(1) Flameproof type "d"
The explosion-proof explosion-proof type is to enclose all the parts of the equipment that may ignite explosive gas mixtures in a shell, and its shell can withstand any joint surface or structural gap of the shell, and the flammable mixture that penetrates into the shell will explode inside without damage. And it will not cause the ignition of an explosive atmosphere formed by one or more gases or vapors (see GB 3836 2 standard). All components that may generate sparks, arcs and dangerous temperatures are placed in the flameproof enclosure, which separates the internal space of the equipment from the surrounding environment. There is a gap in the flameproof enclosure. Due to the respiration and gas penetration of electrical equipment, there may be an explosive gas mixture inside. When it explodes, the enclosure can withstand the explosion pressure without damage. At the same time, the structural gap of the enclosure can cool the flame and reduce The speed of flame propagation or the termination of the acceleration chain, so that the flame or dangerous flame products cannot pass through the explosion-proof gap to ignite the external explosive environment, so as to achieve the purpose of explosion-proof.
Flameproof type "d" is divided into Class I and Class IIA, IIB, and IIC according to the types of explosive gas atmospheres that are allowed to be used.
This explosion-proof type equipment is suitable for areas 1 and 2.
(2) Increased safety "e"
The increased safety explosion-proof type is a kind of electrical equipment that does not generate arcs and sparks under normal operating conditions to take some additional measures to improve its safety and prevent the possibility of dangerous temperatures, arcs and sparks that may occur in its internal and external components explosion-proof type. It does not include equipment that generates sparks or arcs under normal operating conditions (see GB 38363 standard). On the structure of electrical equipment that does not generate sparks, arcs and dangerous temperatures during normal operation, measures are taken to reduce or control the operating temperature, ensure the reliability of electrical connections, increase the insulation effect, and improve the protection level of the shell to reduce pollution caused by dirt Possibility and moisture ingress and other measures to reduce the possibility of ignition failure and improve the safety and reliability of equipment under normal operation and specified failure conditions (such as: motor rotor stall). This type of equipment is mainly used in hazardous places in Zone 2, and some types can be used in Zone 1, such as increased safety low-voltage asynchronous motors and junction boxes with suitable protective devices.
(3) Intrinsically safe type "i"
Intrinsically safe explosion-proof type is that all circuits inside the equipment are intrinsically safe under the conditions specified in the standard (including normal operation and specified fault conditions), and any electric spark or any thermal effect generated cannot ignite the specified explosive gas atmosphere. circuit. 〖HTH〗"iɑ" level electrical equipment〖HT〗is an intrinsically safe electrical equipment that cannot cause ignition under normal operation, one fault or any combination of two fault conditions; 〖HTH〗"ib" level electrical equipment〖 HT〗is an intrinsically safe electrical equipment that cannot cause ignition under normal operation and a fault condition (see GB 38 364 standard).
Intrinsically safe type starts with limiting the energy in the circuit, and reduces the potential spark energy to below the ignitable gas mixture energy through reliable control circuit parameters, and the heating temperature of the wire and component surface is limited to the ignition temperature of the specified gas mixture. Down.
This explosion-proof type can only be applied to weak current equipment, and this type of equipment is suitable for Zone 0, 1, 2 (Exiɑ) or Zone 1, 2 (Exib).
(4) Positive pressure type "p"
An explosion-proof type of electrical equipment. It is an electrical equipment that achieves safety by keeping the pressure of the protective gas inside the equipment enclosure higher than the pressure of the surrounding explosive environment (see GB 38365 standard).
Types of protection for positive pressure equipment can utilize different methods. One method is to maintain a static positive pressure inside the system, while another method is to maintain a continuous flow of air or inert gas to limit the entry of flammable mixtures into the interior of the enclosure. Both methods need to flush the shell with protective gas before starting the equipment, to take away the flammable gas entering the shell when the equipment is not under positive pressure, and prevent the formation of flammable mixture in the shell. The point of these methods is to monitor the system and perform regular ventilation to ensure the reliability of the system.
This type of equipment can be used in Zone 1 or Zone 2 hazardous locations according to the protection method.
Basic explosion-proof type of explosion-proof motor
(5) Oil-immersed type "o"
The oil-immersed explosion-proof type is to immerse the entire equipment or equipment parts in oil (protective liquid), so that it cannot ignite the explosive gas environment above the oil surface or outside the shell (see GB 38366 standard).
