GB/T 3836.9-2021_English: PDF (GB/T3836.9-2021)
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Standard ID | GB/T 3836.9-2021 (GB/T3836.9-2021) | Description (Translated English) | Explosive atmospheres -- Part 9: Equipment protection by encapsulation ''m'' | Sector / Industry | National Standard (Recommended) | Classification of Chinese Standard | K35 | Classification of International Standard | 29.260.20 | Word Count Estimation | 32,384 | Date of Issue | 2021-10-11 | Date of Implementation | 2022-05-01 | Older Standard (superseded by this standard) | GB 12476.6-2010; GB 3836.9-2014 | Drafting Organization | Nanyang Explosion-proof Electrical Research Institute Co., Ltd., Shenyang Research Institute Co., Ltd. of Coal Science and Technology Group, Shanghai Inspection and Testing Institute of Instrumentation and Automatic Control System Co., Ltd., China Coal Science and Industry Group Chongqing Research Institute Co., Ltd., Wolong Electric Nanyang Explosion-proof Group Co., Ltd., New Liming Technology Co., Ltd., Huarong Technology Co., Ltd., Feice Explosion-proof Electric Co., Ltd., Chuangzheng Electric Co., Ltd., Nanyang Zhongtian Explosion-proof Electric Co., Ltd. | Administrative Organization | National Standardization Technical Committee for Explosion-proof Electrical Equipment (SAC/TC 9) | Regulation (derived from) | National Standard Announcement No. 12 of 2021 | Proposing organization | China Electrical Equipment Industry Association | Issuing agency(ies) | State Administration for Market Regulation, National Standardization Administration | Standard ID | GB 3836.9-2014 (GB3836.9-2014) | Description (Translated English) | Electrical apparatus for explosive gas atmospheres Part 9: Encapsulation m | Sector / Industry | National Standard | Classification of Chinese Standard | K35 | Classification of International Standard | 29.260.20 | Word Count Estimation | 26,220 | Date of Issue | 2014/12/5 | Date of Implementation | 2015/10/16 | Older Standard (superseded by this standard) | GB 3836.9-2006 | Quoted Standard | GB/T 1034-2008; GB/T 1408.1-2006; GB 3836.1-2010; GB 3836.3-2010; GB 3836.4-2010; GB 3836.8-2014; GB 3836.20-2010; GB/T 7153-2002; GB 9364.1; GB 9364.2; GB 9364.3; GB 9364.4; GB 9364.5; GB 9364.6; GB 9364.10; GB 9816.1-2013; GB 14536.10-2008; GB 12476.4-2 | Adopted Standard | IEC 60079-18-2009, MOD | Drafting Organization | Nanyang Institute of Electrical Explosion | Administrative Organization | National Standardization Technical Committee explosion-proof electrical equipment | Regulation (derived from) | Announcement of Newly Approved National Standards 2014 No. 27 | Proposing organization | China Electrical Equipment Industry Association | Issuing agency(ies) | General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China | Summary | This Standard specifies the explosive gas atmospheres and explosive dust atmospheres made Encapsulation "m" construction, testing and marking of electrical protection equipment, electrical equipment components and requirements for Ex element. This section | Standard ID | GB 3836.9-2006 (GB3836.9-2006) | Description (Translated English) | Electrical apparatus for explosive gas atmospheres Part 9: Encapsulation m | Sector / Industry | National Standard | Classification of Chinese Standard | K35 | Classification of International Standard | 29.260.20 | Word Count Estimation | 22,232 | Date of Issue | 2006-12-01 | Date of Implementation | 2007-06-01 | Older Standard (superseded by this standard) | GB 3836.9-1990 | Adopted Standard | IEC 60079-18-2004, IDT | Drafting Organization | Explosion Protection Electric Institute | Administrative Organization | National Standardization Technical Committee explosion-proof electrical equipment | Regulation (derived from) | Announcement of Newly Approved National Standards No. 13 of 2006 (No. 100 overall) | Proposing organization | China Electrical Appliances Industry Association | Issuing agency(ies) | General Administration of Quality Supervision, Inspection and Quarantine of PRC, China National Standardization Administration Committee | Summary | This Chinese standard provides Encapsulation"m"electrical equipment, electrical equipment parts and Ex components in the construction and testing of specific requirements. This standard only applies to the rated voltage not exceeding 10 kV, 10% relative tolerance Encapsulated electrical equipment, electrical equipment components encapsulated and encapsulated Ex components (hereinafter also called"m"device). This standard is the GB 3836. 1 General requirements supplement. |
