Search result: GB 50257-2014 (GB 50257-1996 Older version)
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Code for construction and acceptance of electric device for explosion atmospheres and fire hazard electrical equipment installation engineering
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GB 50257-2014
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| GB 50257-1996 | English | RFQ |
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Code for construction and acceptance of electric device for explosion atmospheres and fire hazard electrical equipment installation engineering
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GB 50257-1996
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| Standard ID | GB 50257-2014 (GB50257-2014) | | Description (Translated English) | Code for construction and acceptance of electric device for explosion atmospheres and fire hazard electrical equipment installation engineering | | Sector / Industry | National Standard | | Classification of Chinese Standard | P91 | | Classification of International Standard | 29.140.50 | | Word Count Estimation | 65,667 | | Date of Issue | 12/2/2014 | | Date of Implementation | 8/1/2015 | | Older Standard (superseded by this standard) | GB 50257-1996 | | Quoted Standard | GB 50058; GB 50300; GB 3836.1; GB 3836.2; GB 3836.15; GB 3836.18; GB 4208; GB 12476 | | Issuing agency(ies) | Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China; Ministry of Housing and Urban-Rural Development of the People's Republic of China | | Summary | This Standard applies to the production, processing, handling, transport or storage or may occur during construction and acceptance of gases, vapors, dusts, fibers and fire hazardous explosive mixture of the physical environment of electrical installation |
GB 50257-2014 English name.Code for construction and acceptance of electric device for explosion atmospheres and fire hazard electrical equipment installation engineering
1 General
1.0.1 This specification is formulated to ensure the construction and installation quality of electrical installations in explosion and fire hazardous environments, promote the progress of construction and installation technology, ensure the safe operation of equipment in explosion and fire hazardous environments, and ensure the safety of the country and people's lives and property.
1.0.2 This specification is applicable to the construction and acceptance of electrical installations in environments where gases, vapors, dust, explosive mixtures of fibers and fire-hazardous substances appear or may appear during production, processing, handling, transshipment or storage.
1.0.3 This specification does not apply to the construction and acceptance of electrical installations in the following environments.
1 Underground mine;
2 The environment for the manufacture, use and storage of gunpowder, explosives, primers, fuzes and the production of pyrotechnics;
3 Areas of electrical devices such as electrolysis and electroplating that use electric energy for production and are directly related to the production process;
4 The environment where strong oxidants are used and substances that can ignite by themselves without an external ignition source;
5 Water, land and air transportation vehicles and offshore and land oil well platforms;
6 Nuclear islands of nuclear power plants;
7 Heating, air conditioning, cooking, laundry and similar plumbing systems fueled by flavored natural gas;
8 medical room;
9 catastrophic accident.
1.0.4 The construction and acceptance of electrical installations in explosive and fire-hazardous environments shall not only comply with this code, but also comply with the current relevant national standards.
2 terms
2.0.1 Explosive atmosphere explosive atmosphere
Under atmospheric conditions, the mixture of flammable substances in the form of gas, vapor, dust, mist, fibers or flying flocs and air, after being ignited, can maintain the environment in which the combustion propagates itself.
2.0.2 Explosive dust atmosphere explosive dust atmosphere
Under atmospheric conditions, the mixture of combustible substances in the form of dust, fibers or flying flocs and air, after being ignited, can maintain an environment in which combustion spreads by itself.
2.0.3 Explosive gas atmosphere explosive gas atmosphere
Under atmospheric conditions, the mixture of flammable substances in the form of gas or vapor and air, after being ignited, can maintain the environment in which the combustion propagates itself.
2.0.4 Hazardous area
An area where explosive mixtures are present or are expected to be present in quantities sufficient to require precautionary measures for the construction, installation and use of electrical equipment.
2.0.5 zone 0 zone 0
Environments where explosive gas mixtures are present continuously or for a long period of time.
2.0.6 zone 1 zone 1
Environments where explosive gas mixtures may be present during normal operation.
2.0.7 zone 2 zone 2
An environment in which explosive gas mixtures are unlikely to occur during normal operation, or where explosive gas mixtures exist only for a short period of time if they occur.
2.0.8 zone 20 zone 20
Combustible dust clouds in the air are continuously or chronically or frequently present in areas with explosive atmospheres.
2.0.9 zone 21 zone 21
During normal operation, airborne combustible dust clouds are likely to occasionally occur in areas of explosive atmospheres.
