With the extensive installation of explosion-proof electrical equipment for hazardous materials explosion hazardous locations, the relevant knowledge should also follow up. Explosion-proof electrical appliances are mainly explosion-proof electric air-conditioning, explosion-proof switch electrical appliances, explosion-proof distribution boxes, explosion-proof instruments, explosion-proof complete sets of equipment and electrical accessories.
With the extensive installation of explosion-proof electrical equipment for hazardous materials explosion hazardous locations, the relevant knowledge should also follow up. Explosion-proof electrical appliances are mainly explosion-proof electric air-conditioning, explosion-proof switch electrical appliances, explosion-proof distribution boxes, explosion-proof instruments, explosion-proof complete sets of equipment and electrical accessories. During the use of these devices, due to mechanical wear or material aging, or affected by the use of the environment, or due to equipment inspection, maintenance, repair work errors and other reasons, so that the explosion-proof electrical equipment explosion performance is reduced or even lost, it will cause the formation of ignition sources Explosion or fire accident. Therefore, in the inspection, maintenance and repair work of explosion-proof electrical equipment, how to evaluate the safety and usability of the old explosion-proof electrical equipment is an urgent problem to be solved.
Operational and environmental conditions affect the safety of in-use explosion-proof electrical equipment
Parts 1, 2, 3, 4, 5, 6, 7, 8 and 9 of CB3836 “Electrical Equipment for Explosive Gas Environmentsâ€, for the structure, design, manufacture and inspection of explosion-proof electrical equipment of different explosion-proof types Specific regulations. The explosion-proof products manufactured by the manufacturer must meet the requirements of the standard, and must be subjected to explosion-proof inspections by a nationally authorized explosion-proof inspection agency, and production and sales must be allowed after obtaining the explosion-proof certification. The bulk explosion-proof products manufactured by the manufacturer must pass the specified factory inspection and be allowed to leave the factory after passing the inspection. Therefore, in general, the explosion-proof safety performance of new explosion-proof electrical products fully meets the requirements of the standards. However, explosion-proof air conditioning products are affected by working conditions and environmental conditions during use, and are subject to varying degrees of wear and tear. Some damages have an adverse effect on the performance of explosion-proof air-conditioning products; some damage will also reduce the explosion-proof electrical products. Explosion-proof safety. For example, the switch electrical component contacts installed in an explosion-proof flameproof distribution box will have poor contact due to mechanical wear, electrical corrosion, or chemical corrosion, which will affect the use performance of the distribution box; The joint surface is corroded for a long time and rust occurs, so that the flameproof performance is reduced or even lost.
The adverse effects of operating conditions and environmental conditions on explosion-proof electrical equipment are:
Poor operating conditions
Explosion-proof electrical equipment is subjected to strong vibration or impact during operation, which can affect the mechanical structure and strength of small electrical equipment, and can also cause loose electrical connections. Frequent start-up, reverse braking, and overload of the motor will affect the winding temperature of the motor. And the surface temperature affects the safety and service life of the equipment. Increased safety electrical equipment is susceptible to adverse operating conditions.
Wet environment
Explosion-proof electrical equipment is operated or stored in a humid environment for a long period of time, which will affect the insulation of electrical equipment, making it easy for electrical equipment to reduce the insulation resistance, cause electrical breakdown or leakage, and destroy the explosion-proof safety of increased safety type and non-spark type equipment. Sexuality can also adversely affect the operational safety of flameproof or other explosion-proof electrical installations. In addition, moisture in the environment will cause flameproof welding of the flameproof equipment and cause corrosion, which will have an adverse effect on the safety of explosion protection.
Corrosion environment
The corrosive environment has a great influence on the explosion-proof electrical equipment. Severe corrosion will cause corrosion of the electrical equipment housing and the fasteners and flameproof joints, destroy the flameproof security of the flameproof housing, and also make other explosion-proof electrical The degree of protection of the device housing is reduced. In addition, corrosive environments can also have an adverse effect on the insulation of electrical equipment, and can also erode exposed conductors, making them poorly contacted and creating sparks.
