The basic form of explosion protection

Basic explosion-proof type

(1) Flameproof type “d” Explosion-proof type explosion-proof type is to completely enclose the parts of the equipment that may ignite the explosive gas mixture in a shell whose outer shell can withstand any joint or structural gap through the shell and penetrate into the interior of the shell. The sexual mixture detonates inside without damage and does not ignite the external explosive atmosphere formed by one or more gases or vapours (see standard). Place parts that may generate sparks, arcs, and dangerous temperatures into a flameproof enclosure that isolates the interior of the equipment from the surrounding environment. There is a gap in the flameproof enclosure. Due to the respiration of the electrical equipment and the gas permeation, an explosive gas mixture may exist inside. When the explosion occurs, the enclosure can withstand the explosion pressure generated without damage, and at the same time, the gap of the shell structure can cool the flame and lower the flame. The speed of flame propagation or the acceleration of the chain is such that flame or dangerous flame products cannot ignite the external explosive atmosphere through the flameproof gap, thereby achieving the purpose of flameproof. The explosion-proof type “d” is classified into Type I and Type IIA, Type IIB, and Type IIC according to the types of explosive gas atmospheres it is allowed to use. This type of explosion-proof equipment is suitable for use in places 1 and 2.

(2) Increased safety type "e" Increased safety type explosion protection type is a kind of additional measures taken to improve the safety of electrical equipment that will not produce arcs or sparks under normal operating conditions to prevent the occurrence of internal and external components. Explosion-proof type of possibility of danger temperature, arc and spark. It does not include equipment that generates sparks or arcs under normal operating conditions (see

GB standard). In the normal operation of the electrical equipment structure that will not produce sparks, arcs and dangerous temperatures, by taking measures to reduce or control the operating temperature, ensure the reliability of the electrical connection, increase the insulation effect and improve the degree of protection of the enclosure to reduce pollution due to dirt The possibility of entering and the introduction of moisture, etc., to reduce the possibility of causing ignition failure, and improve the safety and reliability of the equipment in the normal operation and the provisions of the fault (for example, the rotor locked rotor). 〖JP〗 This type of equipment is mainly used in hazardous areas in Zone 2 and some types can be used in Zone 1 such as increased safety low voltage asynchronous motors with suitable protection devices, junction boxes, etc.

(3) Intrinsically safe "i" Intrinsically safe explosion-protected versions are those where all electrical circuits within the equipment are produced under standard conditions (including normal operation and specified fault conditions) and any spark or any thermal effect cannot be produced. An intrinsically safe circuit that ignites a prescribed explosive atmosphere. 〖HTH〗“i” grade electrical equipment 〖HT〗 is an intrinsically safe electrical equipment that cannot cause ignition under normal operating conditions and with both a fault and an arbitrary combination of two fault conditions; 〖HTH〗 “ib” grade electrical equipment HT is an intrinsically safe electrical device that does not cause ignition under normal operating conditions and by applying a fault condition (see standard). The intrinsically safe type starts from limiting the energy in the circuit. The potential spark energy is reduced to the ignitable prescribed gas mixture energy by reliable control circuit parameters, and the surface heating temperature of the wire and component is limited to the ignition temperature of the specified gas mixture. under. This explosion-proof type can only be applied to weak electrical equipment. This type of equipment is suitable for Zones 0, 1, 2 (Ex i) or Zone 1 (E x ib).

(4) An explosion-proof version of positive pressure type "p" electrical equipment. It is an electrical device that achieves safety by keeping the pressure of the protective gas inside the device enclosure higher than the surrounding explosive atmosphere (see standard). Positive pressure equipment protection can use different methods. One approach is to protect the static positive pressure inside the system, and the other is to maintain a constant flow of air or inert gas to limit the entry of the flammable mixture into the interior of the enclosure. Both methods require flushing of the enclosure with protective gas prior to start-up of the device to remove flammable gases in the enclosure when the device is in a non-positive pressure state to prevent the formation of a flammable mixture within the enclosure. The main point of these methods is to monitor the system and conduct regular ventilation to ensure the reliability of the system. Such equipment can be used in hazardous areas in Zone 1 or Zone 2 according to the protection method.

