DL/T 320-2019 PDF English (DL/T 320-2010: Older version)
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DL/T 320-2019: PDF in English (DLT 320-2019) DL/T 320-2019
DL
ELECTRIC POWER INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 13.340
C 73
Replacing DL/T 320-2010
Performance requirements of personal arc protective
equipment
ISSUED ON: JUNE 04, 2019
IMPLEMENTED ON: OCTOBER 01, 2019
Issued by: National Energy Administration
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 Technical requirements ... 9
5 Test methods ... 15
6 Selection methods ... 17
7 Quality inspection rules ... 17
8 Use and maintenance ... 20
9 Marking, instructions for use, storage and transportation ... 21
Appendix A (Informative) Arc burn ... 22
Appendix B (Informative) Conversion to imperial units of arc hazard energy ... 23
Appendix C (Informative) Figures of personal arc protective equipment ... 24
Appendix D (Normative) Risk assessment of arc hazard ... 28
Appendix E (Informative) Arc hazard energy calculation methods and examples ... 30
Bibliography ... 39
Performance requirements of personal arc protective
equipment
1 Scope
This Standard specifies the technical requirements, test methods, selection methods,
quality inspection rules, use and maintenance as well as marking, instructions for use,
storage and transportation of personal arc protective equipment in electrical workplaces.
This Standard applies to the production, acceptance and use of personal arc protective
equipment in the electric power trade.
2 Normative references
The following referenced documents are indispensable for the application of this
document. For dated references, only the dated version applies to this document. For
undated references, the latest edition (including all amendments) applies to this
document.
GB/T 2912.1, Textiles - Determination of formaldehyde - Part 1: Free and
hydrolyzed formaldehyde (water extraction method)
GB/T 3609.1-2008, Occupational eye and face protection - Welding protection - Part
1: Welding protector
GB/T 3917.3, Textiles - Tear properties of fabrics - Part 3: Determination of tear
force of trapezoid-shaped test specimens
GB/T 3920, Textiles - Tests for colour fastness - Colour fastness to rubbing
GB/T 3922, Textiles - Tests for colour fastness - Colour fastness to perspiration
GB/T 3923.2, Textiles - Tensile properties of fabrics - Part 2: Determination of
maximum force using the grab method
GB/T 4669-2008, Textiles - Woven fabrics - Determination of mass per unit length
and mass per unit area
GB/T 5455, Textiles - Burning behaviour - Determination of damaged length,
afterglow time and afterflame time of vertically oriented specimens
GB/T 5713, Textiles - Tests for colour fastness - Colour fastness to water
3.3
arc burn
Compound burns to the human body – caused by the powerful arc light generated when
electric current passes through the air medium or the circuit is short-circuited – within
its injuring distance. Thermal burn caused by arc flash and electrical burn caused when
electric current breaks down and enters the human body are included. See Appendix A
for grading of burn severity. This Standard applies to the prevention of thermal burn.
3.4
arc protection
Protection which is taken – when an arc occurs, by blocking the incident arc hazard
energy – to reduce the possible harm of the arc to the human body, so that the residual
energy is not enough to cause second-degree or above burns to the human body.
3.5
arc thermal performance value; ATPV
Value characterized by 50% chance that the energy incident on the arc protection
material will cause heat energy to penetrate the material and cause second-degree burns
(judged based on the Stohr curve). When the external incident energy is less than this
value, the material can effectively block and reduce the transmitted energy to avoid
causing second-degree and above burns to the human body.
3.6
breakopen threshold energy
Ebt
Value characterized by that the energy incident on a single-layer or multi-layer arc
protection fabric has a 50% chance of causing the fabric to rupture. During the arc
protection performance test, where the total area of holes produced in the arc protection
fabric exceeds 160 mm2 or the length of a single hole is greater than 25 mm, it is a
rupture. For multi-layer arc protection fabrics, holes shall penetrate all layers of fabrics.
3.7
inherent flame resistant
Flame retardant and heat insulation property – formed relying on the molecular
structure of the protective material itself – whose corresponding property does not
decline as conditions change.
