1、Designation: F 2522 05Standard Test Method forDetermining the Protective Performance of a ShieldAttached on Live Line Tools or on Racking Rods for ElectricArc Hazards1This standard is issued under the fixed designation F 2522; the number immediately following the designation indicates the year ofori
2、ginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is used to determine the heat attenua-tion f
3、actor (HAF), the effective heat attenuation factor (EHAF),and the shields mechanical strength (SMS) of a shield attachedon live line tools or racking rods intended for protection ofworkers exposed to electric arcs.1.2 The materials used in this test method of workerprotection are in the form of a sh
4、ield attached on live line toolsor on the racking rods.1.3 The protective shield described in this test method shallbe transparent and shall be easily attached and removed fromlive line tools or from racking rods.1.4 The protective shield described in this test method has24-in. (0.61-m) diameter and
5、 can be used for most applications,however for special cases, the shield can have different sizes tosuit the protective requirements of the application.1.5 This standard shall be used to measure and describe theproperties of materials, products, or assemblies in response toincident energies (thermal
6、-convective, and radiant and pressurewave) generated by an electric arc under controlled laboratoryconditions and does not purport to predict damage from light,resultant pressure impact other than the pressure and thermalaspects measured.1.6 UnitsThe values stated in inch-pound units are to beregard
7、ed as standard. The values given in parentheses aremathematical conversions to SI units that are provided forinformation only and are not considered standard.1.7 This standard shall not be used to describe or appraisethe fire hazard or fire risk of materials, products, or assembliesunder actual fire
8、 conditions. However, results of this test maybe used as elements of a fire assessment, which takes intoaccount all of the factors, which are pertinent to an assessmentof the fire hazard of a particular end use.1.8 This standard does not purport to address all of thesafety concerns, if any, associat
9、ed with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificprecautions, see Section 7.2. Referenced Documents2.1 ASTM Standards:2D 4391 Terminology Re
10、lating to Burning Behavior of Tex-tilesF 1959/F 1959M Test Method for Determining the ArcRating of Materials for Clothing3. Terminology3.1 Definitions:3.1.1 arc, nconductive path in air for the electric currentcaused by ionization of air between two electrodes.3.1.2 arc duration, ntime duration of t
11、he arc, s.3.1.3 arc energy, vi dt, nsum of the instantaneous arcvoltage values multiplied by the instantaneous arc currentvalues multiplied by the incremental time values during thearc, J.3.1.4 arc gap, ndistance between the arc electrodes.3.1.5 arc voltage, nvoltage across the gap caused by thecurr
12、ent flowing through the resistance created by the arc gap,V. See also Terminology D 4391.3.1.6 asymmetrical arc current, nthe total arc currentproduced during closure; it includes a direct component and asymmetrical component, A.3.1.7 blowout, nthe extinguishing of the arc caused by amagnetic field.
13、3.1.8 closure, npoint on supply current wave form wherearc is initiated.3.1.9 delta peak temperature, ndifference between themaximum temperature and the initial temperature of the sensorduring the test, C.3.1.10 effective heat attenuation (EHAF)/cone of protection(COP) factor, nthe percentage of the
14、 incident heat energythat is attenuated by the shield at the location of the worker.1This test method is under the jurisdiction of ASTM Committee F18 onElectrical Protective Equipment for Workers and is the direct responsibility ofSubcommittee F18.35 on Tools and Equipment.Current edition approved O
15、ct. 1, 2005. Published November 2005.2For 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 website.1Copyright ASTM Internat
16、ional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.11 fragmentation, nmolten metal fragments or otherfragments emitted from an electric arc.3.1.12 heat attenuation factor (HAF), nthe percentage ofthe incident heat energy that is blocked by the safety shiel
17、dmaterial.3.1.13 heat flux, nthe thermal intensity indicated by theamount of energy transmitted divided by area and timeW/m2cal/cm2s.3.1.14 i2t, nsum of the instantaneous arc current valuessquared multiplied by the incremental time values during thearc, A2/s.3.1.15 ignitability, n (ignitable, adj)in
18、 electric arc expo-sure, the property of a material involving ignition accompaniedby heat and light, and continued burning resulting in consump-tion of at least 25 % of the exposed area of the test specimen.3.1.16 ignition, nthe initiation of combustion.3.1.17 incident energy (Ei), nthe amount of en
19、ergy (totalheat, cal/cm2) received at a surface as a direct result of anelectrical arc discharge as measured by temperature rise oncopper calorimeters.3.1.18 peak arc current, nmaximum value of the AC arccurrent, A.3.1.19 pressure wave, na certain force over an areacreated by air movement caused by
