1、Designation: F2522 12 (Reapproved 2017)Standard 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 F2522; the number immediately following the designation indicate
2、s the year oforiginal adoption or, in the 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 determine the heat
3、 attenua-tion factor (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 t
4、he form of a shield 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-
5、m) diameter and 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 en
6、ergies (thermal-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 The values stated in inch-pound units are t
7、o be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand 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 a
8、ctual fire 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
9、, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Forspecific precautions, see Section 7.1.9 This international standard was dev
10、eloped in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Do
11、cuments2.1 ASTM Standards:2D4391 Terminology Relating to The Burning Behavior ofTextilesF1959/F1959M Test Method for Determining theArc Ratingof Materials for Clothing3. Terminology3.1 Definitions:3.1.1 arc, nconductive path in air for the electric currentcaused by ionization of air between two elec
12、trodes.3.1.2 arc duration, ntime duration of the 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, cmin.3.1.5 ar
13、c voltage, nvoltage across the gap caused by thecurrent flowing through the resistance created by the arc gap,V. See also Terminology D4391.1This test method is under the jurisdiction of ASTM Committee F18 onElectrical Protective Equipment for Workers and is the direct responsibility ofSubcommittee
14、F18.35 on Tools it includes a direct component and asymmetrical component, A.3.1.7 blowout, nthe extinguishing of the arc caused by amagnetic field.3.1.8 closure, npoint on supply current wave form wherearc is initiated.3.1.9 effective heat attenuation (EHAF)/cone of protection(COP) factor, nthe per
15、centage of the incident heat energythat is attenuated by the shield at the location of the worker.3.1.10 fragmentation, nmolten metal fragments or otherfragments emitted from an electric arc.3.1.11 heat attenuation factor (HAF), nthe percentage ofthe incident heat energy that is blocked by the safet
16、y shieldmaterial.3.1.12 heat flux, nthe thermal intensity indicated by theamount of energy transmitted divided by area and timeW/m2cal cm2s.3.1.13 i2t, nsum of the instantaneous arc current valuessquared multiplied by the incremental time values during thearc, A2/s.3.1.14 ignitability, n (ignitable,
17、 adj)in electric arcexposure, the property of a material involving ignition accom-panied by heat and light, and continued burning resulting inconsumption of at least 25 % of the exposed area of the testspecimen.3.1.15 ignition, nthe initiation of combustion.3.1.16 incident energy (Ei), nthe amount o
18、f energy (totalheat, cal/cm2) received at a surface as a direct result of anelectrical arc discharge as measured by temperature rise oncopper calorimeters.3.1.17 peak arc current, nmaximum value of the AC arccurrent, A.3.1.18 pressure wave, na certain force over an areacreated by air movement caused
19、 by an electric arc.3.1.19 RMS arc current, nroot mean square of the AC arccurrent, A.3.1.20 sensors, ncopper calorimeter, instrumented with athermocouple contained in a dielectric, heat protective housingfor use in measuring energy.3.1.21 shield mechanical strength value (SMS) factor,nthe mechanica
20、l ability of the shield to withstand the electricarc pressure wave and fragmentation.3.1.22 X/R ratio, nthe ratio of system inductive reactanceto resistance. It 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 cor
21、responds 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 shield material, the effective heat attenuationfactor (EHAF) at the location where the worker may be whileholding the hot stick or racking rod to
22、 which the shield isattached, and the shield mechanical strength (SMS). Thecopper calorimeters (incident energy monitoring sensors) areplaced for the HAF at the 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 exp
23、osed 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 shield to absorb and deflect the fragmentationshrapnel, not break or ignite, not to move from its attachment,and not to bend more then 20 degre
24、es.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 (blocked) by theshield is measured during exposure to an electric arc.4.3 The heat energy of the arc exposure is measured withcalorimeters.
