ASTM F2522-05(2011)
(Test Method)Standard Test Method for Determining the Protective Performance of a Shield Attached on Live Line Tools or on Racking Rods for Electric Arc Hazards
Standard Test Method for Determining the Protective Performance of a Shield Attached on Live Line Tools or on Racking Rods for Electric Arc Hazards
SCOPE
1.1 This test method is used to determine the heat attenuation factor (HAF), the effective heat attenuation factor (EHAF), and the shields mechanical strength (SMS) of a shield attached on live line tools or racking rods intended for protection of workers exposed to electric arcs.
1.2 The materials used in this test method of worker protection are in the form of a shield attached on live line tools or on the racking rods.
1.3 The protective shield described in this test method shall be transparent and shall be easily attached and removed from live line tools or from racking rods.
1.4 The protective shield described in this test method has 24-in. (0.61-m) diameter and can be used for most applications, however for special cases, the shield can have different sizes to suit the protective requirements of the application.
1.5 This standard shall be used to measure and describe the properties of materials, products, or assemblies in response to incident energies (thermal-convective, and radiant and pressure wave) generated by an electric arc under controlled laboratory conditions and does not purport to predict damage from light, resultant pressure impact other than the pressure and thermal aspects measured.
1.6 UnitsThe values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.7 This standard shall not be used to describe or appraise the fire hazard or fire risk of materials, products, or assemblies under actual fire conditions. However, results of this test may be used as elements of a fire assessment, which takes into account all of the factors, which are pertinent to an assessment of the fire hazard of a particular end use.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautions, see Section .
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Designation: F2522 − 05(Reapproved 2011)
Standard Test Method for
Determining the Protective Performance of a Shield
Attached on Live Line Tools or on Racking Rods for Electric
Arc Hazards
This standard is issued under the fixed designation F2522; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.8 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method is used to determine the heat attenua-
responsibility of the user of this standard to establish appro-
tionfactor(HAF),theeffectiveheatattenuationfactor(EHAF),
priate safety and health practices and determine the applica-
and the shields mechanical strength (SMS) of a shield attached
bility of regulatory limitations prior to use. For specific
on live line tools or racking rods intended for protection of
precautions, see Section 7.
workers exposed to electric arcs.
1.2 The materials used in this test method of worker
2. Referenced Documents
protection are in the form of a shield attached on live line tools
2.1 ASTM Standards:
or on the racking rods.
D4391 Terminology Relating to The Burning Behavior of
1.3 The protective shield described in this test method shall
Textiles
be transparent and shall be easily attached and removed from
F1959/F1959M TestMethodforDeterminingtheArcRating
live line tools or from racking rods.
of Materials for Clothing
1.4 The protective shield described in this test method has
3. Terminology
24-in.(0.61-m)diameterandcanbeusedformostapplications,
however for special cases, the shield can have different sizes to 3.1 Definitions:
suit the protective requirements of the application.
3.1.1 arc, n—conductive path in air for the electric current
caused by ionization of air between two electrodes.
1.5 This standard shall be used to measure and describe the
properties of materials, products, or assemblies in response to 3.1.2 arc duration, n—time duration of the arc, s.
incidentenergies(thermal-convective,andradiantandpressure
3.1.3 arc energy, vi dt, n—sum of the instantaneous arc
wave) generated by an electric arc under controlled laboratory
voltage values multiplied by the instantaneous arc current
conditions and does not purport to predict damage from light,
values multiplied by the incremental time values during the
resultant pressure impact other than the pressure and thermal
arc, J.
aspects measured.
3.1.4 arc gap, n—distance between the arc electrodes.
1.6 The values stated in inch-pound units are to be regarded
3.1.5 arc voltage, n—voltage across the gap caused by the
as standard. The values given in parentheses are mathematical
current flowing through the resistance created by the arc gap,
conversions to SI units that are provided for information only
V. See also Terminology D4391.
and are not considered standard.
3.1.6 asymmetrical arc current, n—the total arc current
1.7 This standard shall not be used to describe or appraise
produced during closure; it includes a direct component and a
the fire hazard or fire risk of materials, products, or assemblies
symmetrical component, A.
under actual fire conditions. However, results of this test may
3.1.7 blowout, n—the extinguishing of the arc caused by a
be used as elements of a fire assessment, which takes into
magnetic field.
account all of the factors, which are pertinent to an assessment
3.1.8 closure, n—point on supply current wave form where
of the fire hazard of a particular end use.
arc is initiated.
