GB 12476.5-2013 PDF English
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Electrical apparatus for use in the presence of combustible dust -- Part 5: Protection by enclosures “tD”
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GB 12476.5-2013: PDF in English GB 12476.5-2013
Electrical apparatus for use in the presence of combustible dust.Part 5. Protection by enclosures "tD"
ICS 29.260.20
K35
National Standards of People's Republic of China
Electrical equipment for combustible dust atmospheres
Part 5. Housing protection type "tD"
Electricalapp Русский
Part 5. Protectionbyenclosures "tD"
(IEC 61241-1..2004, Electricalapp)
combustibledust-Part 1. Protectionbyenclosures "tD", IDT)
2013-12-17 release
2014-11-14 implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
China National Standardization Management Committee released
Preface
The entire contents of this section are mandatory.
GB 12476 "Electrical Equipment for Combustible Dust Environment" is divided into several parts.
- Part 1. General requirements;
- Part 2. Selection and installation;
- Part 3. Classification of hazardous places in the presence or presence of combustible dust;
- Part 4. Intrinsically safe "iD";
- Part 5. enclosure protection type "tD";
- Part 6. Type of enclosure protection "mD";
- Part 7. Positive pressure protection type "pD";
- Part 8. Test methods - Method for determining the minimum ignition temperature of dust;
- Part 9. Test methods - Determination of resistivity of dust layer;
- Part 10. Test methods - Determination of minimum ignition energy for dust and air mixtures;
This part is part 5 of GB 12476.
This part is drafted in accordance with the rules given in GB/T 1.1-2009.
IEC 61241-1..2004 "Electrical equipment for combustible dust atmospheres" Part 1. Protective enclosure
Type "tD" ".
In this part of the normative reference to the international documents have a consistent correspondence between the following documents.
GB 12476.1-2013 Electrical equipment for combustible dust atmospheres - Part 1. General requirements (IEC 61241-0..2004,
MOD).
This part is made by China Electrical Equipment Industry Association.
This part of the national explosion-proof electrical equipment Standardization Technical Committee (SAC/TC9) centralized.
This part of the main drafting unit. Nanyang explosion electrical research institute.
This part of the main participating units. National Explosion-proof electrical products Quality Supervision and Inspection Center, Shenzhen Tean Electronics Co., Ltd., Huarong Group
Limited liability company, Henan Huanghe Explosion-proof Crane Co., Ltd., Changzhou Yuhua Electronic Equipment Co., Ltd., is a explosion-proof Electric Co.,
The main drafters of this part. Wang Jun, Li Shuzhao, Chen Rui, Hu Linzhong, Wang Ping, Huang Jianfeng, Li Jiang, Zhou Jinliang.
introduction
Many of the dust produced in the production, processing, transportation and storage is flammable. If the dust and air are mixed in appropriate proportions, point
The dust can burn quickly to produce a huge explosion pressure. In places where such combustible materials may be present, they are usually required
Explosion-proof electrical equipment, and therefore must take appropriate precautions to ensure that all electrical equipment is adequately protected to reduce the ignition of the external
The possibility of an explosive environment. Potential sources of ignition in electrical equipment include arcs, sparks, hot surfaces, and friction sparks.
Dangerous quantities of dust, fibers and flying places in the air are dangerous places and are divided into three hazards according to the hazard level
area.
In general, one of the following two methods is used to ensure the electrical safety of electrical equipment. a method (if practicable)
Installed in a dangerous place, another method in accordance with the electrical equipment used in the recommended method of design, installation and maintenance.
Electrical equipment may ignite flammable dust through the following main ways.
- The surface temperature of the electrical equipment is higher than the minimum ignition temperature of the relevant dust. Dust ignition temperature and dust performance, dust exists
State, the thickness of the dust layer and the geometry of the heat source;
Arcs or sparks of electrical components such as switches, contacts, rectifiers, brushes and similar parts;
Accumulated electrostatic discharge;
--- Radiant energy (eg electromagnetic radiation);
--- mechanical sparks related to electrical equipment, friction spark or friction heat.
In order to avoid the risk of ignition should do the following.
- the temperature of the surface of electrical equipment that may accumulate dust or may be in contact with the dust cloud shall be maintained at the temperature limits specified in this section
the following;
- any parts that produce spark or parts whose temperature is higher than the above temperature limit
● placed in a shell that is sufficient to prevent dust from entering;
• limit the energy of the circuit to avoid the generation of arcs, sparks or temperatures that can ignite flammable dust;
--- avoid any other ignition source.