Ambient temperature
Ambient temperature in excess of 40°C will affect the winding temperature and surface temperature of electrical equipment, because normally the allowable ambient temperature range of explosion-proof electrical equipment is -20°C to +40°C, and the ambient temperature exceeds +40°C, which will cause the temperature of electrical equipment. Raise, affect explosion-proof safety. In addition, long-term operation of electrical equipment at high temperatures can affect the life of electrical insulation materials. If the electrical equipment has a plastic housing, high temperatures will accelerate the aging of the plastic, affecting the operational safety and explosion-proof safety of the equipment.
Other adverse conditions
Sunlight, rain, snow, dust, lightning and other conditions will have adverse effects on explosion-proof electrical equipment. Sunlight can accelerate the photo-aging of insulating materials and plastic shells; rain, snow, and dust can reduce the leakage resistance of the insulating parts, and the dust can also affect the lubrication between relative moving parts (for example, bearings) of the equipment and cause friction. High temperature; Lightning produces an inductive surge voltage on the grid, causing damage to the insulation of electrical equipment. Safety Inspection of Explosion-Proof Electrical Equipment In order to ensure explosion-proof safety and operational safety of explosion-proof electrical equipment, regular and daily inspections and maintenance of in-use explosion-proof electrical equipment and electrical installations should be performed. "Electrical Safety Regulations for Explosive Hazardous Locations" (Trial) and IEC60079-17:2002 "Electrical Equipment for Explosive Gas Environments Part 17: Inspection and Maintenance of Electrical Installations in Hazardous Locations (Excluding Coal Mines)" Operation of Explosion-Proof Electrical Equipment and Electrical Installations And maintenance has been specified in terms of explosion-proof safety.
The inspection level is divided into the following methods and contents:
Visual inspection - the inspection of the apparent defect with the naked eye without the use of inspection equipment or tools, ie routine inspections.
Careful inspection - including visual inspection and inspection using inspection equipment. For example, using a stepladder (necessary place) and/or tool can identify a significant defect inspection. This type of inspection is a professional inspection and should generally be conducted on a regular basis.
One-by-one inspections - including careful inspections and inspections where the apparent defect can only be identified by opening the housing and/or (if necessary) using tools and testing equipment. This inspection is an inspection during the overhaul of equipment.
The inspection type is divided according to the inspection implementation time:
Initial inspection—checks of all electrical equipment, systems, and devices before they are put into operation. It is generally performed in conjunction with the installation acceptance of engineering projects or equipment.
Regular inspections - Routine inspections of all electrical equipment, systems, and devices. Can be carefully checked or checked item by item. Regular inspections are divided into professional inspections and overhaul inspections according to the purpose and contents of inspections. Sampling inspections of some electrical equipment, systems, and devices. The sampling inspection may be a visual inspection, a careful inspection or an item-by-item inspection. The specifications and composition of all sampling samples shall be determined according to the purpose of the inspection. The effects of environmental conditions, vibrations, and inherent defects in the design can be monitored through sampling inspections.
Continuous supervision - Regular maintenance, inspection, maintenance, monitoring and maintenance of electrical equipment by experienced and skilled technicians to keep the explosion-proof performance of the equipment in good condition. According to the characteristics of explosion-proof electrical equipment, reference is made to the inspection item list in IEC 60079-17. The inspection items related to the explosion-proof structure and explosion-proof safety of the explosion-proof, increased-safety, and non-sparking electrical equipment related to the equipment itself are listed in Table 1.
Safety evaluation of explosion-proof electrical equipment
The purpose of inspection of explosion-proof electrical equipment is to evaluate the current status of the equipment, to maintain the equipment in a normal state, and to repair or replace equipment that has failed. On the other hand, through daily inspections or professional inspections, it is possible to detect the precursors of equipment failures through the changes in equipment operating status and take relevant measures in a timely manner to avoid the losses caused by equipment failures. In order to evaluate the results of the examination, the basis for evaluation and judgment should be clearly defined. In order to correctly evaluate the safety of the explosion-proof electrical equipment in use, it is necessary to understand the safety level of the new explosion-proof electrical equipment.
