of
25、safety shall be provided between themaximum use voltage on which the blankets are used and thevoltage at which they are retested. The relationship betweenretest voltage and maximum use voltage at which the blanketsshall be used is shown in Table 1.6.2 The user of this type of protective equipment sh
26、all beknowledgeable of and instructed in the correct and safe visualinspection and use of this equipment.7. Inspection and Testing at an Electrical Testing Facility7.1 The recommended sequence for inspection and testingof insulating blankets at the electrical testing facility is asfollows:7.1.1 Chec
27、k in, washing, and preliminary inspection,7.1.2 Electrical test,7.1.3 Final inspection,7.1.4 Recordkeeping and marking, and7.1.5 Packing for storage and shipping.7.2 Dirty blankets should be cleaned. They may be washedwith a mild soap or mild detergent and water. Mild household-type chlorine bleach
28、may be used for disinfectant purposes.Soaps, detergents, and bleaches shall not be used at strengthsthat would attack or harm the rubber surface. They shall berinsed thoroughly with water to remove all of the soap ordetergent. Severe dirt and grime may be wiped off using acompatible solvent.7.2.1 Th
29、e cleaning agent shall not degrade the insulating orphysical qualities of the blankets.7.2.2 A commercial tumble type washing machine may beused. Caution must be observed to eliminate any interiorsurfaces or edges that may damage the blankets.7.3 If washed, blankets should be air-dried. The air temp
30、era-ture should not be over 150F (65.5C).7.4 Prior to the electrical test, the blankets shall be given apreliminary inspection for punctures, cuts, corona cutting, orany obvious condition which would adversely affect theperformance. If any of these conditions are found, blanketsshall be rejected or
31、repaired.7.5 The blankets shall be tested in accordance with Section8.7.6 After the test, the blankets shall be given an inspectionfor corona and ozone damage.8. Electrical Tests8.1 All blankets issued for service shall be retested and shallwithstand the 60-Hz ac test voltage (rms value) or the dcvo
32、ltage (average value) specified in Table 1. The retest shall beTABLE 1 Voltage Requirements for BlanketsClassDesignation ofBlanketsAC UseVoltage,rms, maxAAC RetestVoltage,maxDC RetestVoltage,max0 1000 5000 20 0001 7500 10 000 40 0002 17 000 20 000 50 0003 26 500 30 000 60 0004 36 000 40 000 70 000AT
33、he maximum use voltage is based on the following equations:Maximum ac use voltage = 0.95 ac maximum retest voltage 2 000vClasses 1, 2, 3, and 4.Maximum ac use voltage = 0.95 dc maximum retest voltage 30 500vClasses 1, 2, 3, and 4.Maximum ac use voltage = 0.95 dc maximum retest voltage 18 000vClass 0
34、.F479 06 (2011)2performed in accordance with Section 8 and shall be conductedcontinuously for not less than 1 min, and not more than 3 min.8.1.1 The interval between date of issue and retests shall bebased on work practices and test experience, but shall notexceed 1 year. Blankets that have been tes
35、ted electrically, butnot issued for service, shall not be placed into service unlessthey have been tested electrically within the previous 12months.8.1.2 Where a visual inspection indicates that there may bereason to suspect the electrical integrity of a blanket, anelectrical test shall be performed
36、 before reissuing the blanketfor service.8.2 The test apparatus shall be designed to afford theoperator full protection in the performance of his duties.Reliable means of de-energizing and grounding the highvoltage circuit shall be provided. It is particularly important toincorporate positive means
37、of grounding the high voltagesection of dc test apparatus due to the likely presence ofhigh-voltage capacitance charges at the conclusion of the test.See ANSI C39.5.8.2.1 To eliminate damaging ozone and possible flashoveralong the blanket, there should be a sufficient flow of air intoand around the
38、blanket and an exhaust system to adequatelyremove ozone from the test machine. Consistent ozone cuttingand checking during the test procedure should be cause toascertain the adequacy of the exhaust system.8.2.2 The equipment shall be inspected at least annually toensure that the general condition of
39、 the equipment is acceptableand to verify the characteristics and accuracy of the testvoltages. To ensure the continued accuracy of the test voltage,as indicated by the test equipment voltmeter, the test equipmentshall be calibrated at least annually, in accordance with thelatest revision of Practic
40、e D2865.8.3 Both ac and dc voltage retest methods are included andeither method may be selected for electrical testing.8.4 All electrical tests shall be performed on clean blanketsat normal room temperatures.NOTE 1All blankets should be in an unstressed physical conditionprior to testing. Failure to
41、 achieve this may result in excessive breakdownor damage.8.5 AC Test:8.5.1 Voltage Supply and RegulationThe voltage supplyand its control equipment shall be of such size and design that,with the test specimens in the circuit, the crest factor (ratio ofpeak to mean effective) of the test voltage shal
42、l differ by notmore than 5 % from that of a sinusoidal wave over the upperhalf of the range of the test voltage. The accuracy of the voltagemeasuring circuit shall be within 62 % of full scale. Thecorrect rms value of the sinusoidal voltage wave form appliedto the blanket may be measured by one of t
43、he followingmethods:8.5.1.1 A voltmeter used in conjunction with a calibratedinstrument transformer connected directly across the highvoltage circuit,8.5.1.2 A calibrated electrostatic voltmeter connected di-rectly across the high voltage circuit, or8.5.1.3 An ac meter connected in series with appro
44、priatehigh-voltage type resistors directly across the high voltagecircuit.8.5.1.4 The crest factor may be checked by the use of a peakreading voltmeter connected directly across the high-voltagecircuit.8.5.2 AC Retest:8.5.2.1 Each blanket shall be given an electrical retest inaccordance with 8.1. Th
45、e test period shall start at the instantthat the prescribed testing voltage is reached.NOTE 2It is recommended that the retest voltage be applied initiallyat a low value and increased at a constant rate-of-rise of approximately1000 V/s until the prescribed test voltage level is reached. Unless anele
46、ctrical puncture has already occurred, the applied voltage should bereduced to at least half value at the end of the test period before openingthe test circuit.8.5.2.2 Electrodes shall be of such design so as to apply theelectrical stress uniformly over the test area to minimize coronaand mechanical
47、 strain in the material. The electrodes used inthe proof test shall be designed to comply with the flashoverclearances specified in Table 2.NOTE 3Recommended Electrodes for Classes 0, 1, and2Rectangular metal sheets approximately116 in. (2 mm) thick havingedges and corners rounded smoothly and wet p
48、ads approximately14 in. (6mm) thick, placed between the metal sheets and the blanket.Recommended Electrodes for Classes 3 and 4Maximum area can betested when both electrodes are the same size. When an insulated table isnot convenient, the following mask method may be used. A 0.12 to 0.18in. (3 to 5
49、mm) thick sheet of insulating material which is a minimum of50 in.2(1270 mm2) and has a 30 by 30 in. (762 by 762 mm) opening in thecenter, is placed on a grounded metal plate. This mask which has a“picture frame” appearance shall have the opening filled with a conductivematerial of such thickness as to bring the ground electrode to approxi-mately the same level as the mask in order to maintain direct contact withthe blanket to be tested. The blanket is placed over the ground electrode,and a wet pad approximately the same size as the ground electrod
