Source: mechanical expert network T | T

Explosion-proof motor is mainly used in coal mine, petroleum and natural gas, petrochemical and chemical industry. In addition, it is widely used in textile, metallurgy, city gas, transportation, grain and oil processing, paper making, medicine and other departments. Explosion-proof motor as the main power equipment, usually used to drive pumps, fans, compressors and other transmission machinery.

With the development of science and technology and production, the places with explosive danger are also increasing. For example, the production of edible oil used to be the traditional squeezing process, after the 1970s, China began to introduce foreign advanced oil leaching process, but this process to use chemical solvents containing hexane, hexane is flammable and explosive substances; Therefore, the oil leaching workshop has become a dangerous place for explosion, which requires the use of explosion-proof motors and other explosion-proof electrical products. For example, in recent years, China's highway development is rapid, a large number of fuel gas stations appear, also provides a new market for explosion-proof motor.

1. According to the principle of the motor, it can be divided into explosion-proof asynchronous motor, explosion-proof synchronous motor and explosion-proof DC motor. 2. According to the place of use, it can be divided into explosion-proof motors used in coal mines and explosion-proof motors used in factories. 3. According to the explosion-proof principle, it can be divided into flameproof motor, increased safety motor, positive pressure motor, spark-free motor and dust explosion-proof motor, etc. 4. According to the host of form a complete set points can be divided into the coal mine conveyor with explosion-proof motor, coal mine hoist with explosion-proof motor, rock loader use explosion-proof motor, coal mine local fan used explosion-proof motor, valve with explosion-proof motor, fan with explosion-proof motor, Marine explosion-proof motor, lifting metallurgical explosion-proof type and hydrogenation device matching with increased safety brushless excitation synchronous motor, etc. In addition, can also be divided according to rated voltage, efficiency and other technical indicators, such as high voltage explosion-proof motor, high efficiency explosion-proof motor, high slip explosion-proof motor and high starting torque explosion-proof motor. This paper introduces the classification of explosion-proof principle.

Product series and characteristics

1. Isolation type motor it uses flameproof housing to separate the electrical parts that may produce sparks, arcs and dangerous temperatures from the surrounding explosive gas mixture. However, the housing is not sealed, and the surrounding explosive gas mixture can enter the motor through the gap between the joint surface of each part of the housing. When contact with spark, arc, dangerous high temperature and other ignition sources in the shell may explode, then the flameproof shell of the motor will not be damaged or deformed, but also the explosive flame or hot gas through the joint surface gap, can not ignite the explosive gas mixture around.

The basic series of low-voltage flameproof motor products widely used in China is YB series flameproof three-phase asynchronous motor, which is the derivative of Y series (IP44) three-phase asynchronous motor. Explosion-proof performance conforms to the provisions of GB3836.1-83 "General Requirements for explosion-proof Electrical Equipment for Explosive Environment" and GB3836.2-83 "Explosion-proof electrical Equipment for Explosive Environment flameproof Electrical Equipment" D "; The motor power range is o.55 -- 200kW, and the corresponding frame size range is the height of the frame center is 80 -- 315nun; The explosion-proof marks are dI, dIIAT4, dIIBT4, respectively, suitable for underground coal mine fixed equipment or factory IIA, IIB class, temperature group for T1-T4 group of combustible gas or steam and air explosive mixture of the place; The main body shell protection grade is IP44, can also be made into IP%4, the junction box protection grade is IP54; Rated frequency is 50Hz, rated voltage is 380, 1660, 1140, 380/660, 660/140V; The insulation grade of the motor is F, but the temperature rise of the stator winding is assessed according to B, which has a large temperature rise margin.

Low voltage flameproof three-phase induction motor derived series of main models are: YB series (dIIcT4)(base center height of 80-315mm), YBSO series (small power, base center height of 63-90mm), YBF series (fan, base center height of 63-160mm), YB -- H series (Marine, base center height of 80-280mm), YB series (medium, The center height of the machine base is 355 -- 450mm), YBK series (for coal mine, the center height of the machine base is 100 -- 315mm), YB -- W, B -- TH, YB -- WTH series (the center height of the machine base is 80 -- 315mm), YBDF -- WF series (for outdoor anti-corrosion and flameproof electric valve, The center height of the frame is 80-315mm) and YBDC series (flameproof capacitor starting single-phase asynchronous motor, the center height of the frame is 71-100mm) and YBZS series of reusable flameproof two-speed three-phase asynchronous motor. In addition, there are YB series of high pressure flameproof three-phase asynchronous motor (the center height of the frame is 355~450mm, 560-710mm).