20、an electric arc.3.1.20 RMS arc current, nroot mean square of the AC arccurrent, A.3.1.21 sensors, ncopper calorimeter, instrumented with athermocouple contained in a dielectric, heat protective housingfor use in measuring energy.3.1.22 shield mechanical strength value (SMS) factor,nthe mechanical ab
21、ility of the shield to withstand the electricarc pressure wave and fragmentation.3.1.23 time to delta peak temperature, nthe time frombeginning of the initiation of the arc to the time the delta peaktemperature is reached, s.3.1.24 X/R ratio, nthe ratio of system inductive reactanceto resistance. It
22、 is proportional to the L/R ratio of time constant,and is, therefore, indicative of the rate of decay of any DCoffset. A large X/R ratio corresponds to a large time constantand a slow rate of decay.4. Summary of Test Method4.1 This test method determines the heat attenuation factor(HAF) of the shiel
23、d material, the effective heat attenuationfactor (EHAF) at the location where the worker may be whileholding the hot stick or racking rod to which the shield isattached, and the shield mechanical strength (SMS). Thecopper calorimeters (incident energy monitoring sensors) areplaced for the HAF at the
24、 shield (front and back), and for theEHAF test at the probable location of the workers hand, head,side of the face, chest, and legs when exposed to the heatenergy from a controlled electric arc. The SMS value of theshield is obtained from visual observations of the HAF test forthe ability of the shi
25、eld to absorb and deflect the fragmentationshrapnel, not break or ignite, not to move from its attachment,and not to bend more then 20 degrees.4.2 During HAF and EHAF tests, the center of the shield isaligned with the mid point of the arc gap. During thisprocedure, the amount of heat energy reduced
26、(blocked) by theshield is measured during exposure to an electric arc.4.3 The heat energy of the arc exposure is measured withcalorimeters. The rate at which the temperature of the calorim-eters increases is a direct measure of the heat energy received.4.4 The shield protective performance for this
27、test method isdetermined from the heat attenuation factor (in percent) at theshield location, and from the effective heat attenuation factor atthe worker location. The effective heat attenuation factor inpercent is the difference in the incident energy generated by thearc flash before and after the
28、shield was used.4.5 Heat transfer data can be used to predict the onset ofsecond degree burn using the Stoll curve.4.6 This procedure incorporates incident heat energy moni-toring sensors.4.7 Further description of the shield reduction of the electricarc exposure on the worker is presented in Sectio
29、ns 12 and 13.5. Significance and Use5.1 This test method is intended for determining the heatattenuation factor (HAF) of a shield material and the effectiveheat attenuation factor (EHAF) at the location of the worker.This can be obtained by measuring the reduction of the arcincident energy levels ca
30、used by a shield attached on a live linetool (hot stick) or on a racking rod and designed for protectionfor workers exposed to electric arcs. The shield mechanicalstrength (SMS) can be obtained from visual observations of thehigh speed video recordings of each shot during HAF tests.5.1.1 Because of
31、the variability of the arc exposure, differ-ent heat transmission values and pressure may result forindividual sensors. The results of each sensor are evaluated inaccordance with Section 12.5.2 This test method maintains the shield and the heatsensors in a static, vertical position and does not invo
32、lvemovement except that resulting from the exposure.5.3 This test method specifies a standard set of exposureconditions. Different exposure conditions may produce differ-ent results.NOTE 1In addition to the standard set of exposure conditions, otherconditions representative of the expected hazard ma
33、y be used and shall bereported should this data be cited.6. Apparatus6.1 General Arrangement for Determining Heat AttenuationFactor (HAF) of the ShieldThe test apparatus shall consist ofsupply bus, arc controller, recorder, arc electrodes, the shield,and incident energy monitoring sensors. The arc e
34、xposure inthe form of heat attenuation factor at the shield location shallbe monitored with two incident energy monitoring sensors.Figs. 1 and 2 show the test set-up and the location of the shieldon the hot stick and on the racking rod and the location ofsensors. Fig. 2 has the same test set-up as F
35、ig. 1, except theshield is attached on the racking rod.6.2 General Arrangement for Determining Effective HeatAttenuation Factor (EHAF) at the Location of the WorkerThe test apparatus shall consist of supply bus, arc controller,recorder, arc electrodes, a shield, and incident energy monitor-ing senso
36、rs. The arc exposure in the form of effective heatattenuation factor at the location of the worker shall beF2522052monitored with a minimum of six incident energy monitoringsensors. Figs. 3 and 4 show the test set-up and the location ofthe shield and the sensors. The shield for the EHAF test is atth
37、e same location as in the HAF tests (Figs. 1 and 2) and thesensors are located approximately 5 ft (1.52 m) from theelectric arc center. Fig. 4 has the same test set-up as Fig. 3,except the shield in Fig. 4 is attached on the racking rod, andin Fig. 3 the shield is attached on a hotstick.d1 = 24 in.
