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1. The explosion-proof flameproof enclosure of the mine explosion-proof electrical equipment loses its explosion-proof or explosion-proof property and is called explosion-proof. Explosion-proof equipment that has been detonated, if it explodes inside, it will cause an explosion outside the shell due to the explosion of the casing; or the high-temperature gas ejected from the gap will cause an explosion outside the casing, which is very dangerous. Therefore, any place where explosion-proof electrical equipment must be used in the “Safety Regulations for Coal Mines”, explosion-proof equipment that has been detonated is absolutely prohibited. Common detonation phenomena in coal mines are:

(1) Due to the serious rust of the flameproof joint surface, there are large mechanical damage pits, and the connecting screws are not pressed so that their clearance exceeds the specified value, resulting in detonation.

(2) The casing is deformed due to the collapse of the meteorite, the deformation of the bracket, the serious collision during the handling, and the casing is severely deformed; the screw of the cover, the connecting nozzle and the junction box on the explosion-proof casing is broken, and the screw is damaged. The connecting screws are not uniform, so that the mechanical strength does not meet the specified requirements and the explosion is lost.

(3) Adding components or components in an explosion-proof enclosure without approval, so that some electrical distances are less than the specified value, causing a short circuit between the phases of the outer casing, causing the casing to burn through and detonate.

(4) The connecting cable does not use a qualified seal or an unused seal. The unused cable lugs are not blasted with a qualified baffle and are detonated.

(5) The terminal and the insulating seat tube are burnt, so that the two cavities are connected, and the pressure is superimposed when the two chambers continuously explode, so that the outer casing is blown up and detonated.

(6) The flameproof enclosure is detonated due to weld welding and cracking.

(7) The flameproof joints fixed by bolts may cause the gap to be too large and detonate under the following conditions: 1 loose bolts, spring washers, etc. 2 The spring washer is not flattened or the bolt is loose. 3 bolts or screw holes, not specified.

(8) The cable introduction device of the explosion-proof device has the following conditions: the gap is too large and the explosion occurs: 1 The inner diameter of the sealing ring is larger than the outer diameter of the incoming cable by more than 1 mm. 2 The difference between the inner diameter Do of the inlet nozzle and the outer diameter D of the sealing ring exceeds 1.0 (D≤20mm) or 1.5(20 60mm). 3The thickness of the sealing ring is 0.7 times of the outer diameter of the cable, and the difference between the inner and outer diameters of the sealing ring is 0.3 times of the outer diameter of the cable. 4. The hardness of the sealing ring can not meet the requirements of Shore hardness of 45~55 degrees. The aging loses its elasticity, deterioration and deformation, and the effective size can not reach the sealing effect. 5After the single hole of the sealing ring, insert multiple cables. 6 The sealing ring is not completely wrapped around the cable sheath or the sealing ring is cut over the cable. 7 There are other dressings between the sealing ring and the cable sheath. 8 The seal ring is partially broken. 9 a plurality of sealing rings in the inlet nozzle. 10 Idle inlet or spare high voltage junction box does not have a sealing baffle or a baffle unqualified. ○11 The diameter of the baffle is smaller than the inner diameter of the inlet nozzle by 2mm or more, and the absolute thickness of the baffle is less than 1.82mm. ○12 The baffle is placed inside the sealing ring, and the pressure plate type inlet nozzle or nut inlet nozzle metal ring is placed between the baffle and the sealing ring. ○13 After the inlet nozzle is pressed, there is no margin or the inner edge of the nozzle is not tightly sealed, or the end face of the sealing ring is not in contact with the wall, or the sealing ring can move. ○14 Platen-type inlet nozzle lack of compression bolts or compression bolts are not tightened. ○15 nut-type inlet nozzle is not in place due to disorder, rust, etc. or the finger of one hand can screw the compression nut more than half a turn. ○16 When a compression nut type inlet nozzle is used, a metal washer is missing between the nut and the seal ring. ○17 cable can be easily twitched back and forth at the inlet nozzle (the degree of cable fastening is qualified and its discriminating method: the cable can not be pushed into the wiring compartment by hand in the direction of the cable). ○18 high-voltage armored cable terminal junction box is not filled with insulating rubber, the insulating rubber is not filled above the cable terminal fork, the insulating rubber cracks and can be relatively active.

(9) Explosion-proof plug-in device is detonated when the following conditions are met: 1 The power supply side of the coal drill pin should be connected to the socket, and the load side should be connected to the plug. 2 If the power supply voltage is lower than 1140V, there is no device that prevents sudden unplugging. If the voltage is above 1140V, the plug-in device lacks the electrical interlock device. 3 When the plug is disconnected, the maximum diameter difference W and the minimum effective length L of the flameproof joint surface of the casing are not in conformity with the specified.

2. Maintenance requirements for mining electrical equipment 1) Maintenance of explosion-proof equipment is caused by installation, operation, maintenance quality that does not meet the standard or product quality is not satisfactory. Therefore, quality must be strictly guaranteed to prevent explosion. It is necessary to strictly control the indexes such as the gap, length and roughness of each joint surface of the explosion-proof electrical equipment. The inspector needs to use a steel ruler, a vernier caliper, a feeler gauge and a roughness sample to measure whether the inspection result meets the requirements.

In addition, it is necessary to check whether the shell has permanent deformation or crack; whether the cable lead-out and the introduction device meet the requirements; whether the bolt for fastening is tightened, whether the screw washer is complete, whether the interlock device is complete and whether it meets the integrity standards of the relevant electrical equipment. Relevant regulations.

Careful maintenance of the flameproof enclosure and the flameproof joint is a major part of maintaining the explosion resistance and flameproof performance of the equipment. For this reason, when disassembling the explosion-proof outer cover, it is not possible to strike with a heavy hammer. After opening the outer cover, the explosion-proof joint surface must be properly protected against mechanical damage and pollution; metal joints are not allowed to wipe the joint surface; Rust, a thin layer of Vaseline or anti-rust oil may be applied to the flameproof joint surface, but it is not allowed to be painted.

For coal electric drills and other equipment made of aluminum alloy flameproof enclosures, they must be prevented from colliding with corroded steel during use. This is because the mechanical spark generated by the impact friction between the aluminum alloy and the corroded steel is sufficient to ignite the gas. Causes an explosion of the air mixture. In order to prevent this danger, a surface of the outer casing may be covered with a synthetic resin film having sufficient thickness and durability.

The operation, maintenance and repair of underground explosion-proof electrical equipment must be carried out by trained special maintenance electrician. Explosion-proof electrical equipment must meet the technical requirements of explosion-proof performance. Electrical equipment with damaged explosion-proof performance should be disposed of or replaced immediately, and should not be used continuously. .

2) During the maintenance and use of intrinsically safe electrical equipment, intrinsically safe electrical equipment and its associated electrical equipment shall be inspected regularly and regularly. Mainly check the performance of the components and components used in the intrinsically safe circuit, the insulation of the circuit, the connection and fastening of the external wiring, and whether the grounding is good.