If the electrical equipment is operated under its rated conditions and is installed and maintained in accordance with the applicable regulations or requirements,
Flow and internal short-circuit faults and other electrical faults, the protection method specified in this section will meet the required level of safety. especially important
Is to limit the severity and duration of internal or external failures to values that can not maintain damage to the electrical equipment.
Hazardous places in the use of several electrical equipment explosion-proof technology. This part describes the safety characteristics of the explosion-proof type, which stipulates the mining
Take the request. To ensure the safety of electrical equipment in hazardous locations, it is most important to comply with standard selection and installation procedures.
In this section, the shell protection "tD" specifies two different types. Type A and Type B, both of which have the same protection
Level.
Type A and Type B are common in both types and are not required to be confused by both types of equipment requirements and selection/installation.
begging. They use a different method, the main difference is.
Type A Type B
Mainly prepared according to the performance requirements mainly prepared according to the normative requirements
The maximum surface temperature is in the case where the thickness of the relevant dust layer is 5 mm
Under the test, and the installation procedure requires the temperature of the dust surface and the ignition temperature
Between the safety margin of 75K
The maximum surface temperature is in the case where the thickness of the relevant dust layer is 12.5 mm
Under the test, and the installation procedure requires the temperature of the dust surface and the ignition temperature
The safety margin is 25K
Method for determining dust entry According to GB 4208-IP code, the method for measuring dust entry is determined by the thermal cycle test
Electrical equipment for combustible dust atmospheres
Part 5. Housing protection type "tD"
1 Scope
This part of GB 12476 is applicable to electrical equipment which is protected by a housing and a restricted surface temperature in a flammable dust environment. In the ring
The presence of flammable dust can cause a fire or explosion hazard. This section specifies the design, construction and testing of electrical equipment
Claim.
This part is a supplement to the general requirements of GB 12476.1.
Note. GB 12476.2 gives guidelines for the selection and installation of electrical equipment. Electrical equipment within this section may also comply with other standards (eg GB 3836.1)
The supplementary requirements.
To prevent ignition is mainly to limit the shell and can be in contact with other surfaces of the dust surface of the highest surface temperature, the use of "dust" or "dust" outside
Shell to limit dust entry.
Electrical equipment used in environments where combustible gases and combustible dust may appear simultaneously or separately, requiring additional
Plus protection measures.
When the electrical equipment must meet other environmental requirements, such as water and corrosion and the need to use other protection methods, the protection method
Should not have an adverse effect on the integrity of the shell.
This part does not apply to those who do not need the atmosphere of oxygen can burn the fire explosives dust or spontaneous combustion material.
This part does not apply to electrical equipment that is hazardous to methane and/or flammable dust and coal mine ground equipment.
This section does not take into account the risk of flammability or toxic gases volatilized from dust.
2 normative reference documents
The following documents are indispensable for the application of this document. For dated references, only the dated edition applies to this article
Pieces. For undated references, the latest edition (including all modifications) applies to this document.
GB 4208-2008 enclosure protection class (IP code) (IEC 60529..2001, IDT)
IEC 61241-0..2013 Electrical equipment for combustible dust atmospheres - Part 0. General requirements (Electrical finger)
useinthepresenceofcombustibledust Part0. Generalrequirements)
3 terms and definitions
IEC 61241-0 and the following terms and definitions apply to this document.
3.1
Shell protected "tD" dustignitionprotectiontype "tD"
All electrical equipment is protected from the enclosure to prevent dust or dust from being ignited.
4 structure
As a supplement to IEC 61241-0, clause 4, the following requirements apply.
20 zone equipment.
If the enclosure of the equipment complies with the requirements of this part, and all seals that prevent dust from entering are not subjected to moving parts (eg shafts,
Rod), the housing is considered safe and reliable and the fault analysis is only applicable to the circuit.
5 Type A and Type B
This section specifies two different types of Type A and Type B. These two types have the same level of safety.
6 Additional requirements for electrical equipment protected by Type A enclosure in Zone 20, Zone 21 and Zone 22
Protection class IP6X dusty enclosure should be allowed for.
--- 20 area;
--- 21 area;
--- Zone 22 with conductive dust.
Protection class IP5X dustproof enclosure should be allowed for.
--- no conductive dust in the 22 area.
At present, there is no additional requirement for Type A in IEC 61241-0 and this part.
7 Supplementary requirements for electrical equipment protected in Class B or Zone 21 with Type B enclosure
7.1 joint surface
7.1.1 plane joint surface
The plane joint (see Figure 1) should have a minimum engagement width from inside to outside of the housing, and the maximum allowable clearance between the surfaces (see Table 1
).