2.0.10 zone 22 zone 22
During normal operation, combustible dust clouds in the air are generally unlikely to appear in areas with explosive dust atmospheres, and even if they do, the duration is short.
2.0.11 Explosion-proof type type of protection
Various specific measures are taken for electrical equipment to prevent ignition of surrounding explosive atmospheres.
2.0.12 Intrinsic safety type "i" intrinsic safety "i"
A type of explosion protection that limits exposure to electrical energy inside equipment and interconnecting wires in an explosive gas atmosphere to below that which could cause ignition by sparks or thermal effects.
2.0.13 Intrinsically safe circuit intrinsically-safe circuit
Under normal operation and specified fault conditions, any electric spark or any thermal effect generated cannot ignite the circuit in the specified explosive gas atmosphere.
2.0.14 intrinsically safe electrical equipment intrinsically-safe electrical appa-ratus
All internal circuits are electrical equipment with intrinsically safe circuits.
2.0.15 Associated electrical equipment associated electrical apparatus
Electrical equipment equipped with intrinsically safe circuits and non-intrinsically safe circuits, and constructed so that non-intrinsically safe circuits cannot adversely affect intrinsically safe circuits.
2.0.16 Positive pressure shell type "P" pressurization "P"
An explosion-proof type that prevents the entry of external explosive gases by maintaining the pressure of the protective gas inside the enclosure or in the room higher than the external atmospheric pressure.
2.0.17 Oil immersion type "o" oil immersion "o"
A type of explosion protection in which electrical equipment or components of electrical equipment are immersed in a protective liquid so that the equipment cannot ignite explosive gases on the liquid surface or outside the enclosure.
2.0.18 "n" type electrical equipment type of protection "n"
An explosion-proof type, the explosion-proof type of electrical equipment, in normal operation and under some abnormal conditions specified in this part, can not ignite the surrounding explosive gas.
2.0.19 flameproof enclosure "d" flameproof enclosure "d"
An explosion-proof type of electrical equipment, the shell of which can withstand the internal explosion of the explosive mixture entering the shell through any joint surface or structural gap without damage, and will not cause an explosive explosion formed by one or more gases or vapors outside. Ignition of gaseous atmospheres.
2.0.20 Increased safety type "e" increased safety "e"
An explosion-proof type of electrical equipment, that is, some additional measures are taken for electrical equipment to improve its safety and prevent the possibility of dangerous temperatures, arcs and sparks under normal operation or specified abnormal conditions.
Note. 1 This form of protection is denoted by "e", and additional measures are those that comply with the requirements of this standard.
2 The definition of increased safety "e" does not include equipment that produces sparks or arcs under normal operating conditions.
3 Basic Regulations
3.0.1 The installation of electrical devices in explosive and fire-hazardous environments shall be carried out in accordance with the approved design documents.
3.0.2 The transportation and storage of equipment and equipment shall meet the requirements of product technical documents.
3.0.3 The equipment and equipment used shall have qualified certificates. The equipment should have a nameplate, and the explosion-proof electrical equipment should have an explosion-proof mark.
3.0.4 After the equipment and equipment arrive at the site, they shall be inspected for acceptance and shall comply with the following regulations.
1 The packaging and sealing should be good;
2 Open the box for inspection and inventory. The model, specification and explosion-proof mark should meet the design requirements, and the accessories, accessories and spare parts should be in good condition;
3 The technical documents of the product should be complete;
4 The nameplate of the explosion-proof electrical equipment shall be marked with the "explosion-proof certificate number" issued by the national inspection unit;
5 The appearance inspection of the equipment should be free from damage, corrosion and moisture.
3.0.5 Construction safety technical measures shall meet the requirements of this code and product technical documents. In expansion and reconstruction projects, safety regulations related to construction in the safety production (operation) regulations of the production plant should be followed. For important processes, special safety technical measures and construction operation instructions should be formulated in advance.
3.0.6 The construction of construction projects related to the installation of electrical installations in explosion and fire hazardous environments shall comply with the following regulations.
1 The engineering quality of buildings and structures shall comply with the relevant provisions of the current national standard "Unified Standards for Construction Quality Acceptance of Construction Engineering" GB 50300.When there are special requirements for equipment or design, the special requirements shall be complied with.
