GB 3836.15-2024 Explosive atmospheres — Part 15: Specification of electrical installations design, selection and erection
1 Scope
This document specifies the specific requirements for the design, selection, erection and initial inspection of electrical installations in, or associated with, explosive atmospheres.
This document is applicable to all electrical equipment including fixed, portable, transportable and personal, and installations.
This document is not applicable to:
— underground coal mine (the design, selection and installation of electrical installations in underground coal mine can refer to this document);
Note 1: See Safety Regulations for Coal Mine for specific requirements.
— inherently explosive situations and dust from explosives or pyrophoric substances (for example explosives manufacturing and processing);
— rooms used for medical purposes;
Note 2: Additional guidance on the requirements for hazards due to hybrid mixtures of dust or flyings and flammable gas or vapour is provided in Annex A.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 3836.1 Explosive atmospheres - Part 1: Equipment - General requirements
GB 3836.16 Explosive atmospheres - Part 16: Electrical installations inspection and maintenance
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 3836.1 and the following apply.
3.1 general
3.1.1
competent body
organization which can demonstrate appropriate technical knowledge and relevant skills to make the necessary assessments of the safety aspect under consideration
3.1.2
verification dossier
set of documents showing the compliance of electrical equipment and installations
3.1.3
electrical equipment
items applied as a whole or in part for the utilization of electrical energy
Note: These include, amongst others, items for the generation, transmission, distribution, storage, measurement, regulation, conversion and consumption of electrical energy and items for telecommunications.
3.2 hazardous areas
3.2.1
hazardous areas
area in which an explosive atmosphere is present, or may be expected to be present, in quantities such as to require special precautions for the construction, installation and use of equipment
Note: For the purposes of this document, an area is a three-dimensional region or space.
3.2.2
non-hazardous area
area in which an explosive atmosphere is not expected to be present in quantities such as to require special precautions for the construction, installation and use of equipment
3.2.3
equipment grouping
classification of electrical equipment related to the explosive atmosphere for which it is to be used
Note: Electrical equipment for use in explosive atmospheres is divided into three groups:
— Group I: electrical equipment for mines susceptible to firedamp;
— Group II (which can be divided into subgroups): electrical equipment for places with an explosive gas atmosphere, other than mines susceptible to firedamp;
— Group III (which can be divided into subgroups): electrical equipment for places with an explosive dust atmosphere.
3.2.4
hybrid mixture
mixture of a flammable gas or vapour with a combustible dust
3.2.5
maximum permissible surface temperature
highest temperature that a surface of electrical equipment is allowed to reach in practical service to avoid ignition
Note: This definition applies only to dust and does not apply to gases. The maximum permissible surface temperature will depend upon the type of dust, whether as a cloud or layer, including layer thickness and the application of a safety factor (see 5.4.3).
3.2.6
zones
hazardous areas classified into zones based upon the frequency of the occurrence and duration of an explosive atmosphere
3.2.7
zone 0
place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas or vapour is present continuously or for long periods or frequently
3.2.8
zone 1
place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas or vapour is likely to occur in normal operation occasionally
3.2.9
zone 2
place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas or vapour is not likely to occur in normal operation but, if it does occur, will persist for a short period only
3.2.10
zone 20
area in which an explosive atmosphere in the form of a cloud of dust in air is present continuously, or for long periods or frequently
3.2.11
zone 21
area in which an explosive atmosphere in the form of a cloud of dust in air is likely to occur, occasionally, in normal operation
3.2.12
zone 22
area in which an explosive atmosphere in the form of a cloud of dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only
3.3 flameproof enclosure “d”
type of protection in which the parts capable of igniting an explosive gas atmosphere are provided with an enclosure which can withstand the pressure developed during an internal explosion of an explosive mixture and which prevents the transmission of the explosion to the explosive gas atmosphere surrounding the enclosure
3.4 increased safety
3.4.1
increased safety “e”
type of protection applied to electrical equipment in which additional measures are applied so as to give increased security against the possibility of excessive temperatures and of the occurrence of arcs and sparks in normal service or under specified abnormal conditions
3.4.2
initial starting current
IA
highest r.m.s. value of current absorbed by an a.c. motor at rest or by an a.c. magnet with its armature clamped in the position of maximum air gap, when supplied at the rated voltage and rated frequency
3.4.3
time tE
time taken for an a.c. rotor or stator winding, when carrying the initial starting current IA, to be heated up to the limiting temperature from the temperature reached in rated service at the maximum ambient temperature
3.5 intrinsic safety
3.5.1
intrinsic safety “i”
type of protection based upon the restriction of electrical energy within the apparatus and of interconnecting wiring exposed to an explosive atmosphere to a level below that which can cause ignition by either sparking or heating effects
3.5.2
associated apparatus
electrical apparatus which contains both intrinsically safe circuits and non-intrinsically safe circuits and is constructed so that the non-intrinsically safe circuits cannot adversely affect the intrinsically safe circuits
Note: Associated apparatus may be either:
— electrical equipment which has another type of protection of non-intrinsic safety for use in the appropriate explosive atmosphere;
— electrical equipment not so protected and which, therefore, is not normally used within an explosive atmosphere.
3.5.3
intrinsically safe apparatus
electrical apparatus in which all the circuits are intrinsically safe
3.5.4
galvanic isolation
arrangement within an item of intrinsically safe apparatus or associated apparatus which permits the transfer of signals or power between two circuits without any direct electrical connection between the two
Note: Galvanic isolation frequently utilizes either magnetic (transformer or relay) or opto-coupled elements.
3.5.5
simple apparatus
electrical component or combination of components of simple construction with well-defined electrical parameters which is compatible with the intrinsic safety or energy-limited safety of the circuit in which it is used
3.5.6
intrinsically safe circuit
circuit in which any spark or any thermal effect produced in the conditions specified, which include normal operation and specified fault conditions, is not capable of causing ignition of a given explosive atmosphere
Note: The circuit may also contain associated apparatus.
Foreword II
Introduction VII
1 Scope
2 Normative references
3 Terms and definitions
4 General
5 Design and selection of electrical equipment
6 Equipment installation
7 Additional requirements
8 Initial inspection
Annex A (Informative) Hybrid mixtures
Annex B (Normative) Initial inspection – Equipment-specific inspection schedules
Annex C (Nominative) Potential stator winding discharge risk assessment – Ignition risk factors
Bibliography