GB/T 3836.9-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.260.20
CCS K 35
Replacing GB 3836.9-2014, GB 12476.6-2010
Explosive Atmospheres - Part 9: Equipment Protection
by Encapsulation “m”
(IEC 60079-18:2014, Explosive Atmospheres - Part 18: Equipment
Protection by Encapsulation “m”, MOD)
ISSUED ON: OCTOBER 11, 2021
IMPLEMENTED ON: MAY 1, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3
Introduction ... 9
1 Scope ... 12
2 Normative References ... 12
3 Terms and Definitions ... 14
4 General ... 15
5 Requirements for Compounds ... 15
6 Temperatures ... 17
7 Constructional Requirements ... 18
8 Type Tests ... 35
9 Routine Verifications and Tests ... 41
10 Marking ... 42
Appendix A (informative) Basic Requirements for Compounds for “m”
Equipment ... 43
Appendix B (informative) Allocation of Test Samples ... 45
Appendix C (normative) Dielectric Strength Test between Circuits and
Environment ... 46
Bibliography ... 48
Foreword
This document was drafted in accordance with the rules in GB/T 1.1-2020 Directives
for Standardization - Part 1: Rules for the Structure and Drafting of Standardizing
Documents.
This document is Part 9 of GB/T 3836 Explosive Atmospheres. GB/T 3836 has
released 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 Liquid Immersion “o”;
---Part 7: Equipment Protection by Powder Filling “q”;
---Part 8: Equipment Protection by Type of Protection “n”;
---Part 9: Equipment Protection by Encapsulation “m”;
---Part 11: Material Characteristics for Gas and Vapor Classification - Test Methods
and Data;
---Part 12: Material Characteristics for Combustible Dusts - Test Methods;
---Part 13: Equipment Repair, Overhaul, Reclamation and Modification;
---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 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 serves as a replacement of 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 focuses on GB 3836.9-2014 and integrates the
main content of GB 12476.6-2010. In comparison with GB 3836.9-2014, apart from
structural adjustments and editorial modifications, the main technical changes are as
follows:
---Additional requirements for protection level “mb” are added (see 4.2);
---The requirements for thermal conductivity are added to the specification (see
5.2);
---The option of determining reliable components and isolation compounds in a
fault is added (see 7.2);
---The dimensional drawing of compound thickness is modified (see 7.4.1; 7.4.1
of Version 2014);
---Standard options for multi-layer printed circuit boards with rigid through-
connections are added (see 7.4.3.1);
---Additional requirements for batteries are modified and added (see 7.8.3; 7.8.3
of Version 2014);
---The requirements for 2 protective devices with protection level “ma” are added
(see 7.9.2);
---The requirements for 2 thermal protective devices with protection level “mb” are
added (see 7.9.3);
---The restriction of two-thirds of the rated voltage of the resettable thermal
protective device with switching contacts is deleted (see 7.9.3 of Version 2014);
---The requirements for the determination of the maximum surface temperature of
protection level “Da” are added (see 8.2.2);
---The reference service temperature of the thermal endurance test is modified
(see 8.2.3.1; 8.2.3.1 of Version 2014);
---The option of type test of dielectric strength is added (see 8.2.4.1);
---An alternative method for the pressure test of equipment with protection level
“mb” is added (see 8.2.6);
---The requirement for the number of samples for sealing test with built-in
protective devices and the method of reducing samples are added (see 8.2.8);
---Different situations of routine dielectric strength test are added (see 9.2);
---The requirements for the dielectric strength test between the circuit and the
environment are added (see Appendix C).
This document adopts the re-drafting method in the modification and adoption of IEC
60079-18:2014 Explosive Atmospheres - Part 18: Equipment Protection by
Encapsulation “m”.
The technical differences between this document and IEC 60079-18:2014, and the
causes for the differences are as follows:
---In terms of Normative References, this document makes certain adjustments
with technical differences, so as to adapt to the technical conditions of China.
The adjustments are intensively reflected in Chapter 2 “Normative References”.