This test method is under the jurisdiction of ASTM Committee F18 on
Electrical Protective Equipment for Workers and is the direct responsibility of
Subcommittee F18.35 on Tools and Equipment. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2011. Published September 2011. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2005. Last previous edition approved in 2005 as F2522-05. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/F2522-05R11. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2522 − 05 (2011)
3.1.9 delta peak temperature, n—difference between the EHAF test at the probable location of the worker’s hand, head,
maximum temperature and the initial temperature of the sensor side of the face, chest, and legs when exposed to the heat
during the test, °C. energy from a controlled electric arc. The SMS value of the
shield is obtained from visual observations of the HAF test for
3.1.10 effective heat attenuation (EHAF)/cone of protection
the ability of the shield to absorb and deflect the fragmentation
(COP) factor, n—the percentage of the incident heat energy
shrapnel, not break or ignite, not to move from its attachment,
that is attenuated by the shield at the location of the worker.
and not to bend more then 20 degrees.
3.1.11 fragmentation, n—molten metal fragments or other
4.2 During HAF and EHAF tests, the center of the shield is
fragments emitted from an electric arc.
aligned with the mid point of the arc gap. During this
3.1.12 heat attenuation factor (HAF), n—the percentage of
procedure, the amount of heat energy reduced (blocked) by the
the incident heat energy that is blocked by the safety shield
shield is measured during exposure to an electric arc.
material.
4.3 The heat energy of the arc exposure is measured with
3.1.13 heat flux, n—the thermal intensity indicated by the
calorimeters. The rate at which the temperature of the calorim-
amount of energy transmitted divided by area and time
2 2 eters increases is a direct measure of the heat energy received.
W/m [cal/cm s].
4.4 Theshieldprotectiveperformanceforthistestmethodis
3.1.14 i t, n—sum of the instantaneous arc current values
determined from the heat attenuation factor (in percent) at the
squared multiplied by the incremental time values during the
shield location, and from the effective heat attenuation factor at
arc, A /s.
the worker location. The effective heat attenuation factor in
3.1.15 ignitability, n (ignitable, adj)—in electric arc expo-
percentisthedifferenceintheincidentenergygeneratedbythe
sure, the property of a material involving ignition accompanied
arc flash before and after the shield was used.
by heat and light, and continued burning resulting in consump-
4.5 Heat transfer data can be used to predict the onset of
tion of at least 25 % of the exposed area of the test specimen.
second degree burn using the Stoll curve.
3.1.16 ignition, n—the initiation of combustion.
4.6 This procedure incorporates incident heat energy moni-
3.1.17 incident energy (E), n—the amount of energy (total
i
2 toring sensors.
heat, cal/cm ) received at a surface as a direct result of an
electrical arc discharge as measured by temperature rise on 4.7 Further description of the shield reduction of the electric
copper calorimeters. arc exposure on the worker is presented in Sections 12 and 13.
3.1.18 peak arc current, n—maximum value of the AC arc
5. Significance and Use
current, A.
5.1 This test method is intended for determining the heat
3.1.19 pressure wave, n—a certain force over an area
attenuation factor (HAF) of a shield material and the effective
created by air movement caused by an electric arc.
heat attenuation factor (EHAF) at the location of the worker.
3.1.20 RMS arc current, n—root mean square of theAC arc
This can be obtained by measuring the reduction of the arc
current, A.
incident energy levels caused by a shield attached on a live line
3.1.21 sensors, n—copper calorimeter, instrumented with a
tool (hot stick) or on a racking rod and designed for protection
thermocouple contained in a dielectric, heat protective housing
for workers exposed to electric arcs. The shield mechanical
for use in measuring energy.
strength(SMS)canbeobtainedfromvisualobservationsofthe
3.1.22 shield mechanical strength value (SMS) factor, high speed video recordings of each shot during HAF tests.
n—the mechanical ability of the shield to withstand the electric 5.1.1 Because of the variability of the arc exposure, differ-
arc pressure wave and fragmentation. ent heat transmission values and pressure may result for
individual sensors. The results of each sensor are evaluated in
3.1.23 time to delta peak temperature, n—the time from
accordance with Section 12.
beginning of the initiation of the arc to the time the delta peak
temperature is reached, s.
5.2 This test method maintains the shield and the heat
sensors in a static, vertical position and does not involve
3.1.24 X/R ratio, n—the ratio of system inductive reactance
movement except that resulting from the exposure.
toresistance.ItisproportionaltotheL/Rratiooftimeconstant,
and is, therefore, indicative of the rate of decay of any DC
5.3 This test method specifies a standard set of exposure
offset. A large X/R ratio corresponds to a large time constant
conditions. Different exposure conditions may produce differ-
and a slow rate of decay.
ent results.
NOTE 1—In addition to the standard set of exposure conditions, other
4. Summary of Test Method
conditions representative of the expected hazard may be used and shall be
reported should this data be cited.