Table 1 plane joint surface
The minimum joint width W/mm 5 22 of the plane joint
The maximum allowable clearance between the surfaces of the joint surface is G/mm 0.05 0.22
Note. For the width of the joint between 5mm ~ 22mm, the width of the joint surface is greater than 5mm, for each additional 1mm, the gap can be increased 0.01mm.
Figure 1 plane joint surface
7.1.2 Stop joint surface
(See Fig. 2). If the axial passage length L and the radial path length W are not less than 1.2 mm, then the diameter of the gap
As shown in Table 1, the plane joint surface gap. The radial joint W of the stop joint surface does not exceed the maximum allowable distance between the planar joint surfaces shown in Table 1
Gap G.
Figure 2 mouth joint surface
7.1.3 Pad bonding surface
Table 2 shows the requirements for the liner engagement surface (see Figure 3).
Figure 3 liner engagement surface
Table 2 liner engagement surface
Maximum opening size O/mm 305 915> 915
Minimum effective width required for liner engagement surface W/mm 3 4.8 9.5
The maximum opening size between 305mm ~ 915mm, the maximum opening size greater than 305mm for each additional 1mm, the pad surface
The effective width should be increased by 0.003mm.
7.2 Joystick, mandrel or shaft
7.2.1 General
For equipment used in zones 20 and 21, the dust should not be relied solely on a rotating contact seal, which shall comply with the details of Table 3 and Table 4
Design requirements, and 8.2.1 test should not be installed when the rotating contact seals.
7.2.2 Rotating contact seal
If the rotary contact seal method is used, the equipment shall comply with the detailed design requirements of Tables 3 and 4 and shall not be carried out during 8.2.1 dust test
A rotating contact seal should be installed.
7.2.3 Shafts
When the rotational speed of the transmission power is 100 r/min or more (see Fig. 4), the length of the passage from the inside to the outside of the housing shall be in accordance with Table 3
Claim.
Figure 4 Rotation speed equal to or greater than 100r/min
Table 3 Rotation speed equal to or greater than 100r/min
Minimum path length of the shaft L/mm 12.5 38.5
Maximum allowable diameter gap D2-D1/mm 0.26 0.57
The length of the path of the shaft is between 12.5mm and 38.5mm, and the length of the passage is more than 12.5mm. For each additional diameter of 1mm,
The gap can be increased by 0.012mm.
NOTE. The minimum length of the passage may include the inner and outer flanges of the bearing chamber.
7.2.4 joystick
Less than 100r/min rotary motion or axial movement of the joystick, mandrel or shaft should be used 3-pin full thread of the threaded joint surface,
Or the minimum path length listed from Table 4 below from the inside of the enclosure to the outside.
Table 4 Rotation axis with speed less than 100r/min
Minimum path length of joystick, shaft or shaft L/mm 12.5 25.5
Maximum allowable diameter gap D2-D1 (W)/mm 0.13 0.21
The length of the path of the joystick, mandrel or shaft is between 12.5mm and 25.5mm, and the length of the path is greater than 12.5mm.
1mm, the maximum diameter gap can be increased by 0.006mm.
7.3 screw gap
(DS-DH) between the unthreaded portion (N) of the bolt and the clearance hole on the housing, the bolts penetrating the housing wall,
Should not exceed 0.26mm, the passage length (L) should not be less than 12.5mm (see Figure 5).
Figure 5 screw gap
8 check and test
8.1 General
In addition to the inspection and test requirements of IEC 61241-0, the following shall apply.
8.2 Type test
8.2.1 shell dust test
8.2.1.1 Overview
Two effective dust-proofing measures have been adopted based on possible environmental conditions (eg dust site type and dust conductivity). "dusty
Type "and" dustproof ".
Note. The required effective dust level, see GB 12476.2-2010.
The following tests shall take into account the effects of the presence of flammable dust during the acceptance of the equipment.
When using flammable dust for testing, safety measures shall be prescribed by the inspection agency or other relevant agency.
8.2.1.2 Type A dusty equipment
Including the rotating motor, including a variety of shells should meet the requirements of GB 4208 IP6X requirements.
8.2.1.3 Type A dustproof equipment
Including the rotating motor, including a variety of shells should be consistent with GB 4208 provisions of the IP5X test and qualified requirements.
8.2.1.4 B-type dust-tight equipment
8.2.1.4.1 Thermal cycling test
a) The electrical equipment shall be placed in a test chamber of sufficient size so that the dust-air mixture can surround the sample during the test
By the loop.
