Analysis on the misunderstanding of the hottest ex

2022-08-13
  • Detail

Misunderstanding analysis of explosion-proof electrical equipment

many people believe that the reason why explosion-proof electrical equipment can be explosion-proof is that its shell can prevent explosive gases from entering its interior, and its sealing performance must be very good, which can prevent rainwater from entering. There should be no problem when it is installed outdoors and used in the open air. In fact, this is a confusion between the explosion-proof form of explosion-proof electrical equipment and the enclosure protection level

explosion proof electrical equipment is divided into different explosion-proof forms according to their explosion-proof principles. Explosion proof electrical equipment is an electrical equipment with a shell that can withstand the explosion pressure of the internal explosive gas mixture and prevent the internal explosion from spreading outward. If conditions permit, the explosive mixture around the shell. Obviously, its explosion-proof performance has nothing to do with the protection grade of the housing. The national standard has no special requirements for the protection grade of the housing, as long as it meets the protection grade requirements of the housing of motors and low-voltage electrical appliances, but it has strict regulations on the material and mechanical strength of the housing. Increased safety explosion-proof electrical equipment is an electrical equipment that will not produce arcs, sparks or high temperatures that may ignite explosive mixtures under normal operating conditions. Measures are taken to improve safety to avoid these phenomena under normal and recognized overload conditions. The intrinsically safe explosion-proof electrical equipment (mostly seen in small weak current equipment) is an electrical equipment whose all circuits cannot ignite the specified explosive mixture under the specified fault state. These two kinds of explosion-proof electrical equipment either do not produce sparks and high temperatures, or the sparks and thermal effects are not enough to ignite the explosive mixture. Obviously, their explosion-proof performance is also irrelevant to the enclosure protection grade. Therefore, the national standard has cultivated a batch of professional talents, and there are no special requirements for the enclosure protection grade

it can be seen that the vast majority of explosion-proof electrical equipment can not prevent gas or water from entering its interior, so these explosion-proof electrical equipment cannot be directly installed in outdoor places, nor can their shells be washed with water. In fact, the waterproof performance of the equipment is completely determined by its enclosure protection grade. Generally, the protection grade of the enclosure of outdoor electrical equipment that can prevent rainwater should reach ipx5 (that is, it can withstand water spray from all directions without water entering). Therefore, when purchasing explosion-proof electrical equipment, it is necessary to put forward the requirements of the enclosure protection grade at the same time. In addition, it should be noted that the explosion-proof electrical equipment used outdoors should be corrosion-resistant

Myth 2: gas explosion-proof electrical equipment can be used in dust explosion hazardous places

at present, many people still lack sufficient understanding of dust explosion-proof and dust explosion-proof electrical equipment. In practical application, gas explosion-proof electrical equipment is used in both gas explosion hazardous places and dust explosion hazardous places. In fact, this is wrong, because it can be seen from the explosion-proof principle of all explosion-proof electrical equipment that the enclosure protection grade of most gas explosion-proof electrical equipment is low, and its signal output is the number of rectangular wave pulses in each sinusoidal cycle (the number of pulses depends on the multiple ratio) depends on the dust explosion-proof electrical equipment. If the gas explosion-proof electrical equipment is used in the dust explosion-proof dangerous places, the dust will enter the equipment and accumulate, This will hinder the safe operation of explosion-proof electrical equipment. Of course, the enclosure protection grade of gas explosion-proof electrical equipment can also be improved and used in places with dust explosion hazards, but this is extremely uneconomical, because the explosion-proof and safety enhancement functions used for gas explosion-proof are wasted

conversely, can dust explosion-proof electrical equipment be used in gas explosion hazardous areas? The answer is No. Because the dust explosion-proof electrical equipment only has a high degree of protection of the shell, it cannot prevent explosive gases from entering its shell, and there are no explosion-proof measures such as explosion-proof and safety increase, so these two kinds of explosion-proof electrical equipment must not be replaced

myth 3: the electrical equipment in the crushing place of agricultural products does not need explosion-proof

this is a common misunderstanding in the vast rural areas at present. In fact, the dust with explosive danger can be divided into the following four types: explosive dust, combustible conductive dust, combustible non-conductive dust and combustible fiber. Agricultural product dust belongs to combustible non-conductive dust. Taking barley flour as an example, its explosion risk indicators are actually equivalent to the red phosphorus powder in the metal. Therefore, the explosion-proof problem of agricultural products crushing and processing sites "must be paid enough attention in the beverage and food packaging materials industry, and explosion-proof electrical equipment must be selected

Copyright © 2011 JIN SHI