2 Before the equipment is installed, the construction project shall meet the following conditions.
1) The foundation and structure should meet the design requirements and pass the acceptance check;
2) The indoor ground foundation should be constructed, and the ground elevation should be marked on the wall;
3) The embedded parts and reserved holes shall meet the design requirements, the embedded electrical pipeline shall not be missed or blocked, and the embedded parts shall be firm;
4) The plastering and decoration works that may damage or seriously pollute electrical installations should be completed;
5) The site should be cleaned up;
6) Doors and windows should be installed.
3 After the electrical installations in explosion and fire hazardous environments are installed, before they are put into operation, the building installation project shall comply with the following regulations.
1) Defect repair and decoration works should be completed;
2) The secondary grouting and plastering work should be completed;
3) The explosion-proof ventilation system and the leakage control of explosives shall meet the design requirements and be qualified in operation;
4) The construction of the projects that cannot be carried out after receiving power and affect the safety of operation shall be completed and passed the acceptance inspection;
5) Architectural lighting should be delivered for use.
3.0.7 The fasteners used for equipment installation, except the anchor bolts, iron fasteners and brackets should be galvanized products.
3.0.8 The zoning of explosive gas atmospheres, explosive dust atmospheres and fire-hazardous environments shall comply with the relevant provisions of the current national standards "Code for Design of Electric Power Installations in Explosive Hazardous Environments" GB 50058 and "Code for Fire Protection Design of Buildings" GB 50016.
3.0.9 The type, level, group, environmental conditions and special signs of explosion-proof electrical equipment shall meet the design requirements.
3.0.10 Explosion-proof electrical equipment should have "Ex" mark and a nameplate indicating the type, level and group of explosion-proof electrical equipment, and the explosion-proof certificate number should be marked on the nameplate.
4 Installation of explosion-proof electrical equipment
4.1 General provisions
4.1.1 The installation of explosion-proof electrical equipment shall comply with the current national standards "Electrical Equipment for Explosive Gas Atmospheres Part 15.Electrical Installation in Hazardous Locations (Except Coal Mine)" GB 3836.15 and "Electrical Equipment for Combustible Dust Environments" GB 12476 Regulation.
4.1.2 Explosion-proof electrical equipment should be installed on a support made of metal. The support should be firm, and the fixing bolts of electrical equipment with vibration should have anti-loosening devices.
4.1.3 After the internal wiring of the junction box of explosion-proof electrical equipment is fastened, the electrical clearance and creepage distance between the exposed live parts and between the metal casing and the metal casing shall not be less than the provisions in Appendix A of this specification.
4.1.4 After the cable inlet of explosion-proof electrical equipment is connected with the lead-in of cables and wires, the integrity of the cable lead-in device and the tightness of the elastic sealing ring shall be maintained, and the pressing element shall be tightened with tools, and the wire inlet shall be maintained seal. The elastic sealing rings, metal gaskets, and blocking parts of the redundant line inlets should be complete, and the installation should be tight and the seal should be good.
4.1.5 Transparent plastic parts or other parts shall not be scrubbed with solvents.
4.1.6 The button of the emergency exhaust fan shall be installed separately at a position convenient for operation, and shall have a conspicuous special mark.
4.1.7 The installation of lamps shall comply with the following regulations.
1 The type, model and power of lamps shall meet the requirements of design and product technical conditions, and shall not be changed arbitrarily;
2 The screw-type bulb should be screwed tightly, the contact should be good, and it should not be loose;
3 The outer cover of the lamp should be complete and the bolts should be fastened.
4.1.8 The protection settings for electrical equipment in explosive hazardous environments should meet the design requirements.
4.2 Installation of flameproof electrical equipment
4.2.1 Before installation of flameproof electrical equipment, the following checks shall be carried out.
1.The type and specification of the equipment should meet the design requirements, and the nameplate and explosion-proof marks should be correct and clear;
2.The casing of the equipment should be free from cracks and damages;
3 The flameproof structure and clearance shall meet the requirements;
4 The fastening bolts on the joint surface should be complete, the anti-loosening facilities such as spring washers should be complete and intact, and the spring washers should be flattened;
5 The sealing gasket should be complete and intact, without aging deformation, and should meet the technical requirements of the product;
6 Transparent parts should be clean and free from damage;
7.The moving parts should be free from collision and friction;
8.The terminal board and insulating parts should not be broken, the cover of the terminal box should be fastened, and the electrical clearance and creepage distance should meet the requirements;