25、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 test method isdetermined from the heat attenuation factor (in percent) at theshield location, and from the effective heat attenuation factor
26、 atthe worker location. The effective heat attenuation factor inpercent is the difference in the incident energy generated by thearc flash before and after the 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 incorp
27、orates incident heat energy moni-toring sensors.4.7 Further description of the shield reduction of the electricarc exposure on the worker is presented in Sections 12 and 13.5. Significance and Use5.1 This test method is intended for determining the heatattenuation factor (HAF) of a shield material a
28、nd the effectiveheat attenuation factor (EHAF) at the location of the worker.This can be obtained by measuring the reduction of the arcincident energy levels caused by a shield attached on a live linetool (hot stick) or on a racking rod and designed for protectionfor workers exposed to electric arcs
29、. 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 the variability of the arc exposure, differ-ent heat transmission values and pressure may result forindividual sensors. The results of each
30、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 involvemovement except that resulting from the exposure.5.3 This test method specifies a standard set of exposureconditions. Different exposure
31、conditions may produce differ-ent results.NOTE 1In addition to the standard set of exposure conditions, otherconditions representative of the expected hazard may be used and shall bereported should this data be cited.6. Apparatus6.1 General Arrangement for Determining Heat AttenuationFactor (HAF) of
32、 the ShieldThe test apparatus shall consist ofF2522 12 (2017)2supply bus, arc controller, recorder, arc electrodes, the shield,and incident energy monitoring sensors. The arc exposure inthe form of heat attenuation factor at the shield location shallbe monitored with two incident energy monitoring s
33、ensors.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 Fig. 1, except theshield is attached on the racking rod.6.2 General Arrangement for Determining Effective HeatAttenuation Fac
34、tor (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 sensors. The arc exposure in the form of effective heatattenuation factor at the location of the worker shall bemonitored with a
35、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 atthe same location as in the HAF tests (Figs. 1 and 2) and thesensors are located approximately 5 ft (1.52 m) from theelectric arc cent
36、er. 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.6.3 General Arrangement for Determining Shields Me-chanical Strength (SMS)The evaluation of shields mechani-cal strength value (SMS) is based on
37、 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 shield to withstand the electric arcpressure wave and fragmentation. The SMS value is deter-mined by observing the HAF tests for th
38、e 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 ElectrodesA typical arrangement of the arc electrodesis shown in Fig. 1. The arc shall be in a vertical position asshown.6.5 Electrode
39、sMake 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 Fuse WireA fuse wire, connecting the ends of oppos-ing electrodes tips, is used to initiate the arc. This wire isconsumed dur
40、ing 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 ga
41、p ofup to 12 in. (0.305 m), with alternating arc current from 4000up to 25 000 A and with arc duration from 3 cycles (0.05 s) upto 90 cycles (1.5 s) from a 60 Hz supply. The X/R ratio of thetest circuit shall be such that the test current contains a DCcomponent resulting in the first peak of the tes
42、t current havinga magnitude of 2.3 times the symmetrical RMS value.6.8 Test Circuit ControlRepeat exposures of the arc cur-rents shall not deviate more than 2 % per test from the selectedtest level. The make switch shall be capable of point on waveclosing within 0.2 cycles from test to test, such th
43、at the closingangle will produce maximum asymmetrical current with and1 = 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 rod above the floord4 = 24 in. (0.61 m), d
44、istance 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 5 ft (1.52 m) from the arc centerFIG. 1
45、Test Set-up for HAF Measurements with Shield on a Live Line ToolF2522 12 (2017)3X/R ratio of the test circuit as stated in 6.7. The arc current,duration, and voltage shall be measured. The arc, current,duration, voltage and energy shall be displayed in graph formand stored in digital format.d1 = 24
46、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 rod above the floord4 = 24 in. (0.61 m), distance of the shield from the electrodesd5=4in.(0.10m),vertical distance bet
47、ween 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. 2 Test Set-up for HAF Measurements with Shield on a Racking Rodd1 = 24 in. (0.6
48、1 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 cen
49、ters 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. 3 Test Set-up for EHAF Measurement with Shield on a Live Line ToolF2522 12 (2017)46.9 Data Acquisition SystemThe system shall be capableof recording voltage, current, and sufficient calorimeter outputsas required by the test. The sensitivity and accuracy of the dataacquisition system shall be as described in Test MethodF195
