GB/T 3836.8-2021Explosive atmospheres - Part 8: Equipment protection by type of protection 'n' (English PDF)

Foreword

This document is drafted in accordance with GB/T 1.1-2020 "Directives for

standardization - Part 1.Rules for the structure and drafting of standardizing

documents".

This document is Part 8 of GB/T 3836 "Explosive atmospheres". GB/T 3836 has issued

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 vapour 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 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 replaces GB 3836.8-2014 "Electrical apparatus for explosive gas

atmospheres - Part 8.Type of protection 'n'". Compared with GB 3836.8-2014, the

main technical changes are as follows.

- Change the range of internal working voltage (see Clause 1; Clause 1 of the 2014

edition);

- Delete non-sparking device "nA", which has been included in GB/T 3836.3 "ec"

(see Clause 3 of the 2014 edition);

- Delete enclosed break device "nC", which has been included in GB/T 3836.2 "dc"

(see Clause 3 of the 2014 edition);

- Modify the definition of hermetically-sealed device "nC" (see Clause 3; Clause 3

of the 2014 edition);

- Add the definition of normally sparking device (see Clause 3);

- Delete the content of small components (see 5.2 of the 2014 edition);

- Delete the requirements for connectors and wiring cavities (see Clause 7 of the

2014 edition);

- Delete the supplementary requirements for non-sparking rotating electric machines

(see Clause 8 of the 2014 edition);

- Delete the supplementary requirements for non-sparking fuses and fuse assembly

(see Clause 9 of the 2014 edition);

- Delete the supplementary requirements for non-sparking plugs and sockets (see

Clause 10 of the 2014 edition);

- Delete the supplementary requirements for non-sparking luminaires (see Clause 11

of the 2014 edition);

- Delete the supplementary requirements for equipment with non-sparking cells (see

Clause 12 of the 2014 edition);

- Delete the supplementary requirements for non-sparking low-power equipment

(see Clause 13 of the 2014 edition);

- Delete the supplementary requirements for non-sparking current transformers (see

Clause 14 of the 2014 edition);

- - Delete the requirements for other non-sparking electrical equipment (see Clause

15 of the 2014 edition);

- Delete the general supplementary requirements for equipment generating arcs,

sparks or hot surfaces (see Clause 16 of the 2014 edition);

- Delete the requirements for enclosed circuit breakers (see Clause 17 of the 2014

edition);

- Add voltage and current limiting of non-incendive components (see 7.2);

- Change the requirements for sealed devices (see Clause 9; Clause 19 of the 2014

edition);

- Delete the requirement that the COT of the lighting material is higher than 20 K

(see 19.5 of the 2014 edition);

- Add requirements for compliance with industrial standards (see 10.2.1);

- Add requirements for cells (see 10.2.2);

- Change the requirements for cable glands and conduit entries (see 10.2.3; 20.2.2 of

the 2014 edition);

- Change the requirements for gasketed windows (see 10.2.5.2; 20.2.4.2 of the 2014

edition);

- Add documentation requirements for gaskets and seals (see 10.2.6);

- Change the requirements for non-resilient seals (see 10.2.7; 20.2.6 of the 2014

edition);

- Add the requirements for internal fans of restricted-breathing enclosures (see

10.2.9);

- Delete the type test for enclosed break device "nC" and non-sparking device "nA"

(see 22.4 of the 2014 edition);

- Add the preparation of non-incendive component samples (see 11.1.1);

- Change the requirements for dielectric strength test (see 12.1; 22.5.2 of the 2014

edition);

- Delete the type tests for sealed devices, screws, starters, luminaires, ignition

devices and triggers (see Clause 22 of the 2014 edition);

- Delete all cell tests (see 22.11 and 22.12 of the 2014 edition);

- Delete all motor tests (see 22.13 of the 2014 edition);

- Change the requirements for routine tests (see Clause 12; Clause 23 of the 2014

edition);

- Change the requirements for marking (see Clause 13; Clause 24 of the 2014

edition);

- Change the requirements for documentation (see Clause 14; Clause 25 of the 2014

edition);

- Add the requirements of instructions (see Clause 15).

This document uses the redraft law to modify and adopt IEC 60079-15.2017 "Explosive

atmospheres - Part 15.Equipment protection by type of protection 'n'".

The technical differences between this document and IEC 60079-15.2017 and their

reasons are as follows.

- As for the normative references, this document has made adjustments with

technical differences, to adapt to the technical conditions of China. The

adjustments are mainly reflected in Clause 2 "Normative references". The specific

adjustments are as follows.

