GB 3836.5-1987 Explosion-proof electrical equipment for explosive environments Positive pressure electrical equipment "p"
Some standard content:
1 Introduction
National Standard of the People's Republic of China
Explosion-proof electrical equipment for explosive atmospheres
Positive pressure electrical equipment "p"
Electrical apparatus for explosive atmospheresPressurized electrical apparatus"\ p\1.1 This standard applies to positive pressure electrical equipment without flammable gas release sources inside the enclosure UDC621.3-78: 622
.81
GB3836.5-87||tt| |1.2 In addition to complying with this standard, positive pressure electrical equipment must also comply with the relevant provisions of GB3836.1-83 "General Requirements for Explosion-Proof Electrical Equipment for Explosive Environments"
2 Terms
2.1 Positive pressure enclosure
An enclosure that keeps the pressure of the internal protective gas higher than the pressure of the surrounding explosive environment and prevents external mixtures from entering. 2.2 Positive pressure electrical equipment "p"
Electrical equipment with a positive pressure enclosure. Equipment.
2.3 Ventilation
The process of passing a sufficient amount of protective gas through the positive pressure shell and pipeline to reduce the concentration of the explosive mixture to below the lower explosion limit. 2.4 Positive pressure ventilation
Process of protective gas. A method of continuously passing the positive pressure shell to maintain positive pressure in the shell. 2.5 Positive pressure compensation
When each exhaust port is closed, the inevitable leakage of the protective gas in the positive pressure shell and pipeline is compensated to keep the shell. Method of maintaining positive pressure inside.
2.6 Protective gas
Air or non-combustible gas for dilution, ventilation, pressurization or ventilation. 3 Positive pressure enclosure and its connecting pipes
3.1 The protection level of the positive pressure shell and its connecting pipes must be no less than IP40, and must be able to prevent any sparks and hot particles from being ejected from the shell or pipes. The exhaust port should generally be located in a non-explosive hazardous location; if measures can be taken to be effective. When the ground is installed to prevent sparks or hot particles from blowing out, the exhaust port can be located in a place with a lower hazard level. 3.2 The positive pressure enclosure and its connecting pipes must be able to withstand 1.5 times the maximum internal positive pressure during normal operation of the electrical equipment, but at least is 2×10'Pa. If positive pressure may cause dangerous deformation of the shell, pipes or connecting parts, appropriate safety devices should be installed. 3.3 The positive pressure shell and its connecting pipes must be able to withstand the requirements of Article 21.1 of GB3836.1. Impact test. 3.4 The internal shape of the positive pressure ventilation enclosure and its connecting ducts should ensure smooth air flow and avoid dead corners that may cause gas retention. 3.5 The positive pressure ventilation enclosure must have one or several inlets connected to the air inlet and outlet ducts. , exhaust port. 3.6 The positive pressure compensation housing must have one or several air inlets and one or several exhaust ports that can be properly sealed after ventilation. The positive pressure housing and its connecting pipes must be non-combustible or flame-retardant. Made of non-toxic materials, and should be adequately equipped with specified protective gases and hazardous gases in the operating environment 3.7
National Bureau of Standards Approved on 1987-06-18
1988-03-01 Implementation
corrosion resistance. GB38.36.5-87
3.8 Quick-opening doors or covers must be equipped with an interlocking device to ensure that the door or cover cannot be opened before the power is turned off; after the door or cover is opened, the power cannot be turned on.
3.9 Doors or covers fastened with bolts do not need to be equipped with interlocking devices, but a warning sign must be placed on an obvious part of the shell with the words "Open the cover after cutting off the power supply!"
3.10 Built-in electric heater Or the shell of the capacitor, measures must be taken to delay opening the quick-open door or cover after cutting off the power supply in accordance with the provisions of Chapter 5 of GB3836.1.