3.8
after-finishing flame resistant
Certain flame retardant and heat insulation property of the material – obtained through
dyeing and finishing methods using a certain dose of chemicals – whose corresponding
property decreases or disappears as conditions change.
3.9
personal arc protective equipment
Protective equipment used to protect the persons who may be exposed to arc-related
thermal hazards, including arc protective garment, arc protective face shield, arc
protective hood, arc protective gloves, and arc protective shoes cover.
3.10
arc protective garment
Protective equipment used to protect the torso, arms, and legs of persons who may be
exposed to arc-related thermal hazards.
3.11
arc protective face shield
Protective equipment used to protect the eyes and face of persons who may be exposed
to arc-related thermal hazards.
3.12
arc protective hood
Protective equipment used to protect the head and neck of persons who may be exposed
to arc-related thermal hazards.
3.13
arc protective gloves
Protective equipment used to protect the hands of persons who may be exposed to arc-
related thermal hazards.
3.14
arc protective shoes cover
Protective equipment used to protect the feet of persons who may be exposed to arc-
related thermal hazards.
a) Vertical burning behaviour. The vertical burning behaviour of the single layer or
each layer of the multi-layer fabrics shall be tested according to the method
specified in GB/T 5455. During the test, the fabric shall not melt and drop, the
damaged length shall not be greater than 100 mm, and the afterflame time shall
not be greater than 2 s.
b) Flame retardant durability performance. The flame-retardant durability of the
single layer or each layer of the multi-layer fabrics shall be tested by washing 100
times according to the washing method specified in GB/T 17595 (temperature
40 °C), and the method specified in GB/T 5455. During the test, the fabric shall
not melt and drop, the damaged length shall not be greater than 100 mm, and the
afterflame time shall not be greater than 2 s.
4.1.1.3 Physical and chemical safety performance
Protective fabrics shall be provided with the following physical and chemical safety
properties:
a) Conductive loops shall not be formed on the fabrics.
b) The formaldehyde content of fabrics – measured according to the method
specified in GB/T 2912.1 – shall meet the requirements of Table 2.
c) The pH value of fabrics – measured according to the method specified in GB/T
7573 – shall meet the requirements of Table 2.
d) The colour fastness to water of fabrics – tested according to the method specified
in GB/T 5713 – shall meet the requirements of Table 2.
e) The color fastness to acid and alkali perspiration of fabrics – tested according to
the method specified in GB/T 3922 – shall meet the requirements of Table 2.
f) The color fastness to dry rubbing of fabrics – tested according to the method
specified in GB/T 3920 – shall meet the requirements of Table 2.
g) When the color fastness to household and commercial laundering of the single
layer and outer shell material of the multi-layer fabrics is tested according to the
method specified in GB/T 12490, where the test condition is 50 °C water
temperature for 45 minutes, the color change grade of the fabrics shall meet the
requirements of Table 2.
h) The odor detection of fabrics – tested according to the method specified in 6.7 of
GB 18401-2010 – shall meet the requirements of Table 2.
i) The decomposable aromatic amine dyes of fabrics – tested according to the
methods specified in GB/T 17592 and GB/T 23344 – shall meet the requirements
of Table 2.
The design and performance of arc protective gloves (referred to as gloves) and arc
protective shoes cover (referred to as shoes cover) shall comply with the requirements
in Table 7.
5 Test methods
5.1 Fabric arc protection performance test
5.1.1 Test sample and preparation
5.1.1.1 Requirements for test sample
Before testing the arc protection performance of fabrics, ensure that the fabrics pass the
flame-retardant property test.
5.1.1.2 Preparation steps
The fabric sample to be tested shall be washed and dried three times. The washing water
temperature shall be 50 °C and the sample shall be tumble dried. The size of the test
sample shall be 30 cm × 66 cm. Take enough samples and the number shall not be less
than 33 pieces. Multi-layer fabric samples shall be arranged in order and the upper ends
of the multi-layer fabrics shall be sewn or stapled into a whole before testing. Place the
prepared samples in groups of 3 vertically on the corresponding 3 sample racks. Each
sample rack shall have two monitoring sensors located on both sides of the sample rack;
the three sample racks shall be evenly distributed on a circle at 120° intervals. The upper
and lower electrodes under test are located at the center of the circle, and the distance
between the upper and lower electrodes is 30.5 cm. The test arc peak current is 8 kA ±
1 kA.