 Replace IEC 60079-0 with GB/T 3836.1 which modifies and adopts the

international standard (see Clause 1, etc.);

 Replace IEC 60079-7 with GB/T 3836.3 which modifies and adopts the

international standard (see 10.2.2, etc.).

- Delete the column of IEC 60079-15.2017 Table 1 for comparison with the clause

of IEC 60079-0.2011 Ed.6.0, to be consistent with the Chinese standard version.

The following editorial changes have been made to this document.

- In order to be consistent with the existing standard series, change the name of this

document to "Explosive atmospheres - Part 8.Equipment protection by type of

protection 'n'";

- Modify Note 1 in Table 1 about standard version information;

- Add note about GB/T 2900.35 (see Clause 3);

- Change the bibliography.

Attention is drawn to the possibility that some of the elements of this document may be

the subject of patent rights. The issuing authority 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 shall be under the jurisdiction of National Technical Committee 9 on

Explosion Protected Electrical Apparatus of Standardization Administration of China

(SAC/TC 9).

Drafting organizations of this document. Nanyang Explosion Protected Electrical

Apparatus Research Institute Co., Ltd., Shanghai Institute of Quality Inspection and

Technical Research, Shanghai Institute of Process Automation & Instrumentation Co.,

Ltd., Wolong Electric Nanyang Explosion Protection Group Co., Ltd., Censtar Science

& Technology Corp., Ltd., CZ Electric Co., Ltd., Sunleem Technology Incorporated

Company, Warom Technology Incorporated Company.

Main drafters of this document. Wang Jun, Zhang Wentao, Wang Qiaoli, Yang Wenyu,

Qiao Jianwei, Qin Qiling, Jiang Weixin, Zheng Zhenxiao, Wang Yade, Liu Ya, Jiang

Xuqiang.

1 Scope

This document specifies requirements for the construction, testing and marking for

Group II electrical equipment with type of protection "n" which includes; sealed

devices "nC", hermetically sealed devices "nC", non-incendive components "nC" and

restricted breathing enclosures "nR" intended for use in explosive gas atmospheres.

This document applies to electrical equipment where the rated input voltage does not

exceed 15 kV r.m.s. AC or DC including where the internal working voltages of the Ex

product exceeds 15 kV, for example starters for HID luminaires.

2 Normative references

The contents of the following documents, through normative references in this text,

constitute indispensable provisions of this document. Among them, for dated references,

only the edition corresponding to that date applies to this document. For undated

references, the latest edition (including all amendments) applies to this document.

GB/T 3836.1 Explosive atmospheres - Part 1.Equipment - General requirements

(GB/T 3836.1-2021, IEC 60079-0.2017, MOD)

3 Terms and definitions

For the purposes of this document, the terms and definitions given in GB/T 3836.1 and

the following apply.

Device which is so constructed that it cannot be opened during normal service and is

sealed effectively to prevent entry of an external atmosphere.

4 General

In normal operation and in certain regular expected occurrences specified by this

document, the equipment shall not.

Equipment or components which in normal operation produce arcs, sparks or hot

surfaces which otherwise would be capable of igniting a surrounding atmosphere shall

be protected against causing ignition by one or more of the following methods, all of

which provide Equipment Protection Level Gc.

5 Maximum surface temperatures

The maximum surface temperature shall be determined in accordance with the

determination of maximum surface temperature requirements of GB/T 3836.1.

6 Requirements for electrical equipment

Where the electrical circuits within the equipment are not connected directly to the

frame of the equipment or not intended to be connected to the frame in service, the

insulation or separation distance used shall withstand the following tests.

The use of a DC test voltage is allowed as an alternative to the specified AC test voltage

and shall be 170 % of the specified AC r.m.s. test voltage for insulated windings or 140 %

of the specified AC r.m.s. test voltage for situations where air or creepage distance is

the insulating medium.

7 Requirements for non-incendive components

Non-incendive components shall be limited to a maximum rating of 254 V AC, r.m.s.

or DC and 16 A AC, r.m.s. or DC.

8 Requirements for hermetically sealed devices

Hermetically sealed devices, in which the seal is made by fusion of metal to metal or

glass to metal are considered as meeting the requirements for sealed devices without

test.

9 Requirements for sealed devices

Gasket and seals, including poured seals, shall be positioned so that they are not subject

to mechanical damage under normal operating conditions and they shall retain their

sealing properties over the expected life of the device.

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