See the specific adjustments below:
GB/T 1408.1, which equivalently adopts international standard, is used to
replace IEC 60243-1 (see 5.2);
GB/T 3836.1, which modifies and adopts international standard, is used to
replace IEC 60079-0 (see Chapter 1);
GB/T 3836.3, which modifies and adopts international standard, is used to
replace IEC 60079-7 (see 7.2.2);
GB/T 3836.4, which modifies and adopts international standard, is used to
replace IEC 60079-11 (see 7.2.2);
GB/T 3836.8, which modifies and adopts international standard, is used to
replace IEC 60079-15 (see 7.5.2);
GB 3836.20, which modifies and adopts international standard, is used to
replace IEC 60079-26 (see 7.6.2);
GB/T 3836.31, which modifies and adopts international standard, is used
to replace IEC 60079-31 (see 7.6.2);
GB/T 7153, which equivalently adopts international standard, is used to
replace IEC 60738-1 (see 7.9.3);
GB/T 9816.1, which modifies and adopts international standard, is used to
replace IEC 60691 (see 7.8.5);
GB/T 14536.10, which equivalently adopts international standard, is used
to replace IEC 60730-2-9 (see 7.9.3);
GB/T 17045, which equivalently adopts international standard, is used to
replace IEC 61140 (see 7.2.3);
GB/T 19212.1, which modifies and adopts international standard, is used
to replace IEC 61558-1 (see 7.2.3);
GB/T 19212.7, which equivalently adopts international standard, is used to
replace IEC 61558-2-6 (see 7.2.3);
GB/T 9364 (all parts) is used to replace IEC 60127 (all parts) (see 7.8.5).
The degree of consistency between the 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 Small Fuses - Part 4: Universal Module Fuse-links
(UMF) - Perforated and Surface Mount (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 Small Fuses - Part 7: Small-sized 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).
---e) is deleted from Chapter 10 Marking, because this requirement is already
included in GB/T 3836.1-2021.
This document makes the following editorial modifications:
---In order to be consistent with the existing standard series, the title of this
document is modified into Explosive Atmospheres - Part 9: Equipment
Protection by Encapsulation "m";
---The FOOTNOTE and NOTE in Table 1 are incorporated;
---The Amendment of IEC 60079-18:2014/AMD1:2017 and the Corrigendum of
IEC 60079-18:2014/COR1:2018 are incorporated; the outer margin of the
involved clauses is marked with a vertical double line ( );
---The Bibliography is modified.
Please be noted that certain content of this document may involve patents. The
institution issuing this document does not undertake the responsibility of identifying
these patents.
This document was proposed by China Electrical Equipment Industry Association.
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 applies only for 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 does not apply 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 standard conflicts with a requirement of GB/T 3836.1, the
requirement of this document takes precedence.
2 Normative References
The contents of the following documents constitute indispensable clauses of this
document through normative references in the text. In terms of references with a
specified date, only versions with a specified date are applicable to this document. In
terms of references without a specified date, the latest version (including all the
modifications) is applicable to this document.
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 3836.20 Explosive Atmospheres - Part 20: Equipment with Equipment Protection
Level (EPL) Ga (GB 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 Miniature Fuses (all parts) [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 Power Transformers, Power Supplies, Reactors and Similar
Products - 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 746B Standard for Polymetric Materials - Long Term Property Evaluations
ANSI/UL 796 Printed-wiring Boards
......
GB 3836.9-2014
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.260.20
K 35
Replacing GB3836.9-2006
Explosive atmospheres - Part 9: Equipment protection
by type of protection “m”
(IEC 60079-18:2009, Explosive atmospheres - Part 18: Equipment
protection by type of protection “m”, MOD)
ISSUED ON: DECEMBER 5, 2014
IMPLEMENTED ON: OCTOBER 16, 2015
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 4
1 Scope ... 7
2 Normative references ... 7
3 Terms and definitions ... 9
4 General ... 11
4.1 Level of protection [Equipment protection level (EPL)] ... 11
4.2 Additional requirements for level of protection “ma” ... 11
4.3 Rated voltage and prospective short circuit current ... 12
5 General requirements ... 12
5.1 General ... 12
5.2 Specification ... 12
5.3 Properties of the compound ... 13
6 Temperatures... 13
6.1 General ... 13
6.2 Determination of the limiting temperature ... 13
6.3 Temperature limitation ... 14
7 Constructional requirements ... 14
7.1 General ... 14
7.2 Determination of faults ... 15
7.3 Free space in the encapsulation ... 17
7.4 Thickness of the compound ... 20
7.5 Switching contacts ... 22
7.6 External connections ... 23
7.7 Protection of bare live parts ... 24
7.8 Cells and batteries ... 24
7.9 Protective devices ... 27
8 Type tests ... 30
8.1 Tests on the compound ... 30
8.2 Tests on the apparatus ... 30
9 Routine verifications and tests ... 35
9.1 Visual inspections ... 35
9.2 Dielectric strength test ... 35
10 Marking ... 35
Annex A (Informative) Basic requirements for compounds for “m” equipment
... 37
Annex B (Normative) Allocation of test samples ... 38
Foreword
All the technical content of this Part is compulsory.
