1、Designation: F 479 06Standard Specification forIn-Service Care of Insulating Blankets1This standard is issued under the fixed designation F 479; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in
2、 parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 ofworkers from acciden
3、tal contact with live electrical conduc-tors, apparatus, or circuits. The product requirements andacceptance testing are as shown in Specification D 1048.1.2 This standard does not purport to address all of thesafety problems, if any, associated with its use. It is theresponsibility of the user of t
4、his standard to establish appro-priate safety and health practices and 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:2D 1048 Specification for Rubber Insulating BlanketsD 2865
5、Practice for Calibration of Standards and Equip-ment for Electrical Insulating Materials TestingF 819 Terminology Relating to Electrical Protective Equip-ment for Workers2.2 ANSI Standard:3C 39.5 Safety Requirements for Electrical and ElectronicMeasuring and Controlling InstrumentationC 84.1 Voltage
6、 Ratings for Electric Power Systems andEquipment (60 Hz)3. Terminology3.1 Definitions: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 bl
7、ankets or affecting theirapplication, use, or acceptability.3.1.3 designated personan 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 electric
8、al testing of electrical insulating protective equip-ment.3.1.5 electrodethe energized 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
9、and over or around, but not through, theequipment being tested.3.1.7 insulatedseparated 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
10、 insulated in a suitable manner forthe conditions to which it is subjected. Otherwise, it is, withinthe purposes of this definitions, unisulated. Insulating coveringof conductors is one means of making the conductor insulated.3.1.8 ozonea very active form of oxygen that may beproduced by corona, arc
11、ing, or ultra-violet rays.3.1.9 ozone cutting and checkingthe cracks produced 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 bla
12、nketsblankets that are in storageprior to being issued for use.3.1.12 voltage, maximum usethe ac voltage (rms), classi-fication of the protective equipment that designates the maxi-mum nominal design voltage of the energized system that maybe safely worked. The nominal design voltage is equal to the
13、phase-to-phase voltage on multiphase circuits.3.1.12.1 If there is no multiphase exposure in a system area,and the voltage exposure is limited to the phase (polarity on dcsystems) to ground potential, the phase (polarity on dc sys-tems) to ground potential shall be considered to be the nominaldesign
14、 voltage.1This specification is under the jurisdiction of ASTM Committee F18 onElectrical Protective Equipment for Workers and is the direct responsibility ofSubcommittee F18.25 on Insulating Cover-up Equipment.Current edition approved September 1, 2006. Published September 2006.Originally approved
15、in 1976. Last previous edition approved in 2001 asF 479 95(2001).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM webs
16、ite.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.12.2 If electrical equipment and devices are insul
17、ated orisolated, or both, such that the multiphase exposure on agrounded wye circuit is removed, then the nominal designvoltage may be considered as the phase-to-ground voltage onthat circuit.3.1.12.3 DiscussionThe work practices and methods as-sociated with removing mulitphase exposures at any give
18、nwork site are not addressed in the ASTM standards. The usersof ASTM standards should reference appropriate industryconsensus standards for proper work practices.3.1.13 voltage, maximum retestthe voltage, either ac rmsor dc avg, that is equal to the proof test voltage for newprotective equipment.3.1
19、.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.3.1.15 voltage, nominal designa nominal value consistentwith ANSI C 84.1-2001, assigned to the circuit or system forthe purpose of con
20、veniently designating its voltage class.3.2 For definitions of other terms, refer to TerminologyF 819.4. Significance and Use4.1 Compliance with this specification should continue toprovide personnel with insulating blankets of known andacceptable quality after initial acceptance in accordance withS
21、pecification D 1048. The standards herein are to be consid-ered as 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
22、 from a high-gradecis-1,4-polyisoprene rubber compound 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 D 1048.5
23、.5 Style A, constructed of the elastomers indicated underType 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
24、of the blankets.6. Safety Precautions6.1 A margin of 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
25、.6.2 The user of this type of protective equipment shall 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 th
26、e electrical testing facility is asfollows: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, and7.1.5 Packing for storage and shipping.7.2 Dirty blankets should be cleaned. They may be washedwith a mild soap or mild dete
27、rgent and water. Mild household-type chlorine bleach 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 grim
28、e may be wiped off using acompatible solvent.7.2.1 The 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
29、If washed, blankets should be air-dried. The air tempera-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 thes
30、e conditions are found, blanketsshall be rejected or 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 shallwithst
31、and the 60-Hz ac test voltage (rms value) or the dcvoltage (average value) specified in Table 1. The re-test shallbe performed in accordance with Section 8 and shall beconducted continuously for not less than 1 min, and not morethan 3 min.8.1.1 The interval between date of issue and retests shall be
32、based on work practices and test experience, but shall notexceed 1 year. Blankets that have been tested electrically, butTABLE 1 Voltage Requirements for BlanketsClassDesignation ofBlanketsAC UseVoltage,rms, maxAAC RetestVoltage,maxDC RetestVoltage,max0 1 000 5 000 20 0001 7 500 10 000 40 0002 17 00
33、0 20 000 50 0003 26 500 30 000 60 0004 36 000 40 000 70 000AThe 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 a
34、c use voltage = 0.95 dc maximum retest voltage 18 000vClass 0.F479062not 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
35、 a blanket, anelectrical test shall be performed 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 part
36、icularly important toincorporate positive means 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 C 39.5.8.2.1 To eliminate damaging ozone and possible flashoveralong the blanket, there shoul
37、d be a sufficient flow of air intoand around the 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 leas
38、t annually toensure that the general condition of 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,
39、 in accordance with thelatest revision of Practice D 2865.8.3 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 unstres
40、sed physical conditionprior to testing. Failure to 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
41、ofpeak to mean effective) of the test voltage shall 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
42、 appliedto the blanket may be measured by one of the 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, or
43、8.5.1.3 An ac meter connected in series with appropriatehigh-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 gi
44、ven an electrical retest inaccordance with 8.1. The 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 pres
45、cribed test voltage level is reached. Unless anelectrical 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 o
46、ver the test area to minimize coronaand mechanical 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
47、havingedges and corners rounded smoothly and wet pads 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 m
48、ask method may be used.A0.12 to 0.18 in.(3 to 5 mm) thick sheet of insulating material which is a minimum of 50in.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 fille
49、d 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 electrode, isplaced on top of the blanket. The wet pad is energized with the testvoltage. This method will test a 30 by 30 in. (762 by 762 mm) area of a36 by 36 in. (914 by 914 mm) blanket at 40 kV ac as the mask preventsflashover.Other electrode designs may be