The proper amount of dust and air mixture is continuously circulated in the test chamber by means of auxiliary equipment and continuously during the entire test period
Into the test chamber. The size of the dust particles used should be through the ASTM 100 screen (sieve width of about 0.15mm). its
Approximately 22% of the dust can pass through the ASTM.200 screen (sieve width of about 0.075mm).
b) In the above-mentioned test, the equipment shall be operated at the rated load to reach the maximum temperature and then cooled to near room temperature
only. Hot and cold cycle for at least 6 cycles, duration of at least 30h.
Note 1. The maximum temperature under load can be achieved by other means than the rated load. For a junction box like no obvious thermal effect
(E.g., switches) that can simulate atmospheric pressure changes to produce the desired "respiration".
Note 2. The test chamber is heated to 40 ° C and maintained at this temperature for about 1 hour. The test chamber is then cooled to 20 ° C and maintained at this temperature for 1 h. This is a suitable simulation
Method of atmospheric pressure change.
When the specified number of heating and cooling cycles is completed, turn off the equipment that produces the dust-air mixture and carefully clean off the stack
In the dust on the surface of the shell, and pay attention to avoid other dust into the shell.
Do not purge dust with air blowing or vacuum cleaning.
Then open the case and carefully check the degree of dust entry (if any).
8.2.1.4.2 Conformity criteria
No visible dust enters the shell. The dust on the joint surface should not be considered unacceptable.
8.2.1.5 Type B dustproof equipment
8.2.1.5.1 Thermal cycling test
The test procedure shall be in accordance with 8.2.1.4.1, but the hot and cold cycle shall be carried out for at least two cycles for a duration of at least 10 hours.
8.2.1.5.2 Conformity criteria
No visible dust enters the shell. The dust on the joint surface should not be considered unacceptable.
8.2.2 Heat resistance test
8.2.2.1 Type A equipment
This test shall be carried out in accordance with 23.4.4.1 of IEC 61241-0..2013.
8.2.2.2 Type B equipment
The test method shall be in accordance with the provisions of 23.4.4.1 to 23.4.4.3 of IEC 61241-0..2013, but the equipment shall be of the same
Of the maximum amount of dust cover as an additional requirement. Another approach is to cover 12.5mm thick dust layer paste in the top of the electrical equipment mold
The state of the dust to be formed.
Note. The paste should consist of 45% dust (eg wheat flour) and 55% water. The temperature value should be measured after the paste is dried.
9 logo
Use the provisions of Chapter 29 of IEC 61241-0..2013 with the following exceptions.
29.2 Item 4.
The symbol used for the protection type shall be "tD" (enclosure protection type).
29.2 Item 5.
In the device can be used in front of the area with the prefix prefix, A plus prefix "A" and B plus prefix "B".
29.2 Item 6.
Type B does not require IP rating.
references
[1] GB 2900.35 Electrical terminology Equipment for explosive atmospheres
Explosive atmospheres - Part 1. General requirements for equipment
[3] GB 3836.3-2010 Explosive atmospheres Part 3. Equipment protected by increased safety "e"
[4] GB 3836.4-2010 Explosive atmospheres Part 4. Equipment protected by intrinsically safe "i"
[5] GB 12476.2-2010 Electrical equipment for combustible dust atmospheres - Part 2. Selection and installation
[6] GB 12476.3-2007 Electrical equipment for combustible dust atmospheres - Part 3. Flammable dust with or in the presence of flammable dust
Classification of Hazardous Locations
[7] GB 12476.8-2010 Electrical equipment for combustible dust atmospheres - Part 8. Test methods - Determination of dust minimum ignition temperature
Degree of method
[8] IEC 60093. 1980Methodsoftestvolumeresistivityandsurfaceresistivityofsolidelectrical
insulatingmaterials
[9] IEC 60192..2001Low-pressurevapourlamps-Performancespecifications
[10] IEC 60216-1..2001Electricalinsulating-propertiesofthermalendurance-Part 1. Ageing
proceduresandevaluationoftestresults
[11] IEC 60216-2..1990Guidefortdeterminationofthermalendurancepropertiesofelectrical
insulatingmaterials-Part 2. Choiceoftestcriteria
[12] IEC 60243-1..1998Electricalstrengthofinsulatingmaterials-Testmethods-Part 1.
Testsatpowerfrequencies
[13] IEC 60662. 1980 High-pressureodiumvapourlamps
[14] IEC 60943-3..1999Low-voltageswitcherandcontrolgear-Part 3. Switches, disconnec-
tors, switch-disconnectorsandfuse-combinationunits
[15] ISO 178..2001Plastics-Determinationofflexuralproperties
[16] ISO 527 (alparts) Plastics-Determinationoftensileproperties
[17] ISO 4225..1994Airquality-Generalaspects-Vocabulary
1-14216
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Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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