4Maximum surface temperature
The maximum allowable surface temperature of the positive pressure shell and its connecting pipes must comply with the requirements of Chapter 4 of GB3836.1. When the protective gas is interrupted and the surface temperature of the components and devices inside the shell may exceed the regulations, measures must be taken (such as making the heating components and devices into encapsulated or airtight structures, taking auxiliary ventilation measures, etc.) to ensure that the heating components and devices are in contact with each other. It is possible to come into contact with explosive mixtures only after isolating the outside world or ensuring that the surface temperature of heating elements and devices is cooled below the specified value. 5 Safety measures
Safety devices (such as protective relays, measuring instruments, meters, etc.) used in electrical equipment, when installed in explosion-risk locations, must adopt the corresponding explosion-proof type according to the requirements of the location. 5.1 Electrical equipment must have safety devices (such as time relays, flow monitors, etc.) to ensure sufficient air exchange, so that the power cannot be connected until the concentration of the explosive mixture in the shell drops below the lower explosion limit. The minimum air exchange volume shall be determined according to the test of 9.3, but shall be at least 5 times the total net volume of the shell and its connecting pipes.
5.2 Electrical equipment must be equipped with automatic devices to ensure that when the positive pressure in the enclosure drops below the specified minimum value during startup or operation, the equipment used in Zone 1 must be able to automatically cut off the power supply; the equipment used in Zone 2 must be able to automatically cut off the power supply. The equipment can send out continuous sound and light alarm signals. 5.3 When the protective gas is interrupted, if there are components or devices (such as heaters, etc.) that still need to be energized inside the shell, other corresponding explosion-proof forms must be adopted to avoid creating a source of danger.
5.4 When thousands of independent shells share a protective gas source, several shells can be grouped together to consider the safety monitoring effect under the most unfavorable conditions of the shell and share a safety device. When the door or cover of an independent enclosure is opened, the public safety device does not need to cut off the power supply of this group of enclosures or send out an alarm signal as long as the following three conditions are met. a. Only after cutting off the power supply can the door or cover of the independent housing be opened; b. The public safety device can continue to monitor the positive pressure in the remaining shells of the group; c. The independent shell can be connected to the power supply only after the independent shell is ventilated according to the provisions of Article 5.1. 6 Positive pressure value
All parts of the positive pressure shell and its connecting pipes that may cause leakage must have a positive pressure value of not less than 50Pa relative to the outside atmosphere. The internal pressure distribution of various structures of positive pressure shells and their connecting pipes is shown in Figures A1 to A4 of Appendix A. Note: The fan and its connecting pipes must not create a source of danger. The basic requirements for the installation of piping systems are listed in Appendix A. 7 Protective gas
The protective gas must be non-flammable, and its chemical properties or the physical and chemical properties of the impurities contained must not affect the safety of electrical equipment and the reliability of normal operation.
Note: ① The protective gas can be used for other purposes, such as cooling electrical equipment. ② When using inert gases that are harmful to the human body, a warning sign should be placed in an obvious place on the casing. 8 Marks
8.1 In addition to the markings specified in Chapter 30 of GB3836.1, the nameplate of electrical equipment must also be marked with the following content: a.
GB3836.5-87
Protection Gas type and minimum positive pressure value when the equipment is running; b. Net internal volume of the equipment;
Note: When the user determines the air exchange volume, the internal volume of the connecting pipe must be included. c. Other instructions for marrying. For example, after cutting off the power supply, you must delay opening the door or cover, etc. 8.2 Electrical equipment must be equipped with prescribed warning signs. 8.3 The location of the pressure measuring point determined by the inspection unit must be clearly shown on the electrical equipment or on the explosion-proof certificate. 9 Test