GB 3836, Explosive atmospheres, comprises 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 liquid 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: Method of test for ascertainment of maximum experimental safe
gap;
-- Part 12: Classification of gases or vapours with air according to their
maximum experimental safe gaps and minimum igniting current;
-- 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: Construction and use of rooms or buildings protected by
pressurization;
-- Part 18: Intrinsically safe electrical systems;
-- Part 19: Fieldbus intrinsically safe concept (FISCO);
-- Part 20: Equipment with equipment protection level (EPL) Ga.
This Part is Part 9 of GB 3836.
This Part was drafted in accordance with the rules given in GB/T 1.1-2009.
This Part replaces GB 3836.9-2006, Electrical apparatus for explosive gas
atmospheres - Part 9: Encapsulation “m”. The significant technical changes with
respect to GB 3836.9-2006 are as follows:
-- it adds the level of protection “mc”;
-- it adds the levels of equipment protection (including EPL Ma, Ga, Da, Mb, Gb, Db,
Gc, Dc);
-- it adds the requirements for dust;
-- it adds switching contacts of level “ma”.
This Part was redrafted by modifying and adopting IEC 60079-18:2009, Explosive
atmospheres - Part 18: Equipment protection by encapsulation “m”.
The technical differences between this Part and IEC 60079-18:2009, and the reasons,
are as follows:
-- in the normative references, the undated references are changed into dated
references;
-- in the normative references, IEC 30127 (all parts) are changed into GB 9364 (all
parts).
The degree of consistency between GB 9364 (all parts) and IEC 60127 (all parts) is as
follows:
GB 9364.1-1997, Miniature fuses - Part 1: Definitions for miniature fuses and
general requirement for miniature fuse-links (idt IEC 60127-1:1988);
GB 9364.2-1997, Miniature fuses - Part 2: Cartridge fuse-links (idt IEC 30127-
2:1989);
GB 9364.3-1997, Miniature fuses - Part 3: Sub-miniature fuse-links (idt IEC
60127-3:1998);
GB 9364.4-2006, Miniature fuses - Part 4: Universal Modular Fuse-links (UMF)
(IEC 60127-4:1996, IDT);
GB 9364.5-2011, Miniature fuses - Part 5: Guidelines for quality assessment of
miniature fuse-links (IEC 60127-5:1998, IDT);
GB 9364.6-2001, Miniature fuses - Part 6: Fuse-holders for miniature cartridge
fuse-links (IEC 60127-6:1994, IDT).
This Part was proposed by the China Electrical Equipment Industrial Association.
This Part shall be under the jurisdiction of National Technical Committee 9 on Electrical
Apparatus for Explosive Atmospheres of Standardization Administration of China
(SAC/TC 9).
The drafting organizations of this Part: Nanyang Explosion Protected Electrical
Apparatus Research Institute, China National Quality Supervision and Test Center for
Explosion Protected Electrical Products, Warom Technology Incorporated Company,
Shenzhen Orena Photon Technology Co., Ltd., Helon Explosion-Proof Electric Co.,
Ltd., Dianguang Explosion Protection Electric Co., Ltd.
The main drafters of this Part: Mu Dayu, Zhang Gang, Zhou Jing, Qiu Wenbo, Xie
Shaojian, Shi Xiaoxian, Liu Hengyun, Zhang Xiaoli.
The previous editions of the standard replaced by this Part are as follows:
-- GB 3836.9-1990, GB 3836.9-2006.
