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This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization—Part 1: Rules for the structure and drafting of standardizing documents.
This is Part 9 of GB/T 3836 Explosive atmospheres. The following parts of GB/T 3836 have been published:
——Part 1: Equipment—General requirements;
——Part 2: Equipment protection by flameproof enclosures “d”;
——Part 3: Equipment protection by increased safety “e”;
——Part 4: Equipment protection by intrinsic safety "i";
——Part 5: Equipment protection by pressurized enclosure “p”;
——Part 6: Equipment protection by oil immersion “o”;
——Part 7: Equipment protection by powder filling “q”;
——Part 8: Equipment protection by type of protection “n”;
——Part 9: Equipment protection by type of protection “m”;
——Part 11: Material characteristics for gas and vapour classification—Test methods and data;
——Part 12: Material characteristics for combustible dusts—Test methods;
——Part 13: Equipment repair, overhaul and reclamation;
——Part 14: Classification of areas - Explosive gas atmosphere;
——Part 15: Electrical installations design, selection and erection;
——Part 16: Electrical installations inspection and maintenance;
——Part 17: Equipment protection by pressurized room “p” and artificially ventilated room “v”;
——Part 18: Intrinsically safe electrical systems;
——Part 20: Equipment with equipment protection level (EPL) Ga;
——Part 21: Application of quality systems for equipment manufacture;
——Part 22: Protection of equipment and transmission system using optical radiation;
——Part 23: Group I, category EPL Ma equipment intended to remain functional in atmospheres endangered by firedamp and/or coal dust;
——Part 24: Equipment protection by special protection “s”;
——Part 25: Requirements for process sealing between flammable process fluids and electrical systems;
——Part 26: Electrostatic hazards—Guidance;
——Part 27: Electrostatic hazards—Test;
——Part 28: Non-electrical equipment for potentially explosive atmospheres—Basic method and requirements;
——Part 29: Non-electrical equipment for explosive atmospheres—Constructional safety “c”, control of ignition source “b”, liquid immersion “k”;
——Part 30: Equipment and components in explosive atmospheres in underground mines;
——Part 31: Equipment dust ignition protection by enclosure “t”;
——Part 32: Intrinsically safe systems with electronically controlled spark duration limitation;
——Part 33: Equipment in adverse service conditions;
——Part 34: Equipment assemblies;
——Part 35: Classification of areas for explosive dust atmospheres;
This document replaces GB 3836.9-2014 Explosive atmospheres—Part 9: Equipment protection by type of protection “m” and GB 12476.6-2010 Electrical apparatus for use in the presence of combustible dust—Part 6: Protection by encapsulation “mD”. This document is developed by reference to GB 3836.9-2014 and integrates the contents of GB 12476.6-2010. In addition to structural adjustment and editorial changes, the following main technical changes have been made with respect to GB 3836.9-2014:
——Additional requirements for level of protection “ma” are added (see 4.2 hereof);
——The thermal conductivity requirements in the technical description are added (see 5.2 hereof);
——The options for determining infallible and separating components in a fault are added (see 7.2 hereof);
——The dimension diagram of compound thickness is modified (see 7.4.1 hereof; 7.4.1 of Edition 2014);
——The standard options for rigid and multi-layer printed wiring boards with through connections are added (see 7.4.3.1 hereof);
——The additional requirements for batteries are modified and added (see 7.8.3 hereof; 7.8.3 of Edition 2014);
——The requirements for two protective devices with level of protection "ma” are added (see 7.9.2 hereof);
——The requirements for two thermal protective devices with level of protection "mb” are added (see 7.9.3 hereof);
——The limit of 2/3 rated voltage of resettable thermal protective devices with switching contacts is deleted (see 7.9.3 of Edition 2014);
——The requirements for measuring the maximum surface temperature of level of protection “Da” are added (see 8.2.2 hereof);
——The reference service temperature of thermal endurance test is modified (see 8.2.3.1 hereof; 8.2.3.1 of Edition 2014);
——The option of dielectric strength type test is added (see 8.2.4.1 hereof);
——The alternative methods for pressure test of "mb" equipment are added (see 8.2.6);
——The requirements for the number of samples used in sealing test for built-in protective devices and methods for reducing samples are added (see 8.2.8 hereof);
——Different cases of routine dielectric strength test are added (see 9.2 hereof);
——The dielectric strength test requirements between circuit and environment are added (see Annex C hereof).
This document has been redrafted and modified in relation to IEC 60079-18: 2014, Explosive atmospheres—Part 18: Equipment protection by encapsulation “m”.