Electrical equipment can be tested for explosion-proof performance at the manufacturer or at the installation and use site to confirm whether it complies with the provisions of this standard. In addition to the relevant provisions of Chapter 4 of GB3836.1, the testing of electrical equipment must also be conducted with the following supplementary tests. 9.1 Measurement of the protective gas flow rate and positive pressure value of the air inlet. Install a pressure measuring instrument at the location where the lowest positive pressure value may occur inside the shell and where external gas may invade. Connect the protective gas pipeline and regulating instrument. Adjust the air inlet flow and pressure to the design minimum value, and measure the positive pressure value of each pressure measuring point to see if it meets the requirements of Chapter 6. Record the measurement results in the table below. This test must be conducted separately for rotating electrical machines at rest and at rated speed. Inlet protective gas
Flow rate, m/s
Inlet pressure
Pa
Note: ①The error of the instrument used should be considered when measuring pressure. 1
2
Positive pressure value at the measuring point, Pa
3
4
②The measuring point is based on the shell, pipe structure and air flow route determined by analysis. Generally, consideration should be given to installing pressure measuring instruments in the following locations: a. The part where the rotating shaft extends outside the shell;
.b. Near the main rotating part inside the shell: 'c The part where the air flow may change drastically; d. At the inlet and exhaust ports;
c. The location where the user plans to install the pressure measuring instrument. 9.2 Shell strength test
5
When the electrical equipment is not powered on, close all the pressure relief ports of the positive pressure shell, fill it with compressed air to reach the pressure value specified in Article 3.2, and maintain it for 5 minutes. The connecting pipe is qualified if there is no breakage or residual deformation, and there is no extrusion or misalignment of the sealing gasket. 9.3 Determination of minimum air exchange volume
For electrical equipment, close all pressure relief ports of the positive pressure shell and its connecting pipes when the power is off, and set 2 to 3 measuring points in the dead corners where gas may be trapped in the shell. A mixture of hydrogen and air and a mixture of carbon dioxide and air with a concentration of 59% to 61% by volume are filled into the shell successively and tested separately (other detection gases, such as inert gas ammonia, can also be used depending on the specific situation). Open the protective gas supply device and exhaust port, adjust the air inlet pressure and flow to the specified minimum value for ventilation. When the hydrogen or carbon dioxide concentration drops below 1% at all measurement points, record the measurement time t. The air exchange rate is calculated according to the formula:
WQ·tp
where W---minimum air exchange rate, m;
Q——minimum flow rate of protective gas, m/ s; t, measurement time, s.
9.4 Protection device action reliability test
The protection device action reliability is tested according to the following procedures: a.
Electrical equipment cannot be turned on before ventilating; GB3836.5-87| | tt | When the value is below the value, the protection device can reliably send a signal or cut off the power supply.
The test must be carried out 5 times in a row
Temperature measurement
9.5
Under rated operating conditions, the electrical equipment must be supplied with the protective gas with the lowest flow and pressure, and then press GB3861 Temperature measurement is required in Article 24.1.
If it is deemed unnecessary based on analysis of the specific situation, this test can be dispensed with. 9.6 Measurement of the cooling time of heating elements and devices inside the shell after power is cut off. After the electrical equipment is operated according to the requirements of Article 9.5 until the temperature rise stabilizes, cut off the power supply. Without opening the door or cover and continuing to pass the minimum amount of protective gas, use Stopwatch, etc., measure the time it takes for the internal heating elements and devices to cool down to a safe temperature (thermocouples can be used to measure the temperature of the internal heating elements and devices).
9.7 Non-flammability and flame-resistance test
The non-flammability and flame-resistance test shall be carried out in accordance with the current national standards. GB3836.5-87
Appendix A
Protective gas delivery pipeline
(supplement)
Protective gas must be input into the air inlet pipe in non-explosive hazardous locations, using compressed gas The exception is bottled gas. A.11
The ventilator and air inlet duct must be properly designed and installed so that surrounding explosive gases or vapors cannot enter the piping system. A.2 The end exhaust port of the protective gas exhaust pipe should generally be set in a non-explosive hazardous location, with the following exceptions: electrical equipment that does not produce any sparks and hot particles during normal operation, the end of the exhaust pipe The exit can be set in zone 2. a.
b.