New explosion-proof electrical equipment safety
According to the conditions of combustion and explosion, the three elements of flammable substances (for example, natural gas, gasoline vapor, etc.), oxidants (for example, oxygen in air), and ignition sources (open flame, arc, spark, or high temperature) are only in time and space at the same time. When they meet, it is possible to explode or burn. The installation and use of explosion-proof electrical equipment in explosion hazardous environments aims to prevent electrical equipment from becoming a source of ignition. Explosion-proof electrical equipment in accordance with explosion-proof measures are divided into intrinsically safe explosion-proof type, increased safety and other different types. Taking the explosion-proof type as an example, it is to make a sturdy enclosure for electrical equipment, able to withstand the explosion pressure caused by the explosion inside the enclosure without damage; the gap of all joints of the enclosure is less than the maximum experimental safety clearance of the corresponding flammable gas, if flammable When the gas enters the housing and is ignited by the spark, the explosion flame is confined within the housing and cannot ignite the explosive mixture in the external environment of the housing, thereby ensuring the safety of the environment. The shell is a flameproof shell, and the electrical equipment with a flameproof shell is a flameproof electrical equipment.
Explosion-proof electrical equipment is installed and installed in a dangerous explosion environment. Its explosion-proof safety is directly related to production safety. Therefore, safety assessment of explosion-proof electrical equipment in use in the environment should strictly comply with relevant standards and regulations. In the assessment of specific equipment, it is necessary to consider not only the condition of the equipment itself, but also the conditions of the environment, such as the division of hazardous locations and other conditions of the environment, to achieve safety and economy under the premise of safety. Unite.
Explosion-proof electrical appliances must not be disassembled; when dismantling and repairing, the explosion-proof surface of the parts cannot be used as the fulcrum of the tamping bar, and it is even not allowed to knock or hit the explosion-proof surface.
When removing the explosion-proof electrical appliances, remove the windshield and fan, and then use the casing wrench to remove the bolts of the end cap and the bearing cover. Then, use a log or copper rod to strike the shaft in the axial direction to separate the end cover from the machine base. Finally remove the rotor. Remove the parts, the explosion-proof surface should be placed upside down, and covered with rubber or cloth pads, fastening bolts, spring pads and other care not to be lost.
When impregnating and assembling, the insulating paint or dirt attached to the explosion-proof surface shall be cleaned, and no hard objects such as iron pieces may be used for scratching. However, it is possible to use whetstone to grind uneven places. If the explosion-proof surface is damaged, you must use tin-lead solder HISnPb58-2 concentration of hydrochloric acid (for steel parts) or tin-58 to 60% tin-zinc solder, flux 30% ammonium chloride, zinc chloride 70%, add water 100 ~150% of the mixed solution (for cast iron parts) is to be repaired, the bond between the solder and the part must be firm, and the raised part must be smoothed to achieve the specified finish. In order to prevent the explosion-proof surface from rusting, apply oil or replacement rust-proof oil to the explosion-proof surface. Explosion-proof electrical appliances daily maintenance and overhaul precautions Explosion-proof electrical appliances must not be disassembled; When dismantling and overhauling, the explosion-proof surface of the parts cannot be used as the fulcrum of the crowbar, and it is not allowed to knock or hit the explosion-proof surface.
When removing the explosion-proof electrical appliances, remove the windshield and fan, and then use the casing wrench to remove the bolts of the end cap and the bearing cover. Then, use a log or copper rod to strike the shaft in the axial direction to separate the end cover from the machine base. Finally remove the rotor. Remove the parts, the explosion-proof surface should be placed upside down, and covered with rubber or cloth pads, fastening bolts, spring pads and other care not to be lost.
When impregnating and assembling, the insulating paint or dirt attached to the explosion-proof surface shall be cleaned, and no hard objects such as iron pieces may be used for scratching. However, it is possible to use whetstone to grind uneven places.
If the explosion-proof surface is damaged, you must use tin-lead solder HISnPb58-2 concentration of hydrochloric acid (for steel parts) or tin-58 to 60% tin-zinc solder, flux 30% ammonium chloride, zinc chloride 70%, add water 100 ~150% of the mixed solution (for cast iron parts) is to be repaired, the bond between the solder and the part must be firm, and the raised part must be smoothed to achieve the specified finish.