4.1 This test method determines the heat attenuation factor
(HAF) of the shield material, the effective heat attenuation
6. Apparatus
factor (EHAF) at the location where the worker may be while
holding the hot stick or racking rod to which the shield is 6.1 GeneralArrangement for Determining HeatAttenuation
attached, and the shield mechanical strength (SMS). The Factor (HAF) of the Shield—The test apparatus shall consist of
copper calorimeters (incident energy monitoring sensors) are supply bus, arc controller, recorder, arc electrodes, the shield,
placed for the HAF at the shield (front and back), and for the and incident energy monitoring sensors. The arc exposure in
F2522 − 05 (2011)
the form of heat attenuation factor at the shield location shall 6.4 Electrodes—Atypical arrangement of the arc electrodes
be monitored with two incident energy monitoring sensors. is shown in Fig. 1. The arc shall be in a vertical position as
Figs. 1 and 2 show the test set-up and the location of the shield shown.
on the hot stick and on the racking rod and the location of
6.5 Electrodes—Make the electrodes from electrical grade
sensors. Fig. 2 has the same test set-up as Fig. 1, except the
copper (alloy type 110) rod of a nominal ⁄4-in. (0.019-m)
shield is attached on the racking rod.
diameter. Lengths of 18 in. (0.460 m) long have been found to
6.2 General Arrangement for Determining Effective Heat
be adequate.
Attenuation Factor (EHAF) at the Location of the Worker—
6.6 Fuse Wire—A fuse wire, connecting the ends of oppos-
The test apparatus shall consist of supply bus, arc controller,
ing electrodes tips, is used to initiate the arc. This wire is
recorder, arc electrodes, a shield, and incident energy monitor-
consumed during the test; therefore, its mass shall be very
ing sensors. The arc exposure in the form of effective heat
small to reduce the chance of molten metal burns. The fuse
attenuation factor at the location of the worker shall be
wireshallbeacopperwirewithadiameternogreaterthan0.02
monitored with a minimum of six incident energy monitoring
in. (0.0005 m).
sensors. Figs. 3 and 4 show the test set-up and the location of
6.7 Electric Supply—The electric supply should be suffi-
the shield and the sensors. The shield for the EHAF test is at
the same location as in the HAF tests (Figs. 1 and 2) and the cient to allow for the discharge of an electric arc with a gap of
up to 12 in. (0.305 m), with alternating arc current from 4000
sensors are located approximately 5 ft (1.52 m) from the
up to 25 000Aand with arc duration from 3 cycles (0.05 s) up
electric arc center. Fig. 4 has the same test set-up as Fig. 3,
to 90 cycles (1.5 s) from a 60 Hz supply. The X/R ratio of the
except the shield in Fig. 4 is attached on the racking rod, and
test circuit shall be such that the test current contains a DC
in Fig. 3 the shield is attached on a hotstick.
component resulting in the first peak of the test current having
6.3 General Arrangement for Determining Shield’s Me-
a magnitude of 2.3 times the symmetrical RMS value.
chanical Strength (SMS)—The evaluation of shield’s mechani-
cal strength value (SMS) is based on visual observations of the 6.8 Test Circuit Control—Repeat exposures of the arc cur-
high speed video recordings of the arc tests made in 6.1 (HAF rents shall not deviate more than 2 % per test from the selected
tests). The purpose of the SMS test is to determine the test level. The make switch shall be capable of point on wave
mechanical ability of the shield to withstand the electric arc closing within 0.2 cycles from test to test, such that the closing
pressure wave and fragmentation. The SMS value is deter- angle will produce maximum asymmetrical current with an
mined by observing the HAF tests for the ability of the shield X/R ratio of the test circuit as stated in 6.7. The arc current,
to absorb and deflect the fragmentation shrapnel, not break or duration, and voltage shall be measured. The arc, current,
ignite, not to move from its attachment, and not to bend more duration, voltage and energy shall be displayed in graph form
then 20 degrees. and stored in digital format.
d1 = 24 in. (0.61 m), distance from the wall (back plate) to the arc electrodes
d2=6in.(0.15m)(gap) between electrodes
d3 = 53 in. (1.35 m), parallel distance of the hot stick or the racking rod above the floor
d4 = 24 in. (0.61 m), distance of the shield from the electrodes
d5=4in.(0.10m),vertical distance between centers of S’1 and S’2
S’1 and S’2 = 24.5 in. (0.62 m), approximate horizontal distance of the sensors from the electrodes
S1, S2, S3, S4, S5, and S6 are located vertically, and S1 is 5 ft (1.52 m) from the arc center
FIG. 1 Test Set-up for HAF Measurements with Shield on a Live Line Tool
F2522 − 05 (2011)
d1 = 24 in. (0.61 m), distance from the wall (back plate) to the arc electrodes
d2=6in.(0.15m)(gap) between electrodes
d3 = 53 in. (1.35 m), parallel distance of the hot stick or the racking rod above the floor
d4 = 24 in. (0.61 m), distance of the shield from the electrodes
d5=4in.(0.10m),vertical distance between centers of S’1 and S’2
S’1 and S’2 = 24.5 in. (0.
...
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