9 The ground sign and the ground screw should be in good condition.
4.2.2 Disassembly and assembly of flameproof electrical equipment shall comply with the following regulations.
1 Protect the explosion-proof surface from damage;
2 There should be no trachoma and mechanical scars on the explosion-proof surface;
3 The explosion-proof surface without electroplating or phosphating layer can use non-condensing grease or anti-rust oil, and paint is not allowed;
4 There shall be no rust layer on the explosion-proof surface during assembly;
5 The fastening bolts of the flameproof joint surface shall not be replaced arbitrarily, and the spring washers shall be complete;
6 For threaded flameproof structures, the minimum number of engagement threads and minimum engagement depth of the threads shall comply with the provisions in Table 4.2.2.
Table 4.2.2 Minimum Engagement Number and Minimum Engagement Depth of Threaded Flameproof Structure Thread
4.2.3 The gap between the shaft and the shaft hole of the flameproof motor, the fan and the end cover should be even and free of friction, and there should be no friction under normal working conditions.
4.2.4 For flameproof electrical equipment that generates sparks or arcs during normal operation, its electrical interlocking device should be reliable; when the power is turned on, the cover should not be opened, and the power should not be turned on after the cover is opened. For the shell fastened by bolts, the warning sign of "open the cover after power failure" should be checked, and it should be intact.
4.2.5 The inspection and installation of flameproof pins shall comply with the following regulations.
1 When the plug is inserted, the grounding or zero contact should be connected first; when the plug is pulled out, the main contact should be disconnected first;
2 The plug should be inserted or pulled out when the switch is in the breaking position, and the switch should be closed after the plug is inserted;
3 The creeping device to prevent sudden pull-off should be intact and reliable, and must not be loosened.
4.3 Installation of increased safety and "n" type electrical equipment
4.3.1 Before installation of increased safety type and "n" type electrical equipment, the following checks shall be carried out.
1.The type and specification of the equipment should meet the design requirements, and the nameplate and explosion-proof marks should be correct and clear;
2 The shell and light-transmitting parts of the equipment should be free from cracks and damages, and the protection level should meet the requirements;
3 The fastening bolts of the equipment should have anti-loosening measures, there should be no looseness and corrosion, and the junction box cover should be fastened;
4 The protective devices and accessories should be complete and in good condition.
4.4 Installation of positive pressure enclosure type "P" electrical equipment
4.4.1 Before installation of positive pressure enclosure type "P" electrical equipment, the following checks shall be carried out.
1.The type and specification of the equipment should meet the design requirements, and the nameplate and explosion-proof marks should be correct and clear;
2 The shell and light-transmitting parts of the equipment should be free from cracks and damages;
3 The fastening bolts of the equipment should have anti-loosening measures, there should be no looseness and corrosion, and the junction box cover should be fastened;
4 The protective devices and accessories should be complete and in good condition;
5 The sealing gasket should be complete and intact, without aging deformation, and should meet the requirements of product technical conditions.
4.4.2 The air or gas entering the ventilation, gas charging system and electrical equipment should be clean and must not contain explosive mixtures and other harmful substances.
4.4.3 The gas discharged during the ventilation process should not be discharged into the explosive atmosphere. When it is discharged into the explosive gas environment Zone 2, measures should be taken to prevent sparks and hot particles from blowing out from the electrical equipment and its ventilation system.
4.4.4 The electrical interlocking device of the ventilation and inflation system shall operate normally according to the procedure of ventilation first, then power supply, and power failure first, then wind shutdown. Before the electrical equipment is energized and started, the volume of the protective gas in the enclosure shall not be less than the sum of the minimum gas exchange volume specified in the product technical conditions and 5 times the volume of the connected pipeline.
4.4.5 The wind pressure and air pressure values in electrical equipment and ventilation and air charging systems during operation shall meet the requirements of the design documents.
4.4.6 The sparks and arcs inside the positive pressure enclosure type "P" electrical equipment in operation should not be blown out from the gap or air outlet.