In order to prevent explosion-proof electrical explosion-proof surface rust, should be painted on the explosion-proof surface oil or replacement anti-rust oil.
With the extensive installation of explosion-proof electrical equipment for hazardous materials explosion hazardous locations, the relevant knowledge should also follow up. Explosion-proof electrical appliances are mainly explosion-proof electric air-conditioning, explosion-proof switch electrical appliances, explosion-proof distribution boxes, explosion-proof instruments, explosion-proof complete sets of equipment and electrical accessories. During the use of these devices, due to mechanical wear or material aging, or affected by the use of the environment, or due to equipment inspection, maintenance, repair work errors and other reasons, so that the explosion-proof electrical equipment explosion performance is reduced or even lost, it will cause the formation of ignition sources Explosion or fire accident. Therefore, in the inspection, maintenance and repair work of explosion-proof electrical equipment, how to evaluate the safety and usability of the old explosion-proof electrical equipment is an urgent problem to be solved.
Operational and environmental conditions affect the safety of in-use explosion-proof electrical equipment
Parts 1, 2, 3, 4, 5, 6, 7, 8 and 9 of CB3836 “Electrical Equipment for Explosive Gas Environmentsâ€, for the structure, design, manufacture and inspection of explosion-proof electrical equipment of different explosion-proof types Specific regulations. The explosion-proof products manufactured by the manufacturer must meet the requirements of the standard, and must be subjected to explosion-proof inspections by a nationally authorized explosion-proof inspection agency, and production and sales must be allowed after obtaining the explosion-proof certification. The bulk explosion-proof products manufactured by the manufacturer must pass the specified factory inspection and be allowed to leave the factory after passing the inspection. Therefore, in general, the explosion-proof safety performance of new explosion-proof electrical products fully meets the requirements of the standards. However, explosion-proof air conditioning products are affected by working conditions and environmental conditions during use, and are subject to varying degrees of wear and tear. Some damages have an adverse effect on the performance of explosion-proof air-conditioning products; some damage will also reduce the explosion-proof electrical products. Explosion-proof safety. For example, the switch electrical component contacts installed in an explosion-proof flameproof distribution box will have poor contact due to mechanical wear, electrical corrosion, or chemical corrosion, which will affect the use performance of the distribution box; The joint surface is corroded for a long time and rust occurs, so that the flameproof performance is reduced or even lost.
The adverse effects of operating conditions and environmental conditions on explosion-proof electrical equipment are:
Poor operating conditions
Explosion-proof electrical equipment is subjected to strong vibration or impact during operation, which can affect the mechanical structure and strength of small electrical equipment, and can also cause loose electrical connections. Frequent start-up, reverse braking, and overload of the motor will affect the winding temperature of the motor. And the surface temperature affects the safety and service life of the equipment. Increased safety electrical equipment is susceptible to adverse operating conditions.
Wet environment
Explosion-proof electrical equipment is operated or stored in a humid environment for a long period of time, which will affect the insulation of electrical equipment, making it easy for electrical equipment to reduce the insulation resistance, cause electrical breakdown or leakage, and destroy the explosion-proof safety of increased safety type and non-spark type equipment. Sexuality can also adversely affect the operational safety of flameproof or other explosion-proof electrical installations. In addition, moisture in the environment will cause flameproof welding of the flameproof equipment and cause corrosion, which will have an adverse effect on the safety of explosion protection.
Corrosion environment
The corrosive environment has a great influence on the explosion-proof electrical equipment. Severe corrosion will cause corrosion of the electrical equipment housing and the fasteners and flameproof joints, destroy the flameproof security of the flameproof housing, and also make other explosion-proof electrical The degree of protection of the device housing is reduced. In addition, corrosive environments can also have an adverse effect on the insulation of electrical equipment, and can also erode exposed conductors, making them poorly contacted and creating sparks.
