1、Designation: F2676 09F2676 16Standard Test Method forDetermining the Protective Performance of an ArcProtective Blanket for Electric Arc Hazards1This standard is issued under the fixed designation F2676; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is used to evaluate the ability of the arc protective blankets to wi
3、thstand the effects of arc flash and arcblast in a configuration in which the blanket is hung or anchored near energized equipment. Specifically, this test method is usedto determine the arc protective blankets (1) resistance to breakopen, (2) mechanical strength, and (3) ability to self-extinguishf
4、lames following a controlled arc exposure.1.2 This method is used to determine the performance of arc protective blankets in terms of: maximum arc current levelexpressed in kA and BTP (BTP) expressed as the product of arc current in kA and arc duration in number of cycles to causebreakopen (kA*cycle
5、s). Cycles are on the basis of 60 Hz.1.3 Blanket test specimens used in this test method are test size blankets of 152 6 5 cm (60 6 2 in.) by 122 6 5 cm (48 62 in.). The test specimen size is for testing purposes only. Commercially available arc protective blankets either larger or smallerthan the t
6、est specimen size are covered by this standard.1.4 The arc protective blankets described in this test method are made of flame-resistant materials and are available in varyingsizes and configurations based on the application.1.5 This test method shall be used to measure and describe the properties o
7、f materials, products, or assemblies in response toincident thermal (convective and radiant) and pressure energies generated by an electric arc under controlled laboratory conditions.1.6 The values stated in SI units shall be regarded as standard. The values given in parentheses are mathematical con
8、versionto inch-pound or other units commonly used for arc testing.1.7 This standard shall not be used to describe or appraise the fire hazard or fire risk of materials, products, or assemblies underactual fire conditions. However, results of this test may be used as elements of a fire assessment, wh
9、ich takes into account all ofthe factors, which are pertinent to an assessment of the fire hazard of a particular end use.1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appro
10、priate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific precautions, see Section 7.2. Referenced Documents2.1 ASTM Standards:2D4391 Terminology Relating to The Burning Behavior of TextilesF819 Terminology Relating to Electrical Protectiv
11、e Equipment for Workers3. Terminology3.1 Definitions:3.1.1 arc, nconductive path in air for the electric current caused by ionization of air between two electrodes.3.1.2 arc induced fragmentation, nmolten metal fragments or other fragments emitted from an electric arc.1 This test method is under the
12、 jurisdiction of ASTM Committee F18 on Electrical Protective Equipment for Workers and is the direct responsibility of SubcommitteeF18.65 on Wearing Apparel.Current edition approved May 1, 2009April 1, 2016. Published June 2009April 2016. Originally approved in 2009. Last previous edition approved i
13、n 2009 as F2676-09.DOI: 10.1520/F2676-09.10.1520/F2676-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.Thi
14、s 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. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editio
15、ns as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.3 arc protective blanket, na flat assembly of f
16、abric(s) with locations for attachment used to protect workers from theeffects of arc flash and arc blast.3.1.4 arc protective blanket maximum arc current Imax,nmaximum value of RMS arc current that blanket can withstandwithout breakopen for no less than ten cycles of 60 Hz.3.1.4.1 DiscussionStandar
17、d values of the maximum arc current for this test method are 15 kA, 25 kA, or 40 kA.3.1.5 arc protective blanket breakopen threshold performance (BTP) , nthe product of the arc current I, kA and arc durationin cycles required for breakopen to occur at this same arc current level.3.1.6 breakopen, nin
18、 electrical arc testing, a material response evidenced by the formation of one or more holes in thematerial which may allow thermal energy to pass through the material.3.1.6.1 DiscussionThe instant of breakopen will only be visible with a high-speed (HS) camera. The size of the breakopen will quickl
19、y expand asthe arc blows through the blanket and burns back the edges of the materials. The final size of the breakopen hole is not significant,as it will depend to a great extent on the duration of the arc once the breakopen point is reached. The important measure usingthe HS camera is the time fro
20、m arc initiation to the first evidence of arc plasma through the blanket.3.1.7 charring, nthe formation of carbonaceous residue as the result of pyrolysis or incomplete combustion.3.1.8 directional arc, nin arc protective blanket testing, an arc expanding in direction of the blanket perpendicular to
21、 andcentered to the blanket plane.3.1.9 dripping, nin arc testing, a material response evidenced by flowing of a specimens material of composition and dropletsseparation from the material.3.1.10 embrittlement, nthe formation of a brittle residue as the result of pyrolysis or incomplete combustion.3.