5.1.2 Test process
5.1.2.1 Requirements for the number of samples and valid data points
For ATPV testing of fabric samples, at least 7 groups of samples shall be used. During
the test, different incident energies are obtained by adjusting the arc duration. During
the ATPV calculation, the number of valid data points for incident energy shall not be
less than 21.
5.1.2.2 Requirements for the placement of data points
Among at least 21 data points, at least 15% of the data points shall fall in the first area,
where the incident energy value shall make the energy received by the sensor
corresponding to the sample reach second-degree burn1); in addition, at least 15% of
the data points shall fall in the second area, where the incident energy value shall make
the energy received by the sensor corresponding to the sample not reach second-degree
burn1); in addition, at least 50% of the data points shall fall in the third area, where some
of the incident energy values shall reach second-degree burns1), and some shall not
reach second-degree burns. These values are distributed within the range of ±20% of
the sample ATPV.
5.1.3 Data processing
The ATPV shall be determined by regression analysis calculations from all measured
data points.
5.2 Face shield arc protection performance test
5.2.1 Face shield material arc protection performance test
The face shield material arc protection performance test shall be carried out on at least
24 material samples. During the test, a group of 3 samples to be tested is placed on the
corresponding 3 standard prosthetic heads; each standard prosthetic head has 4 built-in
sensors, located respectively in the eyes, mouth and chin; on both sides of each
prosthetic head there is a monitoring sensor; three standard prosthetic heads are evenly
distributed on a circle at 120°. The upper and lower electrodes under test are located at
the center of the circle, and the distance between the upper and lower electrodes is 30.5
cm. The arc peak current required for the test is 8 kA ± 1 kA. Its testing process and
data processing methods are consistent with 5.1.
5.2.2 Evaluation and verification of overall protection performance of head shield
and hood
The evaluation and verification of the overall protection performance of face shield and
hood shall be carried out on products manufactured with the face shield that meets the
requirements of Table 3. Take 3 samples from each group and determine them in turn
according to the method in 5.2.1. If no less than 2 samples in each group of samples are
qualified, the group shall be considered as passed; otherwise, another group of samples
shall be taken, up to 8 groups of samples. The overall protection performance of the
face shield and hood shall not be lower than the arc protection performance value of the
face shield.
1) According to Stohr curve.
c) Dirt shall be removed from personal arc protective equipment in a timely manner
after use.
8.3 Instructions for forbidden
Instructions for forbidden are as follows:
a) Personal arc protective equipment which is damaged and cannot be repaired shall
be prohibited from use;
b) Personal arc protective equipment after arc burns shall be prohibited from use.
9 Marking, instructions for use, storage and transportation
9.1 Marking
The marking shall include the following:
a) name;
b) implementation standard number;
c) ATPV, Ebt and mass per unit area of fabrics;
d) name, trademark, address and contact number of the manufacturer or supplier;
e) model specifications;
f) date of delivery;
g) storage conditions or corresponding illustrations.
9.2 Instructions for use
Instructions for use shall at least include correct use, care and maintenance methods.
9.3 Storage
The product shall be stored in a dry and ventilated place, away from direct sunlight, and
must not be mixed with corrosive items.
9.4 Transportation
The product shall be kept clean during transportation and must not be damaged in
packaging, stressed, damaged, damp or exposed to direct sunlight.
Appendix A
(Informative)
Arc burn
A.1 Classification of arc burns
The severity of arc burns depends on the scope and depth of the injured tissue. The
depth of burns is divided into first-degree, second-degree (superficial partial-thickness
burns and deep partial-thickness burns) and third-degree burns according to the
internationally accepted rule of three degrees and four levels.
A.2 First-degree burns
First-degree burns are limited to the epidermis, with skin congestion and mild local
swelling and pain. The basal cell layer is not damaged, and is of active regeneration
ability; no scars are left after healing; it is not included in the burn area.