The main technical differences with respect to IEC 60079-18: 2014 and their reasons are as follows:
——The adjustments on technical differences have been made for the normative references of this document to adapt to the technical conditions in China, which are mainly reflected in Clause 2 "Normative references”, with the following specific content:
● IEC 60243-1 is replaced by GB/T 1408.1 which is identical to the international standard (see 5.2 hereof);
● IEC 60079-0 is replaced by GB/T 3836.1 which is modified in relation to the international standard (see Clause 1 hereof);
● IEC 60079-7 is replaced by GB/T 3836.3 which is modified in relation to the international standard (see 7.2.2 hereof);
● IEC 60079-11 is replaced by GB/T 3836.4 which is modified in relation to the international standard (see 7.2.2 hereof);
● IEC 60079-15 is replaced by GB/T 3836.8 which is modified in relation to the international standard (see 7.5.2 hereof);
● IEC 60079-26 is replaced by GB/T 3836.20 which is modified in relation to the international standard (see 7.6.2 hereof);
● IEC 60079-31 is replaced by GB/T 3836.31 which is modified in relation to the international standard (see 7.6.2 hereof);
● IEC 60738-1 is replaced by GB/T 7153 which is identical to the international standard (see 7.9.3 hereof);
● IEC 60691 is replaced by GB/T 9816.1 which is modified in relation to the international standard (see 7.8.5 hereof);
● IEC 60730-2-9 is replaced by GB/T 14536.10 which is identical to the international standard (see 7.9.3 hereof);
● IEC 61140 is replaced by GB/T 17045 which is identical to the international standard (see 7.2.3 hereof);
● IEC 61558-1 is replaced by GB/T 19212.1 which is modified in relation to the international standard (see 7.2.3 hereof);
● IEC 61558-2-6 is replaced by GB/T 19212.7 which is identical to the international standard (see 7.2.3 hereof);
● IEC 60127 (all parts) series are replaced by GB/T 9364 (all parts) (see 7.8.5 hereof), and the degree of consistency between various parts of the two standards is as follows:
◆ GB/T 9364.1-2015 Miniature fuses—Part 1: Definitions for miniature fuses and general requirement for miniature fuse-links (IEC 60127-1: 2006, MOD);
◆ GB/T 9364.2-2018 Miniature fuses—Part 2: Cartridge fuse-links (IEC 60127-2: 2014, MOD);
◆ GB/T 9364.3-2018 Miniature fuses—Part 3: Sub-miniature fuse-links (IEC 60127-3: 2015, MOD);
◆ GB/T 9364.4-2016 Miniature fuses—Part 4: Universal modular fuse-links (UMF)—Through-hole and surface mount types (IEC 60127-4: 2012, MOD);
◆ GB/T 9364.5-2011 Miniature fuses—Part 5: Guidelines for quality assessment of miniature fuse-links (IEC 60127-5: 1988, IDT);
◆ GB/T 9364.6-2001 Miniature fuses—Part 6: Fuse-holders for miniature cartridge fuse-links (IEC 60127-6: 1994, IDT);
◆ GB/T 9364.7-2016 Miniature fuses—Part 7: Miniature fuse-links for special applications (IEC 60127-7: 2013, MOD);
◆ GB/T 9364.10-2013 Miniature fuses—Part 10: User guide for miniature fuses (IEC 60127-10: 2001, MOD).
——Item e) in Clause 10 “Marking” is deleted since this requirement has already been included in GB/T 3836.1-2021.
The following editorial changes have been made to this document:
——In order to be consistent with the current standard series, the name of this document is modified to Explosive atmospheres—Part 9: Equipment protection by encapsulation “m”;
——Footnotes in Table 1 are combined with notes;
——The revised contents of IEC 60079-18: 2014/AMD1: 2017 and technology content of IEC 60079-18: 2014/COR1: 2018 are included, and are marked with perpendicular double lines (||) in the outside page margin of the provisions concerned;
——The "Bibliography" is modified (see Bibliography).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This document was proposed by China Electrical Equipment Industry Association.
This document is under the jurisdiction of SAC/TC 9 National Technical Committee on Explosion Protected Electrical Apparatus of Standardization Administration of China.
The previous editions of this document are as follows:
——GB 3836.9, which was issued in 1990 for the first time, first revised in 2006 and second revised in 2014;
——GB 12476.6, which was issued for the first time in 2010.