22、1.11 ignition, nthe initiation of combustion.3.1.12 ignitability, n (ignitable, adj)in electric arc exposure, the property of a material involving ignition accompanied by heatand light, and continued burning resulting in consumption of at least 25 % of the exposed area of the test specimen.3.1.13 me
23、chanical strength, nfor an arc protective blanket, the ability to remain attached to its support(s) in essentially itsoriginal configuration.3.1.14 peak arc current, nmaximum value of the AC arc current, A.3.1.15 pressure wave, na certain force over an area created by air movement caused by an elect
24、ric arc.3.1.16 RMS arc current, nroot mean square of the AC arc current, A.3.1.17 shrinkage, na decrease in one or more dimensions of an object or material.3.2 For definitions of other terms see Terminologies D4391 or F819.4. Summary of Test Method4.1 This test method determines resistance to breako
25、pen and mechanical strength under directional arc exposure, ability toself-extinguish flames and the afterflame time of the exposed arc protective blankets. This test method simulates a condition in avault or substation or energy center where arc protective blanket may be attached to provide protect
26、ion from the thermal effectsand the pressure wave experienced during an electrical arc fault. This test method replicates most severe conditions when the arcis directed and focused on the blanket.4.2 This test method determines two ratings for arc protective blanket: Maximum Arc Current, Imax, and B
27、TP.4.3 Three nominal values of Imax are established in this test method: 15 kA, 25 kA and 40 kA. In this test method each arcprotective blanket test specimen is intentionally forced to break open. To be considered arc rated, blanket shall withstand threetimes at least one of the nominal values of Im
28、ax without breakopen during at least 10 cycles.NOTE 1Additional testing at a higher Imax than 40 kA is permitted but the arc protective blanket shall be rated at one of the three nominal valuesof Imax which shall be the official rating.4.4 BTP is determined as the product of arc current and arc dura
29、tion causing breakopen. Arc duration is the number of 60 Hzcycles between arc initiation and breakopen of the blanket.4.5 BTP is determined for at least three different arc current levels. A minimum value of BTP is assigned as arc rating to anarc protective blanket.F2676 1624.6 In this test method t
30、he arc electrodes configuration is designed so that the arc blast projects directionally towards the testspecimen.4.7 This test method involves observing HS video recordings to determine test specimen breakopen and afterflame time. Eachtrial is recorded with a HS video camera.5. Significance and Use
31、5.1 This test method determines the effectiveness of arc protective blankets in suprressing the combined effects of an arc flashand arc blast.5.2 The arc exposure energy is produced from controlled phase-to-ground arc fault. The resulting arc flash and blast energy areintentionally directed onto the
32、 test specimen to simulate worst case conditions.5.3 Test results will describe the maximum arc current and product of arc current and cycles at which test specimens block theenergy without breakopen, ability to self-extinguish afterflaming, afterflame time and the detection of mechanical attachment
33、failures during testing. Mechanical attachment failure and afterflame time are obtained from visual observations and videorecording after each arc exposure.5.4 This test method maintains the arc protective blanket in a vertical position and does not involve movement except thatresulting from the arc
34、 exposure.5.5 In this test method, test specimens are exposed at three arc current levels to determine the test specimens performance.NOTE 2In experimental testing, some blankets increase in protection (in value of kA*cycles to cause breakopen) as the arc current increases and somedecrease as shown
35、in Fig. 1. This test method is designed to recognize this behavior and to specify testing over the range of arc current levels includinglower levels of 5 kA or 10 kA, or both.5.6 This test method specifies a standard set of exposure conditions. Different exposure conditions may produce different res