This is an old explosion-proof technology method mainly used for switchgear. The formed arc, spark is immersed under the oil. This type of equipment is suitable for use in Zone 1 or Zone 2 hazardous locations.
(6) Sand-filled type "q"
The sand-filled explosion-proof type is a kind of electrical equipment protection type that fills the shell with sand grains or other powder materials with specified characteristics, so that under the specified conditions of use, neither the arc nor the high temperature generated in the shell can ignite the surrounding explosive gas environment (see GB 38367 standard). This type of protection secures and completely embeds electrically conductive parts capable of igniting an explosive gas atmosphere in a sand-filled material, thereby preventing the propagation of sparks, arcs and dangerous temperatures, making it impossible to ignite the external explosive gas atmosphere. Normally it is used for components in Ex "e" or Ex "n" equipment and heavy duty traction battery packs.
This type of equipment is suitable for use in Zone 1 or Zone 2 hazardous locations.
(7) "n" type explosion-proof electrical equipment
This type of electrical equipment is not capable of igniting the surrounding explosive gas atmosphere during normal operation, and it is unlikely that a fault causing ignition will occur (see
See GB 38368 standard). When "n" type electrical equipment is in normal operation, it means that the equipment meets the design specifications electrically and mechanically and is 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 suitable for hazardous locations in Zone 2.
(8) Encapsulation type "ｍ"
The potting type explosion-proof type is to cast the electrical components that may cause sparks, arcs or dangerous temperature parts that may cause the explosion of explosive mixtures.
In the potting agent (composite), it cannot ignite the surrounding explosive mixture (see GB 38369 standard). 
Pouring measures are used to prevent short circuit of electrical components, solidify electrical insulation, and avoid ignition of sparks on the circuit, arcs and dangerous temperatures.
source generation, prevents the intrusion of explosive mixtures, and controls surface temperatures under normal and fault conditions.
This type of equipment is suitable for hazardous locations in Zones 1 and 2.
(9) Gas-tight type "h"
This type of explosion-proof equipment adopts an airtight enclosure. That is, the explosive gas mixture in the environment cannot enter the interior of the equipment casing. The airtight casing is sealed by melting, extruding or gluing, and most of these casings are not removable to ensure permanent airtightness (see GB 383611 standard).
The explosion-proof measures belong to the category of "n" type explosion-proof measures, and GB 383611 has been replaced by GB 38368-2003.
(10) Special explosion-proof electrical equipment "s"
Refers to the explosion-proof type not included in the national standard, which can be provisionally stipulated by the competent department and approved by the designated explosion-proof inspection unit to be able to have explosion-proof electrical equipment.
This type of equipment is developed according to actual use and can be applied to corresponding dangerous places.
(11) Electric equipment for combustible dust environment
Dust explosion-proof electrical equipment restricts the maximum surface temperature of the enclosure and uses "dust-tight" or "dust-proof" enclosures to limit the entry of dust to prevent ignition of combustible dust (see GB 124761 standard).
This type of equipment installs live parts in an enclosure with a certain degree of protection, thereby limiting the entry of dust and isolating the ignition source from the dust to prevent explosions. The equipment is divided into A-type equipment or B-type equipment according to the difference in the dust-proof structure of the shell. The equipment is divided into 20, 21 and 22 according to the dustproof level of the equipment casing, such as DIP A20, DIP A21, DIP B20 and DIP B21.
This type of equipment is suitable for dust hazardous locations in Zone 20, 21 or 22 according to the grade.
In normal practical use, it may be easy to see that many explosion-proof electrical products adopt multiple explosion-proof protection methods in one product. For example, lighting installations may have increased safety protection (enclosures and terminal boxes), flameproof protection (switches) and potting protection (ballasts). This enables manufacturers to adopt the most suitable method of composite explosion protection. One thing to note is that the order of the explosion-proof methods listed on the product nameplate will often tell the user the structure of the product. If a product is marked as Ex de, it is likely to be flameproof with increased safety components. . Another product marked as Ex ed is most likely not a flameproof enclosure (such as stainless steel or reinforced polyester glass), but has a flameproof switch or components installed in it. Both products may be suitable for zone 1, but they use different explosion protection measures to achieve the same purpose. Users can choose the explosion-proof products that can provide the best balance in cost, performance and safety according to their actual needs and information.