4.4.7 Ventilation ducts should be well sealed.
4.5 Installation of oil-immersed type "o" electrical equipment
4.5.1 Before installation of oil-immersed type "o" electrical equipment, the following checks shall be carried out.
1.The type and specification of the equipment should meet the design requirements, and the nameplate and explosion-proof marks should be correct and clear;
2 The casing of electrical equipment should be free from cracks and damages;
3 The oil tank and oil mark of electrical equipment shall not have any cracks, oil leakage or oil leakage defects. The oil level should be within the range of the oil mark line;
4 The oil discharge hole and the exhaust hole should be unobstructed and there should be no sundries.
4.5.2 The installation of oil-immersed type "o" electrical equipment should be vertical, and its inclination should not be greater than 5°.
4.5.3 The maximum temperature rise of the oil surface of the oil-immersed "o" type electrical equipment shall not exceed the requirements in Table 4.5.3.
Table 4.5.3 Maximum temperature rise of oil surface of oil-immersed "o" electrical equipment
4.6 Installation of intrinsically safe "i" electrical equipment
4.6.1 Before installation of intrinsically safe type "i" electrical equipment, the following checks shall be carried out.
1.The type and specification of the equipment should meet the design requirements, and the nameplate and explosion-proof marks should be correct and clear;
2 The casing should be free from cracks and damage;
3 The product nameplates of intrinsically safe "i" electrical equipment and related electrical equipment shall have explosion-proof marks, explosion-proof certificate numbers and relevant electrical parameters; the combination of intrinsically safe "i" electrical equipment and related electrical equipment shall comply with the current national Relevant provisions of the standard "Explosive Atmospheres Part 18.Intrinsically Safe Systems" GB 3836.18;
4 All parts, components and circuits of electrical equipment should be connected reliably and in good performance.
4.6.2 The power transformer in the associated electrical equipment shall meet the following requirements.
1 The shield between the iron core and the winding of the transformer should be reliably grounded at one point and only at one point;
2 The rated current of the fuse of the power transformer directly connected to the external power supply system shall meet the design requirements.
4.6.3 The battery type and specification of intrinsically safe "i" electrical equipment with independent power supply shall comply with the regulations on the nameplate of the electrical equipment, and batteries of other types and specifications shall not be used instead.
4.6.4 The type, specification and length of the connecting wires or cables between the intrinsically safe "i" electrical equipment and associated electrical equipment, as well as the required parameters, shall meet the design requirements.
4.7 Installation of dust explosion-proof electrical equipment
4.7.1 Before installing dust explosion-proof electrical equipment, the following checks should be carried out.
1 The explosion-proof mark, enclosure protection level and temperature group of the equipment shall be compatible with the explosive dust environment;
2.The model and specification of the equipment should meet the design requirements, and the nameplate and explosion-proof marks should be correct and clear;
3 The casing of the equipment should be smooth, free from cracks, damage, pits or grooves, and should have sufficient strength;
4 The fastening bolts of the equipment should be free from looseness and corrosion;
5.The joint surface of the shell of the equipment should be tightly fastened, the sealing gasket should be intact, the dust-proof seal between the rotating shaft and the shaft hole should be tight, and the transparent parts should be free of cracks.
4.7.2 The equipment should be installed firmly, the wiring should be correct, the contact should be good, the ventilation hole should not be blocked, and the electrical clearance and creepage distance should meet the technical requirements of the equipment.
4.7.3 When the equipment is installed, the integrity and sealing performance of the casing and line-entry device shall not be damaged.
4.7.4 The level and group of explosion-proof electrical equipment should not be lower than the level and group of the explosive gas mixture in the explosive gas environment, and should meet the requirements of the design documents. Electrical equipment installed in an explosive dust environment shall take measures to prevent fire hazards caused by hot surfaces pointing to combustible dust layers. The maximum surface temperature of Class III electrical equipment should be selected according to the current relevant national standards. The structure of electrical equipment shall meet the requirements that the electrical equipment shall not reduce the explosion-proof performance under the specified operating conditions.
4.7.5 After the dust explosion-proof electrical equipment is installed, the adjustment and trial operation of the protection device shall be carried out according to the technical requirements of the product.
5 Electrical circuits for explosive atmospheres
5.1 General provisions
5.1.1 The laying method and path of electrical lines shall meet the design requirements. When there is no specific requirement in the design, the following provisions shall be complied with.
1 Electrical lines should be laid in an environment with lesser risk of explosion or in a place far away from the release source. And should meet the following requirements.
5.2.3 Explosion-proof electrical equipment,...
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