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Introduction
GB/T 3835 Explosive atmospheres is prepared in order to establish the basic technical requirements for equipment used in explosive atmospheres and its application, covering the design, manufacture, inspection, selection, installation, inspection, maintenance, repair and site classification of equipment used in explosive atmospheres, and adopts the form of partial standards, including but not limited to the following parts:
——Part 1: Equipment—General requirements;
——Part 2: Equipment protection by flameproof enclosures “d”;
——Part 3: Equipment protection by increased safety “e”;
——Part 4: Equipment protection by intrinsic safety "i";
——Part 5: Equipment protection by pressurized enclosure “p”;
——Part 6: Equipment protection by oil immersion “o”;
——Part 7: Equipment protection by powder filling “q”;
——Part 8: Equipment protection by type of protection “n”;
——Part 9: Equipment protection by type of protection “m”;
——Part 11: Material characteristics for gas and vapour classification—Test methods and data;
——Part 12: Material characteristics for combustible dusts—Test methods;
——Part 13: Equipment repair, overhaul and reclamation;
——Part 14: Classification of areas - Explosive gas atmosphere;
——Part 15: Electrical installations design, selection and erection;
——Part 16: Electrical installations inspection and maintenance;
——Part 17: Equipment protection by pressurized room “p” and artificially ventilated room “v”;
——Part 18: Intrinsically safe electrical systems;
——Part 20: Equipment with equipment protection level (EPL) Ga;
——Part 21: Application of quality systems for equipment manufacture;
——Part 22: Protection of equipment and transmission system using optical radiation;
——Part 23: Group I, category EPL Ma equipment intended to remain functional in atmospheres endangered by firedamp and/or coal dust;
——Part 24: Equipment protection by special protection “s”;
——Part 25: Requirements for process sealing between flammable process fluids and electrical systems;
——Part 26: Electrostatic hazards—Guidance;
——Part 27: Electrostatic hazards—Test;
——Part 28: Non-electrical equipment for potentially explosive atmospheres—Basic method and requirements;
——Part 29: Non-electrical equipment for explosive atmospheres—Constructional safety “c”, control of ignition source “b”, liquid immersion “k”;
——Part 30: Equipment and components in explosive atmospheres in underground mines;
——Part 31: Equipment dust ignition protection by enclosure “t”;
——Part 32: Intrinsically safe systems with electronically controlled spark duration limitation;
——Part 33: Equipment in adverse service conditions;
——Part 34: Equipment assemblies;
——Part 35: Classification of areas for explosive dust atmospheres;
Encapsulation "m" is an important explosion protection type. In terms of standardization of this technology, China formulated GB 3836.9-1990 on encapsulation type for explosive gas atmospheres with reference to IEC documents in 1990, and then revised it twice with IEC 60079-18 in 2006 and 2014; in 2010, IEC 61241-18 was adopted to formulate GB 12476.6-2010 on encapsulation type for combustible dust atmospheres. Since the release and implementation of the above standards, there has been a certain new development in encapsulated explosion protection technology. In terms of international standards, the current edition of the corresponding standard is IEC 60079-18: 2014, and its main technical contents may also be applied to China. GB 3836.9 needs to be revised and GB 12476.6 needs to be integrated in order to adapt to the development of explosion protection technology and industry and conform to the development of international standards.
On the basis of adopting the main technical contents of IEC 60079-18: 2014, Explosive atmospheres—Part 18: Equipment protection by encapsulation “m”, this revision has made appropriate modifications to adapt to the specific conditions of China. This document is a supplement and modification to the general requirements of GB/T 3836.1 as a part of specific explosion protection type.
Explosive atmospheres—Part 9: Equipment protection by encapsulation “m”
1 Scope
This document gives the specific requirements for the construction, testing and marking of electrical equipment, parts of electrical equipment and Ex components with the type of protection encapsulation “m” intended for use in explosive gas atmospheres or explosive dust atmospheres.
This document is applicable to encapsulated electrical equipment, encapsulated parts of electrical equipment and encapsulated Ex components (hereinafter always referred to as “m” equipment) where the rated voltage does not exceed 11 kV.
The application of electrical equipment in atmospheres, which may contain explosive gas as well as combustible dust simultaneously, may require additional protective measures.
This document is not applicable to dusts of explosives, which do not require atmospheric oxygen for combustion, or to pyrophoric substances.
This document does not take account of any risk due to an emission of flammable or toxic gas from the dust.
This document supplements and modifies the general requirements of GB/T 3836.1. Where a requirement of this document conflicts with a requirement of GB/T 3836.1, the requirement of this document will take precedence.