If the electrical equipment is equipped with a device that can effectively prevent sparks and hot particles from blowing out (see Figure A1b) and due to the temperature requirements of the built-in heating elements and devices, there is no device to prevent the surrounding air. If the corresponding device quickly penetrates into the shell, the end outlet of the exhaust pipe of Class 1 electrical equipment can be set in an explosion hazardous location; the end outlet of the exhaust pipe of Class II electrical equipment can be set in Zone 1. Examples of static positive pressure distribution in pipes and shells are shown in Figure A1 to Figure A4(a)
2
(b)
positive pressure value
(b)| | tt | Non-explosive hazardous locations (b) - Positive pressure value
Pa
50
o
Positive pressure value
Pa
50H| |tt||0
mbat
External air pressure
External air pressure
GB3836.5-87
Figure A2 Positive pressure without rotating parts in the enclosure Compensation housing 2
Figure A3 Positive pressure value of rotating motor with positive pressure compensation housing and internal fan
External air pressure
P
GB3836.5-87|| tt||Figure A4 Rotating motor waos with positive pressure compensation casing and external fan
Note: In the examples of Figures A2 to A4, a ventilator is used to ensure the positive pressure in the casing. Other methods can also be used to ensure positive pressure within the enclosure. For example: transporting compressed air in cylinders, using air compressors, etc. Therefore, the pressure distribution in the duct before the housing inlet may be different. In the picture: z
Z,
P,
P
P,
P
Ps
1-
2-
3-
5
6
7
-Class II (Factory) Explosion Hazardous Location Zone 1 or| Category (coal mine) explosive hazardous locations; Class II explosive hazardous locations Zone 2 or Class II explosive hazardous locations; non-explosive hazardous locations;
protective gas pressure distribution (depends on the air flow resistance of pipes and assemblies, sometimes depending on for the throttle valve and spark and hot particle arrester);
protective gas pressure distribution (approximately constant); protective gas pressure distribution (depending on the air flow resistance of the assembly, between the dotted lines A and B Influence of the internal fan); protective gas pressure distribution (depending on the air flow resistance of the assembly and affected by the external fan); external air pressure;
a protective gas inlet;
pipe;
Ventilator;
Housing;
A pressure monitor;
Throttle valve (set to maintain positive pressure); Ventilation valve; || tt||A protective gas outlet;
8
9-
Spark or hot particle arrester
Additional notes:
This standard is governed by Proposed by the National Explosion-proof Electrical Equipment Standardization Technical Committee. This standard is drafted by the Nanyang Explosion-proof Electrical Research Institute of the Ministry of Machinery Industry. The main drafters of this standard are Ma Jinggang, Li Xiaoquan, Yang Yongzhen, Ren Jiazhi, and Shi Fusheng. This standard is entrusted to the National Explosion-proof Electrical Equipment Standardization Technical Committee. explain.2. The end outlet of the protective gas exhaust pipe should generally be set in a non-explosive hazardous location, but the following exceptions can be made: For electrical equipment that does not produce any sparks and hot particles during normal operation, the end outlet of the exhaust pipe can be Set in zone 2. a.
b.
If the electrical equipment is equipped with a device that can effectively prevent sparks and hot particles from blowing out (see Figure A1b) and due to the temperature requirements of the built-in heating elements and devices, there is no device to prevent the surrounding air. If the corresponding device quickly penetrates into the shell, the end outlet of the exhaust pipe of Class 1 electrical equipment can be set in an explosion hazardous location; the end outlet of the exhaust pipe of Class II electrical equipment can be set in Zone 1. Examples of static positive pressure distribution in pipes and shells are shown in Figure A1 to Figure A4(a)
2
(b)
positive pressure value
(b)| | tt | Non-explosive hazardous locations (b) - Positive pressure value
Pa
50
o
Positive pressure valuewww.bzxz.net
Pa
50H| |tt||0
mbat
External air pressure
External air pressure
GB3836.5-87
Figure A2 Positive pressure without rotating parts in the enclosure Compensation housing 2
Figure A3 Positive pressure value of a rotating motor with positive pressure compensation housing and internal fan
External air pressure
P
GB3836.5-87|| tt||Figure A4 Rotating motor waos with positive pressure compensation casing and external fan
Note: In the examples of Figures A2 to A4, a ventilator is used to ensure the positive pressure in the casing. Other methods can also be used to ensure positive pressure within the enclosure. For example: transporting compressed air in cylinders, using air compressors, etc. Therefore, the pressure distribution in the duct before the housing inlet may be different. In the picture: z