Ambient temperature
Ambient temperature in excess of 40°C will affect the winding temperature and surface temperature of electrical equipment, because normally the allowable ambient temperature range of explosion-proof electrical equipment is -20°C to +40°C, and the ambient temperature exceeds +40°C, which will cause the temperature of electrical equipment. Raise, affect explosion-proof safety. In addition, long-term operation of electrical equipment at high temperatures can affect the life of electrical insulation materials. If the electrical equipment has a plastic housing, high temperatures will accelerate the aging of the plastic, affecting the operational safety and explosion-proof safety of the equipment.
Other adverse conditions
Sunlight, rain, snow, dust, lightning and other conditions will have adverse effects on explosion-proof electrical equipment. Sunlight can accelerate the photo-aging of insulating materials and plastic shells; rain, snow, and dust can reduce the leakage resistance of the insulating parts, and the dust can also affect the lubrication between relative moving parts (for example, bearings) of the equipment and cause friction. High temperature; Lightning produces an inductive surge voltage on the grid, causing damage to the insulation of electrical equipment. Safety Inspection of Explosion-Proof Electrical Equipment In order to ensure explosion-proof safety and operational safety of explosion-proof electrical equipment, regular and daily inspections and maintenance of in-use explosion-proof electrical equipment and electrical installations should be performed. "Electrical Safety Regulations for Explosive Hazardous Locations" (Trial) and IEC60079-17:2002 "Electrical Equipment for Explosive Gas Environments Part 17: Inspection and Maintenance of Electrical Installations in Hazardous Locations (Excluding Coal Mines)" Operation of Explosion-Proof Electrical Equipment and Electrical Installations And maintenance has been specified in terms of explosion-proof safety.
The inspection level is divided into the following methods and contents:
Visual inspection - the inspection of the apparent defect with the naked eye without the use of inspection equipment or tools, ie routine inspections.
Careful inspection - including visual inspection and inspection using inspection equipment. For example, using a stepladder (necessary place) and/or tool can identify a significant defect inspection. This type of inspection is a professional inspection and should generally be conducted on a regular basis.
One-by-one inspections - including careful inspections and inspections where the apparent defect can only be identified by opening the housing and/or (if necessary) using tools and testing equipment. This inspection is an inspection during the overhaul of equipment.
The inspection type is divided according to the inspection implementation time:
Initial inspection—checks of all electrical equipment, systems, and devices before they are put into operation. It is generally performed in conjunction with the installation acceptance of engineering projects or equipment.
Regular inspections - Routine inspections of all electrical equipment, systems, and devices. Can be carefully checked or checked item by item. Regular inspections are divided into professional inspections and overhaul inspections according to the purpose and contents of inspections. Sampling inspections of some electrical equipment, systems, and devices. The sampling inspection may be a visual inspection, a careful inspection or an item-by-item inspection. The specifications and composition of all sampling samples shall be determined according to the purpose of the inspection. The effects of environmental conditions, vibrations, and inherent defects in the design can be monitored through sampling inspections.
Continuous supervision - Regular maintenance, inspection, maintenance, monitoring and maintenance of electrical equipment by experienced and skilled technicians to keep the explosion-proof performance of the equipment in good condition. According to the characteristics of explosion-proof electrical equipment, reference is made to the inspection item list in IEC 60079-17. The inspection items related to the explosion-proof structure and explosion-proof safety of the explosion-proof, increased-safety, and non-sparking electrical equipment related to the equipment itself are listed in Table 1.
Safety evaluation of explosion-proof electrical equipment
The purpose of inspection of explosion-proof electrical equipment is to evaluate the current status of the equipment, to maintain the equipment in a normal state, and to repair or replace equipment that has failed. On the other hand, through daily inspections or professional inspections, it is possible to detect the precursors of equipment failures through the changes in equipment operating status and take relevant measures in a timely manner to avoid the losses caused by equipment failures. In order to evaluate the results of the examination, the basis for evaluation and judgment should be clearly defined. In order to correctly evaluate the safety of the explosion-proof electrical equipment in use, it is necessary to understand the safety level of the new explosion-proof electrical equipment.