2 Normative references
The following documents contain provisions 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 1408.1 Electrical strength of insulating materials—Test methods—Part 1: Tests at power frequencies (GB/T 1408.1-2016, IEC 60243-1: 2013, IDT)
GB/T 3836.1 Explosive atmospheres—Part 1: Equipment—General requirements (GB/T 3836.1-2021, IEC 60079-0: 2017, MOD)
GB/T 3836.3 Explosive atmospheres—Part 3: Equipment protection by increased safety “e” (GB/T 3836.3-2021, IEC 60079-7: 2015, MOD)
GB/T 3836.4 Explosive atmospheres—Part 4: Equipment protection by intrinsic safety “i” (GB/T 3836.4-2021, IEC 60079-11: 2011, MOD)
GB/T 3836.8 Explosive atmospheres—Part 8: Equipment protection by type of protection “n” (GB/T 3836.8-2021, IEC 60079-15: 2017, MOD)
GB/T 3836.20 Explosive atmospheres—Part 20: Equipment with equipment protection level (EPL) Ga (GB/T 3836.20-2010, IEC 60079-26: 2006, MOD)
GB/T 3836.31 Explosive atmospheres—Part 31: Equipment dust ignition protection by enclosure “t” (GB/T 3836.31-2021, IEC 60079-31: 2013, MOD)
GB/T 7153 Directly heated positive step-function temperature coefficient thermistors—Part 1: Generic specification (GB/T 7153-2002, IEC 60738-1: 1998, IDT)
GB/T 9364 (all parts) Miniature fuses [IEC 60127 (all parts)]
GB/T 9816.1 Thermal-links—Part 1: Requirements and application guide (GB/T 9816.1-2013, IEC 60691: 2002, MOD)
GB/T 14536.10 Automatic electrical controls for household and similar use—Particular requirements for temperature sensing controls (GB/T 14536.10-2008, IEC 60730-2-9-2004, IDT)
GB/T 17045 Protection against electric shock—Common aspects for installations and equipment (GB/T 17045-2020, IEC 61140: 2016, IDT)
GB/T 19212.1 Safety of transformers, reactors, power supply units and combinations thereof—Part 1: General requirements and tests (GB/T 19212.1-2016, IEC 61558-1: 2009, MOD)
GB/T 19212.7 Safety of transformers, reactors, power supply units and similar products for supply voltages up to 1 100 V—Part 7: Particular requirements and test for safety isolating transformers and power supply units incorporating safety isolating transformers (GB/T 19212.7-2012, IEC 61558-2-6: 2009, IDT)
IEC 62326-4-1 Printed boards—Part 4: Rigid multilayer printed boards with interlayer connections-Sectional specification—Section 1: Capability detail specification—Performance levels A, B and C
ANSI/UL 248 (all parts) Standard for low-voltage fuses
ANSI/UL 7468 Standard for polymeric materials—Long term property evaluations
ANSI/UL 796 Printed-Wiring Boards
IPC-A-600 Acceptability of Printed Boards
IPC-6012 Qualification and Performance Specification for Rigid Printed Boards
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 3836.1 and the following apply.
Note: Additional terms and definitions applicable to explosive atmospheres can be found in GB/T 2900.35.
3.1
encapsulation “m”
type of explosion protection whereby parts that are capable of igniting an explosive atmosphere by either sparking or heating are fully enclosed in a compound or other non-metallic enclosure with adhesion in such a way as to avoid ignition of a dust layer or explosive atmosphere under operating or installation conditions
3.2
temperature range of the compound
range of temperatures within which the properties of the compound, in either operation or storage, permit compliance with the requirements of this document
3.3
free surface
compound surface exposed to the explosive atmospheres and/or dust layers
3.4
switching contact
mechanical contact, which makes and breaks an electrical circuit
3.5
adhesion
moisture, gas and dust tight permanent bonding of a compound to a surface
3.6
countable fault
fault which occurs in parts of electrical equipment conforming to the constructional requirements
3.7
infallible separation
separation between electrically conductive parts that is considered as not subject to short-circuits
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3.8
solid insulation
insulation material which is extruded or molded, but not poured
Note: Insulators fabricated from two or more pieces of electrical insulating material, which are infallibly bonded together may be considered as solid.
4 General
4.1 Level of protection [equipment protection level (EPL)]
Electrical equipment with encapsulation “m” shall be either:
a) level of protection “ma” (EPL “Ma, Ga, Da”); or
b) level of protection “mb” (EPL “Mb, Gb, Db”); or
c) level of protection “mc” (EPL “Gc, Dc”).
The requirements of this document apply to all levels of protection for encapsulation “m” unless otherwise stated.
4.2 Additional requirements for levels of protection “ma” and “mb”
Components without additional protection shall be used only if they cannot damage the encapsulation mechanically or thermally in the case of any fault conditions specified in this document.
Alternatively, where a fault of an internal component may lead to failure of encapsulation “m” due to increasing temperature, the requirements of 7.9 shall apply.
4.3 Additional requirements for level of protection “ma”
The working voltage at any point in the circuit shall not exceed 1 kV.
4.4 Rated voltage and prospective short-circuit current
The rated voltage and the prospective short-circuit current shall be specified such that the limiting temperature is not exceeded for the relevant level of protection “ma”, “mb” or “mc”.
Foreword i
Introduction vii
1 Scope
2 Normative references
3 Terms and definitions
4 General
5 Requirements for compounds
6 Temperatures
7 Constructional requirements
8 Type test
9 Routine verifications and tests
10 Marking
Annex A (Information) Basic requirements for compounds for “m” equipment
Annex B (Informative) Allocation of test samples
Annex C (Normative) Dielectric strength test between circuit and environment
Bibliography