(4) Oil-immersed type “o” The oil-immersed type is an explosion-proof type in which the entire device or parts of equipment are immersed in oil (protective fluid) so that it cannot ignite an explosive atmosphere above or outside the enclosure (see standard). This is an old explosion-proof technology method that is mainly used for switchgear. The arc and sparks formed are immersed in oil. This type of equipment is suitable for hazardous areas in Zone 1 or Zone 2. (6) The sand-filled “q” sand-filled explosion-proof type is a kind of powder material filled with sand or other specified characteristics in the shell so that the arc or high temperature generated in the shell cannot ignite the surrounding explosive gas under the specified use conditions. Environmental protection of electrical equipment (see standard). This explosion-proof version fixes and completely buries the conductive parts of the explosive gas atmosphere and completely embeds them in the sand-filled material, thereby preventing the propagation of sparks, arcs and dangerous temperatures, making it impossible to ignite the external explosive atmosphere. It is typically used for components and heavy-duty traction battery packs in Ex "e" or Ex "n" devices. This type of equipment is suitable for hazardous areas in Zone 1 or Zone 2.

(7) "n" Type Explosion-Proof Electrical Equipment This type of electrical equipment is not capable of igniting the surrounding explosive atmosphere during normal operation and is unlikely to cause ignition failure (see standard). When the n” type electrical equipment is in normal operation, it means that the equipment is electrically and mechanically conforming to the design specifications and used within the range specified by the manufacturer, and it is impossible to generate sparks, arcs, and dangerous temperatures. This type of electrical equipment is only applicable to Zone 2 hazards. place.

(8) Encapsulated type "m" Enclosed type explosion-proof type is an electrical component that may cause sparks, arcs, or dangerous temperature parts that can cause explosion of an explosive mixture. It is encapsulated in a potting compound (composite) so that it cannot ignite. Surrounding explosive mixture (

See standard). The use of encapsulation measures prevents short circuiting of electrical components, solidification of electrical insulation, avoidance of sparks on the circuit, generation of ignition sources such as arcs and hazardous temperatures, prevention of intrusion of explosive mixtures, and control of surface temperatures under normal and fault conditions. This type of equipment is suitable for hazardous areas in Zones 1 and 2.

(9) Hermetically sealed "h" This type of explosion-proof equipment uses an airtight enclosure. That is, the explosive gas mixture in the environment cannot enter the inside of the device housing. The airtight enclosure is sealed by melting, squeezing or gluing. Most of the enclosures are non-detachable to ensure permanent airtightness (see standard). This explosion-proof measure belongs to the category of "n" explosion protection measures and has been replaced by -2003.

(10) Special-type explosion-proof electrical equipment "s" refers to explosion-proof types not included in national standards. This type may be provisionally prescribed by the competent authority, and may be approved by the designated explosion-proof inspection agency as electrical equipment capable of explosion-proof performance. Such equipment is developed based on actual use and can be applied to corresponding hazardous locations.

(11) Combustion dust electrical equipment dust explosion-proof electrical equipment is to limit the maximum surface temperature of the enclosure and the use of "dust-tight" or "dust-proof" enclosures to limit the entry of dust to prevent ignition of flammable dust (see standard). This kind of equipment will install live parts in a protective enclosure, which limits the entry of dust and isolates the ignition source from the dust to prevent explosions. According to the difference in the dust-proof structure of the device, the device is divided into Type A device or Type B device. According to the dust level of the device shell, the device is divided into 20, 21 and 22 levels, such as DIP A20, DIP A21, DIP B20 and DIP B21. This type of equipment is suitable for dust hazardous locations in areas 20, 21 or 22 according to grade. It may be easy to see in normal practical use that many explosion-proof electrical products use a variety of explosion protection methods in one product. For example, lighting devices may employ increased safety protection (housing and terminal box), flameproof protection (switch), and encapsulation type protection (ballast). This will enable manufacturers to use the most suitable composite explosion protection method. One thing to note is that the order of the explosion protection methods listed on the product nameplate will often tell the user the structure of the product. If a product is identified as Ex de, it is most likely to be flameproof with increased safety components. . Another product identified as Ex ed is most likely not a flameproof enclosure (such as stainless steel or reinforced polyester glass) with a flameproof switch or component mounted therein. Both products may be suitable for use in Zone 1, but they use different explosion protection measures to achieve the same purpose. Users can choose to provide reliable performance in terms of cost, performance, and security based on their actual needs and information they understand.