New explosion-proof electrical equipment safety
According to the conditions of combustion and explosion, the three elements of flammable substances (for example, natural gas, gasoline vapor, etc.), oxidants (for example, oxygen in air), and ignition sources (open flame, arc, spark, or high temperature) are only in time and space at the same time. When they meet, it is possible to explode or burn. The installation and use of explosion-proof electrical equipment in explosion hazardous environments aims to prevent electrical equipment from becoming a source of ignition. Explosion-proof electrical equipment in accordance with explosion-proof measures are divided into intrinsically safe explosion-proof type, increased safety and other different types. Taking the explosion-proof type as an example, it is to make a sturdy enclosure for electrical equipment, able to withstand the explosion pressure caused by the explosion inside the enclosure without damage; the gap of all joints of the enclosure is less than the maximum experimental safety clearance of the corresponding flammable gas, if flammable When the gas enters the housing and is ignited by the spark, the explosion flame is confined within the housing and cannot ignite the explosive mixture in the external environment of the housing, thereby ensuring the safety of the environment. The shell is a flameproof shell, and the electrical equipment with a flameproof shell is a flameproof electrical equipment.
Explosion-proof electrical equipment is installed and installed in a dangerous explosion environment. Its explosion-proof safety is directly related to production safety. Therefore, safety assessment of explosion-proof electrical equipment in use in the environment should strictly comply with relevant standards and regulations. In the assessment of specific equipment, it is necessary to consider not only the condition of the equipment itself, but also the conditions of the environment, such as the division of hazardous locations and other conditions of the environment, to achieve safety and economy under the premise of safety. Unite.
Explosion-proof electrical appliances must not be disassembled; when dismantling and repairing, the explosion-proof surface of the parts cannot be used as the fulcrum of the tamping bar, and it is even not allowed to knock or hit the explosion-proof surface.
When removing the explosion-proof electrical appliances, remove the windshield and fan, and then use the casing wrench to remove the bolts of the end cap and the bearing cover. Then, use a log or copper rod to strike the shaft in the axial direction to separate the end cover from the machine base. Finally remove the rotor. Remove the parts, the explosion-proof surface should be placed upside down, and covered with rubber or cloth pads, fastening bolts, spring pads and other care not to be lost.
When impregnating and assembling, the insulating paint or dirt attached to the explosion-proof surface shall be cleaned, and no hard objects such as iron pieces may be used for scratching. However, it is possible to use whetstone to grind uneven places. If the explosion-proof surface is damaged, you must use tin-lead solder HISnPb58-2 concentration of hydrochloric acid (for steel parts) or tin-58 to 60% tin-zinc solder, flux 30% ammonium chloride, zinc chloride 70%, add water 100 ~150% of the mixed solution (for cast iron parts) is to be repaired, the bond between the solder and the part must be firm, and the raised part must be smoothed to achieve the specified finish. In order to prevent the explosion-proof surface from rusting, apply oil or replacement rust-proof oil to the explosion-proof surface. Explosion-proof electrical appliances daily maintenance and overhaul precautions Explosion-proof electrical appliances must not be disassembled; When dismantling and overhauling, the explosion-proof surface of the parts cannot be used as the fulcrum of the crowbar, and it is not allowed to knock or hit the explosion-proof surface.
When removing the explosion-proof electrical appliances, remove the windshield and fan, and then use the casing wrench to remove the bolts of the end cap and the bearing cover. Then, use a log or copper rod to strike the shaft in the axial direction to separate the end cover from the machine base. Finally remove the rotor. Remove the parts, the explosion-proof surface should be placed upside down, and covered with rubber or cloth pads, fastening bolts, spring pads and other care not to be lost.
When impregnating and assembling, the insulating paint or dirt attached to the explosion-proof surface shall be cleaned, and no hard objects such as iron pieces may be used for scratching. However, it is possible to use whetstone to grind uneven places.
If the explosion-proof surface is damaged, you must use tin-lead solder HISnPb58-2 concentration of hydrochloric acid (for steel parts) or tin-58 to 60% tin-zinc solder, flux 30% ammonium chloride, zinc chloride 70%, add water 100 ~150% of the mixed solution (for cast iron parts) is to be repaired, the bond between the solder and the part must be firm, and the raised part must be smoothed to achieve the specified finish.
In order to prevent explosion-proof electrical explosion-proof surface rust, should be painted on the explosion-proof surface oil or replacement anti-rust oil.
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