38、(0.61 m), distance from the wall (back plate) to the arc electrodesd2=6in.(0.15m)(gap) between electrodesd3 = 53 in. (1.35 m), parallel distance of the hot stick or the racking rod above the floord4 = 24 in. (0.61 m), distance of the shield from the electrodesd5=4in.(0.10m),vertical distance between
39、 centers of S1 and S2S1 and S2 = 24.5 in. (0.62 m), approximate horizontal distance of the sensors from the electrodesS1, S2, S3, S4, S5, and S6 are located vertically, and S1 is 5 ft (1.52 m) from the arc centerFIG. 1 Test Set-up for HAF Measurements with Shield on a Live Line Toold1 = 24 in. (0.61
40、 m), distance from the wall (back plate) to the arc electrodesd2=6in.(0.15m)(gap) between electrodesd3 = 53 in. (1.35 m), parallel distance of the hot stick or the racking rod above the floord4 = 24 in. (0.61 m), distance of the shield from the electrodesd5=4in.(0.10m),vertical distance between cent
41、ers of S1 and S2S1 and S2 = 24.5 in. (0.62 m), approximate horizontal distance of the sensors from the electrodesS1, S2, S3, S4, S5, and S6 are located vertically, and S1 is 5 ft (1.52 m) from the arc centerFIG. 2 Test Set-up for HAF Measurements with Shield on a Racking RodF25220536.3 General Arran
42、gement for Determining Shields Me-chanical Strength (SMS)The evaluation of shields mechani-cal strength value (SMS) is based on visual observations of thehigh speed video recordings of the arc tests made in 6.1 (HAFtests). The purpose of the SMS test is to determine themechanical ability of the shie
43、ld to withstand the electric arcpressure wave and fragmentation. The SMS value is deter-mined by observing the HAF tests for the ability of the shieldto absorb and deflect the fragmentation shrapnel, not break orignite, not to move from its attachment, and not to bend morethen 20 degrees.6.4 Electro
44、desA typical arrangement of the arc electrodesis shown in Fig. 1. The arc shall be in a vertical position asshown.d1 = 24 in. (0.61 m), distance from the wall (back plate) to the arc electrodesd2=6in.(0.15m)(gap) between electrodesd3 = 53 in. (1.35 m), parallel distance of the hot stick or the racki
45、ng rod above the floord4 = 24 in. (0.61 m), distance of the shield from the electrodesd5=4in.(0.10m),vertical distance between centers of S1 and S2S1 and S2 = 24.5 in. (0.62 m), approximate horizontal distance of the sensors from the electrodesS1, S2, S3, S4, S5, and S6 are located vertically, and S
46、1 is 5 ft (1.52 m) from the arc centerFIG. 3 Test Set-up for EHAF Measurement with Shield on a Live Line Toold1 = 24 in. (0.61 m), distance from the wall (back plate) to the arc electrodesd2=6in.(0.15m)(gap) between electrodesd3 = 53 in. (1.35 m), parallel distance of the hot stick or the racking ro
47、d above the floord4 = 24 in. (0.61 m), distance of the shield from the electrodesd5=4in.(0.10m),vertical distance between centers of S1 and S2S1 and S2 = 24.5 in. (0.62 m), approximate horizontal distance of the sensors from the electrodesS1, S2, S3, S4, S5, and S6 are located vertically, and S1 is
48、5 ft (1.52 m) from the arc centerFIG. 4 Test Set-up for EHAF Measurement with Shield on a Racking RodF25220546.5 ElectrodesMake the electrodes from electrical gradecopper (alloy type 110) rod of a nominal34-in. (0.019-m)diameter. Lengths of 18 in. (0.460 m) long have been found tobe adequate.6.6 Fus
49、e WireA fuse wire, connecting the ends of oppos-ing electrodes tips, is used to initiate the arc. This wire isconsumed during the test; therefore, its mass shall be verysmall to reduce the chance of molten metal burns. The fusewire shall be a copper wire with a diameter no greater than 0.02in. (0.0005 m).6.7 Electric SupplyThe electric supply should be suffi-cient to allow for the discharge of an electric arc with a gap ofup to 12 in. (0.305 m), with alternating arc current from 4000up to 25 000 A and with arc duration from 3 cyc