36、ults.NOTE 3In addition to the standard set of exposure conditions, it is permitted to test using other conditions representative of the expected hazard,reported all non-standard test conditions that are used.6. Apparatus6.1 General Arrangement for Testing of Arc Protective BlanketsThe test apparatus
37、 shall consist of a vault containing anelectrode system and a blanket test specimen holding structure and a HS camera positioned outside the vault. A top view of thetest apparatus in Fig. 2 shows the suggested electrode mounting supports.6.2 Arrangement of the Vault:6.2.1 Internal dimensions of the
38、vault shall be 2.2 6 0.3 m (7 6 1 ft) wide, 2.2 6 0.3 m (7 6 1 ft) high and 2.2 6 0.3 m (76 1 ft) deep.FIG. 1 Example of Performance Trend for Different BlanketsF2676 1636.2.2 The vault shall have three solid walls (back and two sides), floor and roof and be capable of withstanding the entire rangeo
39、f test conditions.6.2.3 The front is open for access to electrode system and blanket-holding structure and for providing a view for the HS camera.6.2.4 The roof, floor and walls of the vault shall have no opening.6.2.5 The vault may be constructed of concrete or framed plywood finished with non-cond
40、uctive heat-resistant material.6.3 Arrangement of Arc Electrodes and Supply Bus Arc electrodes shall be arranged pointing at the center of the testspecimen.6.3.1 Two arc electrodes shall penetrate into the vault through a side wall.6.3.2 Material and diameter of the arc electrodes shall be stainless
41、 steel copper rod with 18-mm (0.75-in.) diameter.6.3.3 The arc electrodes shall be positioned horizontally, parallel to each other, equidistant from the floor and the roof in verticalplane and equidistant from back wall and front opening in horizontal plane.NOTE 4Electromagnetic forces generated by
42、arc current can bend or move parallel electrodes. In order to keep electrodes parallel, it is recommendedto use spacers made of insulating materials.6.3.4 The spacing between parallel arc electrodes shall be 10 6 0.6 cm (4 6 0.25 in.). This spacing is equal to arc gap in thistest method.FIG. 2 Test
43、Cubicle Set UpF2676 1646.3.5 The arc electrodes shall protrude into the vault for the distance of approximately 30 cm (12 in.) and be terminated to asupply bus outside the vault. The electrode distance to the blanket is 6 in.; this requires to be adjusted before every test.6.3.6 Care must be taken i
44、n the position and configuration of the supply bus or feeding cables to the arc electrodes as not toadversely affect the direction or motion of the arc. For testing purposes, the arc is directed towards the blanket test specimenproviding a controlled test exposure. The general arrangement of supply
45、buses and arc electrodes is shown in Fig. 2.6.4 Arrangement of Blanket Test SpecimenThe test specimen of the arc protective blanket shall be arranged perpendicular toarc electrodes and at the distance of 15 6 1 cm (6 6 0.5 in.), from the tips of the arc electrodes.6.4.1 The test specimen shall be at
46、tached to the blanket holding structure.6.4.2 The blanket holding structure shall have the dimensions of 183 6 2.5 cm (72 6 1 in.) by 152 6 2.5 cm (6061 in.).6.4.3 The blanket holding structure shall be mounded vertically and parallel to the side wall of the vault and at the distance of46 cm (18 in.
47、) from the side wall.6.4.4 The blanket holding structure shall be equidistant from the floor and the roof in a vertical plane and equidistant from backwall and front opening in a horizontal plane.6.4.5 The center of the test specimen shall be aligned with the midpoint of the arc gap.6.5 Fuse WireAfu
48、se wire, connecting the ends of electrodes tips, is used to initiate the arc. This wire is consumed during thetest. The fuse wire shall be a copper 16 gauge wire.6.6 Electric SupplyThe electric supply shall be sufficient to allow for the discharge of an electric arc with a gap of up to 10cm (4 in.),
49、 with alternating arc current from 5 kA up to 50 kA and with arc duration from 0.05 s (3 cycles at 60 Hz) up to 2.5 s(150 cycles at 60 Hz). The arc shall not self extinguish during the test. The X/R ratio fo the test circuit shall be such that the testcurrent contains a DC component resulting in the first peak of the test current having a magnitude of 2.3 times the symmetricalRMS value.6.7 Test Circuit ControlRepeat exposures of the arc currents shall be within the tolerance of the selected test level. The makeswitch shall be capable of point on w
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