A.3 Second-degree burns
Second-degree burns are classified into superficial partial-thickness burns and deep
partial thickness burns. Superficial partial-thickness burns include damage to the entire
thickness of the epidermis and the papillary layer of the dermis, while retaining the hair
follicles, sebaceous glands and sweat glands, and leaving the reticular layer intact.
Blisters are formed between the epidermis and the dermis. The base is red and moist,
the peripheral nerves are injured, and the pain is severe. There is generally no scar left
after healing, and sometimes there is pigmentation. Deep partial-thickness burns have
involved the reticular layer of the dermis, but the deep hair follicles are intact; there is
dull sensation, but there is hair-pulling pain; the base is slightly moist, and the wound
surface is pale or white with red, red and white alternately; healing takes a long time,
but the adnexal epithelium can proliferate, leaving scars if granulation tissue grows
during the healing period.
A.4 Third-degree burns
Third-degree burns damage the entire thickness of the skin and may also involve
subcutaneous tissue, muscles, bones, etc. The local symptoms are pale, tan or burnt
black; the skin loses elasticity, and is as hard as leather to the touch; the surface is dry;
the pain disappears, and there is no hair-pulling pain. Smaller wounds are healed by the
crawling of edge epithelial cells, but there are severe scars; larger wounds must be
repaired by skin grafting and transfer of skin flaps.
Appendix D
(Normative)
Risk assessment of arc hazard
D.1 Assessment significance
Arc hazard risk assessment is the study of the risk of arc injury when a circuit (including
its protective devices) is short-circuited. The study results of circuit short circuit are
used to determine the short circuit fault current. The study results of the short-circuit
protective device are used to determine the arcing time. The study results coordinating
circuit short circuits and their protective devices provide the information needed for
risk assessment of arc hazards. The results of arc hazard risk assessment are used to
identify arc protection interfaces (risk characterization) and incident energy (risk
estimation) within specified operating distances at any location or level throughout the
generation, transmission, distribution, or consumption system.
The arc protection interface and incident energy, once calculated, can be used as a
reference for selecting the level of personal arc protective equipment, cutting off power
for work or using arc-proof switching equipment, and other necessary engineering
measures or work practices.
D.2 Assessment steps
The risk assessment steps of arc hazards are as follows:
a) Collect system and equipment parameter data. Collect system circuit diagrams,
including parameters of transformers, transmission lines, loop distribution,
protective devices, capacitors, circuit breakers with protective devices, voltage
levels and each component, etc.
b) Determine the operating mode of system. In addition to the system parameters,
the short-circuit fault current is also affected by the way the system is operated,
for example, the system containing one or more branch lines, the standby busbar
circuit breaker switching status, the generator in use or on standby, etc.
c) Calculate the short circuit fault current. Based on the system wiring diagram,
calculate the short-circuit fault current.
d) Calculate the arc current. According to the corresponding conditions, select the
calculation formula including the one introduced in Appendix E to calculate the
arc current.
Appendix E
(Informative)
Arc hazard energy calculation methods and examples
E.1 Overview
Calculate the estimated possible arc hazard energy based on known system voltage,
fault current, arc duration, and operating distance in a typical work area.
E.2 Arc hazard energy calculation methods
E.2.1 Empirical calculation model
E.2.1.1 Overview
The empirical calculation model is suitable for situations where the frequency is 50 Hz,
the system voltage is 380 V ~ 15 kV, the short-circuit fault current is 700 A ~ 106 000
A, and the conductor gap is 13 mm ~ 152 mm. The calculation steps are:
a) Calculate the arc current Ia;
b) Calculate the typical accident energy En;
c) Calculate the accident energy E.
E.2.1.2 Calculate the arc current Ia
The arc current is calculated using Formula (E.1):
Where:
Ia – arc current, kA;
K – constant, which is 0.153 for open structure, and 0.097 for closed structure;
Ik – short circuit fault current, kA;
U – system voltage, kV;
G – conductor gap, mm, see Table E.1.
The system arc current of 1 kV and above is calculated using Formula (E.2):
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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