Explosive atmospheres - Part 9: Equipment protection
by type of protection “m”
1 Scope
This part of GB 3836 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 part applies only for 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 standard does not apply to dusts of explosives, which do not require atmospheric
oxygen for combustion, or to pyrophoric substances.
This standard does not take account of any risk due to an emission of flammable or
toxic gas from the dust.
This standard supplements and modifies the general requirements of GB 3836.1-2010.
Where a requirement of this standard conflicts with a requirement of GB 3836.1-2010,
the requirement of this standard shall take precedence.
2 Normative references
The following referenced documents are indispensable for the application of this
document. For dated references, only the edition dated applies to this document. For
undated references, the latest edition of the referenced documents (including all
amendments) applies to this document.
GB/T 1034-2008, Plastics – Determination of water absorption (ISO 62:2008)
GB/T 1408.1-2006, Electrical strength of insulating materials – Test methods –
Part 1: Tests at power frequencies (IEC 60243-1:1998, IDT)
GB 3836.1-2010, Explosive atmospheres – Part 1: Equipment – General
requirements (IEC 60079-0: MOD)
GB 3836.3-2010, Explosive atmospheres – Part 3: Equipment protection by
increased safety e (IEC 60079-7:2006, IDT)
GB 3836.4-2010, Explosive atmospheres – Part 4: Equipment protection by
intrinsic safety I (IEC 60079-11:2006, MOD)
GB 3836.8-2014, Explosive atmospheres – Part 8: Equipment protection by type
of protection “n” (IEC 60079-15:2010, MOD)
GB 3836.20-2010, Explosive atmospheres – Part 20: Equipment with equipment
protection level (EPL) Ga (IEC 60079-26:2006, IDT)
GB/T 7153-2002, Directly heated positive step-function temperature coefficient
thermistors – Part 1:Generic specification (idt IEC 60738-1:1998)
GB 9364 (all parts), Miniature fuses [IEC 60127 (all parts)]
GB 9816.1-2013, Thermal-links – Part 1: Requirements and application guide (IEC
60691:2002 + A1:2006, IDT)
GB 14536.10-2008, Automatic electrical controls for household and similar use –
Particular requirements for temperature sensing controls (IEC 60730-2-9:2004,
IDT)
GB 12476.4-2010, Electrical apparatus for use in the presence of combustible dust
– Part 4: Protection by intrinsic safety “iD” (IEC 61241-11:2005, IDT)
GB/T 16855.1-2008, Safety of machinery – Safety-related parts of control systems
– Part 1: General principles for design (ISO 13849-1:2006, IDT)
GB/T 16935.1-2008, Insulation coordination for equipment within low-voltage
systems – Part 1: Principles requirements and tests (IEC 60664-1:2007, IDT)
GB 19212.7-2012, 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
IEC 60079-31:2008, Explosive atmospheres – Part 31: Equipment dust ignition
protection by enclosure “t”
IEC 62326-4-1:1996, 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 248-1, Standard for low-voltage fuses – Part 1: General requirements
ANSI/UL 746B-2009, Standard for polymetric materials – Long term property
evaluations
3 Terms and definitions
For the purposes of this document, the following terms and definitions, and those given
in GB 3836.1-2010, apply.
3.1
encapsulation “m”
type of protection whereby parts that are capable of igniting an explosive atmosphere
by either sparking or heating are enclosed in a compound in such a way as to avoid
ignition of a dust layer or explosive atmosphere under operating or installation
conditions
3.2
compounds
any thermosetting, thermoplastic, epoxy resin or elastomeric materials with or without
fillers and/or additives, in their solid state
3.3
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 standard
3.4
continuous operating temperature (COT) of the compound
temperature range within which, according to the details given by the manufacturer,
the properties of the compound, during operation, satisfy the requirements of this
standard on a permanent basis during the foreseen lifetime of the equipment
encapsulation process of applying the compound to enclose any electrical device(s)
by suitable means
3.5
encapsulation
process of applying the compound to enclose any electrical device(s) by suitable
means
3.6
free surface
compound surface exposed to the explosive atmospheres and/or dust layers
3.7
normal operation
operation of equipment conforming electrically and mechanically with its design
specification and used within the limits specified by the manufacturer
NOTE 1: The limits specified by the manufacturer may include persistent operational conditions,
for example operation of a motor on a duty cycle.