Z,
P,
P
P,
P
Ps
1-
2-
3-
5
6
7
-Class II (Factory) Explosion Hazardous Location Zone 1 or| Category (coal mine) explosive hazardous locations; Class II explosive hazardous locations Zone 2 or Class II explosive hazardous locations; non-explosive hazardous locations;
protective gas pressure distribution (depends on the air flow resistance of pipes and assemblies, sometimes depending on for the throttle valve and spark and hot particle arrester);
protective gas pressure distribution (approximately constant); protective gas pressure distribution (depending on the air flow resistance of the assembly, between the dotted lines A and B Influence of the internal fan); protective gas pressure distribution (depending on the air flow resistance of the assembly and affected by the external fan); external air pressure;
a protective gas inlet;
pipe;
Ventilator;
Housing;
A pressure monitor;
Throttle valve (set to maintain positive pressure); Ventilation valve; || tt||A protective gas outlet;
8
9-
Spark or hot particle arrester
Additional notes:
This standard is governed by Proposed by the National Explosion-proof Electrical Equipment Standardization Technical Committee. This standard is drafted by the Nanyang Explosion-proof Electrical Research Institute of the Ministry of Machinery Industry. The main drafters of this standard are Ma Jinggang, Li Xiaoquan, Yang Yongzhen, Ren Jiazhi, and Shi Fusheng. This standard is entrusted to the National Explosion-proof Electrical Equipment Standardization Technical Committee. explain.2. The end outlet of the protective gas exhaust pipe should generally be set in a non-explosive hazardous location, but the following exceptions can be made: For electrical equipment that does not produce any sparks and hot particles during normal operation, the end outlet of the exhaust pipe can be Set in zone 2. a.
b.
If the electrical equipment is equipped with a device that can effectively prevent sparks and hot particles from blowing out (see Figure A1b) and due to the temperature requirements of the built-in heating elements and devices, there is no device to prevent the surrounding air. If the corresponding device quickly penetrates into the shell, the end outlet of the exhaust pipe of Class 1 electrical equipment can be set in an explosion hazardous location; the end outlet of the exhaust pipe of Class II electrical equipment can be set in Zone 1. Examples of static positive pressure distribution in pipes and shells are shown in Figure A1 to Figure A4(a)
2
(b)
positive pressure value
(b)| | tt | Non-explosive hazardous locations (b) - Positive pressure value
Pa
50
o
Positive pressure value
Pa
50H| |tt||0
mbat
External air pressure
External air pressure
GB3836.5-87
Figure A2 Positive pressure without rotating parts in the enclosure Compensation housing 2
Figure A3 Positive pressure value of rotating motor with positive pressure compensation housing and internal fan
External air pressure
P
GB3836.5-87|| tt||Figure A4 Rotating motor waos with positive pressure compensation casing and external fan
Note: In the examples of Figures A2 to A4, a ventilator is used to ensure the positive pressure in the casing. Other methods can also be used to ensure positive pressure within the enclosure. For example: transporting compressed air in cylinders, using air compressors, etc. Therefore, the pressure distribution in the duct before the housing inlet may be different. In the picture: z
Z,
P,
P
P,
P
Ps
1-
2-
3-
5
6
7
-Class II (Factory) Explosion Hazardous Location Zone 1 or| Category (coal mine) explosive hazardous locations; Class II explosive hazardous locations Zone 2 or Class II explosive hazardous locations; non-explosive hazardous locations;
protective gas pressure distribution (depends on the air flow resistance of pipes and assemblies, sometimes depending on for the throttle valve and spark and hot particle arrester);
protective gas pressure distribution (approximately constant); protective gas pressure distribution (depending on the air flow resistance of the assembly, between the dotted lines A and B Influence of the internal fan); protective gas pressure distribution (depending on the air flow resistance of the assembly and affected by the external fan); external air pressure;
a protective gas inlet;
pipe;
Ventilator;
Housing;
A pressure monitor;
Throttle valve (set to maintain positive pressure); Breather valve; || tt||A protective gas outlet;
8
9-
Spark or hot particle arrester
Additional notes:
This standard is governed by Proposed by the National Explosion-proof Electrical Equipment Standardization Technical Committee. This standard is drafted by the Nanyang Explosion-proof Electrical Research Institute of the Ministry of Machinery Industry. The main drafters of this standard are Ma Jinggang, Li Xiaoquan, Yang Yongzhen, Ren Jiazhi, and Shi Fusheng. This standard is entrusted to the National Explosion-proof Electrical Equipment Standardization Technical Committee. explain.
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