NOTE 2: Variation of the supply specifications within stated limits and any other operational
tolerance is part of normal operation.
3.8
void
unintentional space created as a consequence of the encapsulation process
3.9
free space
intentionally created space surrounding components or space inside components
3.10
switching contact
mechanical contact, which makes and breaks an electrical circuit
3.11
adhesion
moisture, gas and dust tight permanent bonding of a compound to a surface
3.12
countable fault
fault, which occurs in parts of electrical equipment conforming to the constructional
requirements
3.13
infallible separation or insulation
separation or insulation between electrically conductive parts that is considered as not
subject to short circuits as specified in this Part. The probability of such fault modes
occurring in service or storage is considered to be so low that they are not to be
considered
3.14
non-countable fault
fault, which occurs in parts of electrical equipment not conforming to the constructional
requirements of this Part
3.15
solid insulation
insulation material, which is extruded or moulded, but not poured
NOTE: Insulators fabricated from two or more pieces of electrical insulating material, which are
solidly bonded together may be considered as solid. Varnish and similar coatings are not
considered to be solid insulation.
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”),
b) level of protection “mb” (EPL “Mb, Gb, Db”) or in
c) level of protection “mc” (EPL “Gc, Dc”).
The requirements of this standard shall apply to all levels of protection “m” (EPL`s)
unless otherwise stated.
4.2 Additional requirements for level of protection “ma”
The working voltage at any point in the circuit shall not exceed 1 kV.
Components without additional protection shall be used only if they cannot damage
the encapsulation mechanically or thermally in the case of any specified fault.
Alternatively, where a fault of an internal component may lead to failure of the
encapsulation “m” due to increasing temperature, the requirements of 7.9 shall apply.
4.3 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”.
5 General requirements
5.1 General
The documentation shall specify the compound(s) used and the processing method(s).
As a minimum, those properties of the compound(s) on which the encapsulation “m”
depends shall be provided.
Due consideration should be given in the selection of compounds to allow for the
expansion of components during operation and in the event of allowable faults.
For basic requirements of compounds, refer to Annex A.
5.2 Specification
The specification for the compound shall include the following:
a) the name and address of the manufacturer of the compound,
b) the exact and complete reference of the compound and if relevant, percentage
of fillers and any other additives, the mixture ratios and the type designation,
c) if applicable, any treatment of the surface of the compound(s), for example
varnishing,
d) if applicable, to obtain correct adhesion of the compound to a component, any
requirement for pre-treating of the component for example cleaning, etching,
e) the dielectric strength in accordance with GB/T 1408.1-2006 at the maximum
temperature of the equipment determined according to 8.2.2 if available. If not
available, the requirements of 5.3.2 shall be applied,
f) temperature range of the compound(s) (continuous operating temperature),
g) in the case of “m” equipment where the compound is part of the external
enclosure, the temperature index TI value as defined by GB 3836.1-2010. As an
alternative to the TI, the relative thermal index (RTI-mechanical impact) may be
determined in accordance with ANSI/UL 746B-2009,
h) the colour of the compound used for the test samples, where the compound
specification will be influenced by changing the colour.
NOTE: It is not a requirement of this standard that conformity to the manufacturer’s specification
of the compound needs to be verified.
5.3 Properties of the compound
5.3.1 Water absorption
If the equipment is to be exposed to dampness, the compound shall be tested in
accordance with 8.1.1. If this test is not performed, the equipment shall be marked “X”
in accordance with the marking requirements of GB 3836.1 and the restriction of use
to dry environments clarified in the instructions.
5.3.2 Dielectric strength
Where the dielectric strength according to GB/T 1408.1-2006 is not available at the
maximum temperature of the equipment as defined according to 8.2.2, see 5.2 e), a
test shall be performed in accordance with 8.1.2.
6 Temperatures
6.1 General
The maximum value of the continuous operating temperature of the compound shall
not be exceeded under normal operation. The maximum surface temperature,
determined in accordance with GB 3836.1-2010, shall not be exceeded under normal
operation and under fault conditions as defined in 7.2.1. The “m” equipment shall be
protected in such a way that the encapsulation “m” is not adversely affected under
these fault conditions.
NOTE: Normal operation includes operation at the extremes of voltage tolerances of the supply
normally 90 % to 110 % if not otherwise specified.
6.2 Determination of the limiting temperature
6.2.1 Maximum surface temperature
The maximum surface temperature shall be determined using the test method given
in 8.2.2 in accordance with the supply conditions specified in 4.3. This temperature
shall be used to determine the temperature class for explosive gas atmosphere or the
maximum surface temperature in degrees Celsius for explosive dust atmosphere of
the equipment.
6.2.2 Temperature of the compound
The hottest component(s) shall be determined. The maximum temperature in the
compound, adjacent to the hottest component(s), shall be determined using the test
method given in 8.2.2 for normal operation.
As an alternative the determination of the temperature of the hottest component may
be done by calculation, manufacturer’s specification or by a practical test prior to
encapsulating the components.
6.3 Temperature limitation
Where the equipment may be subject to fault in accordance with 7.2.1, or where there
is the possibility of an increased temperature, for example by an unfavourable input
voltage in accordance with 7.2.1 or an unfavourable load, this shall be considered in
determining the limiting temperatures.
When a protective device is required to limit temperatures for safety reasons, it shall
be an internal or external, electrical or thermal device, as defined in 7.9.
7 Constructional requirements
7.1 General
Where the compound forms part of the external enclosure it shall comply with the
requirements of GB 3836.1-2010 for non-metallic enclosures and parts of non-metallic
enclosures.
If the surface of the compound is totally or partly surrounded by an enclosure and the
enclosure is part of the protection, the enclosure or parts of the enclosure shall comply
with the enclosure requirements of GB 3836.1-2010.
If additional protective measures are required to be provided by the user in order to
satisfy the requirements of this standard, for example, additional mechanical protection,
to indicate this specific condition of use the equipment shall be in accordance with the
“specific conditions of use” marking requirements of GB 3836.1-2010.
Appropriate action shall be taken to accommodate the expansion of components
during normal operation and in the event of faults according to 7.2.
In 7.2 to 7.9 the requirements differ according to whether the compound adheres to
the enclosure. Where adhesion is specified, the aim is to prevent the ingress of
explosive atmospheres and moisture at the boundary surfaces (for example enclosure-
compound, compound-parts that are not completely embedded in the compound, such
as printed wiring boards, connection terminals, etc.). Where adhesion is required to
maintain the type of protection, it shall be maintained after completion of all the
prescribed tests.
The choice of the compound(s) to be used for a specific application is dependent on
the task each compound has to perform. In general, testing a compound once is not
sufficient for universal use for encapsulation “m”.
7.2 Determination of faults
7.2.1 Fault examination
The encapsulation “m” shall not be invalidated even under the most adverse input
rating, but between 90 % and 110 % of the rating and most adverse output load and
up to two internal countable faults for level of protection “ma”, and up to one internal
countable fault for level of protection “mb.
No faults are considered for level of protection “mc”.
NOTE: Examples of faults are: a short circuit in any component; the failure of any component
and a fault in the printed wiring board.
Components meeting the requirements of 7.2.2 are not considered to fail and infallible
separation distances shall only be considered to fail in accordance with 7.2.4. The
failure of some components may result in an unstable condition, for example,
alternating between high and low resistance. In those cases, the most onerous
condition shall be considered.
If a fault leads to one or more subsequent faults, for example, due to the overload of a
component, the primary and subsequent fault(s) shall be considered to be a single
fault.
7.2.2 Components considered as not subject to fail
For levels of protection “ma” and “mb” the following components shall be considered
as not to fail if they are encapsulated according to the requirements of this standard, if
they are suitable for the service temperature and if they are not operated at more than
2/3 of their rated voltage, rated current or rated power specified by the manufacturer
of the respective component:
- resistors, if they comply with the current limiting resistors of GB 3836.4-2010,
- single-layer, spirally wound coils,
- plastic foil capacitors,
- paper capacitors,
- ceramic capacitors,
- shunt semiconductors, if they are used in accordance with the shunt safety
assemblies of GB 3836.4-2010,
- when series semiconductor devices used to limit current, a single device is
adequate for level of protection “mb”; two devices shall be used for level of
protection “ma”.
For levels of protection “ma” and “mb” coils, motor windings and transformers that
comply with GB 3836.3-2010, including also those that have wire diameters of less
than 0.25 mm shall be considered as not subject to failure if they are encapsulated
according to the requirements of this standard.
7.2.3 Isolating components
The following components for the segregation of different circuits shall be considered
to provide isolation and are not considered to fail across the segregation:
- optocouplers and relays, if the rated insulation voltage conforms to 2U + 1 000 V
r.m.s. 50 + % or 1 500 V r.m.s. whichever is greater (U is the sum of the rated
r.m.s. voltages of both circuits);
- transformers, complying with GB 19212.7-2012 or GB 3836.4-2010.
7.2.4 Infallible separation distances
7.2.4.1 General
It is not necessary to consider the possibility of a fault occurring as described in 7.2.1
in respect of voltage breakdown -- if applicable 7.2.4.3 and complying with the
requirements of 7.2.4.2 -- if the distances between bare current-carrying parts
- of the same circuit, or
- of a circuit and earthed metal parts, or
- of two separate circuits (sum of the working voltages shall be taken as the voltage
for Table 1; where one of the working voltages is less than 20 % of the other, it
shall be ignored).
7.2.4.2 Distances through the compound
Distances through compound shall be considered to be infallible against short circuit
for level of protection “ma” and level of protection “mb” if they comply with the values
in Table 1, provided that the distances in the compound are fixed or secured
mechanically before encapsulation.
Distances between the minimum distances given for level of protection “mc” and the
infallible distances given for level of protection “ma” and “mb” are not considered
infallible and shall be assessed as a “countable fault”. Distances less than those given
for level of protection “mc” are considered as short-circuits if this impairs the type of
protection “m”.
For level of protection “mc” the values of Table 1 are the constructional requirements
and may be achieved by mechanically fixing before encapsulation.
Table 1 -- Distances through the compound
7.2.4.3 Distances through solid insulation
The distance through solid insulation, on which the type of protection “m” depends,
shall be at least 0.1 mm and shall comply with the dielectric strength test of 8.2.4.
7.3 Free space in the encapsulation
7.3.1 Group III “m” equipment
The compound shall be free of voids.
The sum of the free spaces is not limited, but the volume of each individual free space
is limited to 100 000 mm3. The thickness of the compound surrounding such free
spaces shall meet the requirements of Table 2.
Voltage U r.m.s. or d.c.a
Minimum distance
mm
a Voltages shown are derived from GB/T 16935.1-2008. For all voltages, the actual voltage may exceed the value
given in the table by up to 10 %. This is based on the rationalisation of supply voltages given in Table F.3b of GB/T
16935.1-2008.
Table 2 -- Minimum thickness of compound adjacent to free space for Group III
“m” equipment
Level of
protection
Minimum thickness of
compound adjacent to free
space to:
Free space
≤ 1 cm3
1 cm3 < Free space
≤ 10 cm3
“ma”
Free space or free surface 3 mm 3 mm
Non-metallic or metal
enclosure with adhesion
3 mm (enclosure +
compound) a
3 mm (enclosure +
compound) a
Non-metallic or metal
enclosure without
adhesion
3 mm 3 mm
“mb”
Free space or free surface 1 mm 3 mm
Non-metallic or metal
enclosure with adhesion
1 mm (enclosure +
compound) a
3 mm (enclosure +
compound) a
Non-metallic or metal
enclosure without
adhesion
1 mm 3 mm
“mc”
Free space or free surface 1 mm 1 mm
Non-metallic or metal
enclosure with adhesion
1 mm (enclosure +
compound) a
1 mm (enclosure +
compound)
Non-metallic or metal
enclosure without
adhesion
1 mm 1 mm
NOTE: The thickness of the materials quoted in this table does not imply compliance with other
mechanical tests required by GB 3836.1-2010.
a Wall thickness of the enclosure ≥ 1 mm.
7.3.2 Group I and Group II “m” equipment
The compound shall be free of voids.
The sum of the free spaces shall not exceed
- 100 cm3 for level of protection “mb” and “mc”;
- 10 cm3 for level of protection “ma”.
The minimum thickness of the compound surrounding such free spaces shall comply
with Table 3.
Table 3 -- Minimum thickness of compound adjacent to free space for Group I
and Group II “m” equipment
Level of
protection
Minimum thickness of
compound adjacent to
free space to:
Free space
≤ 1 cm3
1 cm3 < Free space
≤ 10 cm3
1......
......
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