YB2 series jointly designed by the industry has passed the national identification at the end of 14, and will gradually replace YB series to become the basic series of flameproof three-phase asynchronous motors in China. The YB2 series has a total of 15 frame sizes (center height of the frame is 63, 355nmm), and the power range is o. 12 -- 315kW. Its main characteristics are :(1) the corresponding relationship of power grade, installation size and speed is consistent with DIN42673, and considering the inheritance and interchangeability of YB series and Y2 series, the necessary adjustment is made to be more effective and applicable. (2) The whole series adopts grade F insulation, and the temperature rise is assessed according to grade B. (3) The noise limit is lower than that of YB series, close to the level I noise of YB series, and the vibration limit is similar to that of YB series. (4) The protection level of the shell is improved to IP55. (5) Low noise deep groove ball bearings are selected for the whole series, and oil injection and discharge devices are set for motors with the center height of the frame above 180mm. (6) The motor radiator has two kinds of parallel horizontal distribution and radiation distribution, mainly parallel horizontal distribution. (7) The main performance indexes reach the international advanced level in the early 1990s.

2. Increase safety type motor it is under normal operating conditions will not produce arc, spark or dangerous high temperature motor structure, and then take some mechanical, electrical and thermal protection measures, so as to further avoid the normal or recognized overload conditions of arc, spark or high temperature danger, so as to ensure its explosion-proof safety.

The basic series of low-voltage increasing safety type used in China is YA series increasing safety type three-phase asynchronous motor, which is the derivative of Y series (IP44) three-phase asynchronous motor. Explosion-proof performance conforms to gb3836.1-83 "Explosion-proof electrical Equipment for Explosive Environment general Requirements" and GB3836.3-83 "explosion-proof electrical Equipment for Explosive Environment increased safety type electrical equipment" E "; The power range is o. 55~90kW, and the center height of the corresponding frame is 80-280mm; The explosion-proof marks are eIITl, eIIT2 and eIIT3, respectively, which are suitable for the places with tL-T3 explosive mixture and slightly corrosive medium in the factory. The protection grade of the main body shell is IP54, and the protection grade of the junction box is IP55; Rated frequency is 50Hz, rated voltage is 380V; Motor uses F class insulation.

The main models of low-voltage increasing safety motor derived series are: YASO series low-power increasing safety three-phase asynchronous motor (center height of the frame is 56 -- 90mm), Ya-W, Ya-WFL series outdoor, indoor anti-corrosion increasing safety three-phase asynchronous motor (center height of the frame is 80 -- 280mm).

At present, the industry joint design work of YA2 and series has been completed, and trial production is being organized to replace YA series. YA2 whole series has 15 frame sizes (height of frame center is 63-355mm), power range is 0.12-400KW, which will make our country's increased safety motor reach the international advanced level of similar products in the 1980s.

High voltage (6kV) increased safety three-phase asynchronous motor series: YA355-450, power 160-450kW; Ya560-900, power 500-1800KW; Yam355-630 water-cooled, power 220-2500KW; YAKK355~630 air-air cooled, power 185 ~ 2000kW. The takw4000-20/2600 and 4000kW brushless excitation synchronous motors with increased safety produced in 1999 are new explosion-proof motors developed to meet the needs of petroleum deep processing and hydrogenation units in oil refineries.

Its characteristics are :(1) to meet the requirements of increased safety type explosion-proof motor, adopt a series of reliable measures to prevent spark, arc and dangerous high temperature, can operate safely in area 2 explosion danger place. (2) Brushless excitation is adopted, rotating rectifier plate and static excitation cabinet are set, and the excitation control system is reliable; Positive polarity slip excitation is accurate, no impact; The excitation system has reliable out-of-step protection and strong restep ability. The circuit design is reasonable, the discharge resistance does not heat in the work; Wide range of excitation current regulation. (3) synchronous machine, AC exciter and rotary

The rectifier plate is located between the main motor and the exciter, or outside the bearing seat. (4) The protection grade of the shell is IP54. (5) Grade F insulation is adopted, and temperature rise is assessed according to grade B. (6) Change the traditional water cooling to water cooling, that is, the water cooler is placed on the upper part of the motor. (7) Set the moisture-proof heater with increased safety, which is fixed in the cover at the bottom of the motor for heating and moisture-proof when stopping. (8) Choose high-quality raw materials, electrical and mechanical calculation with a large margin, can meet the operating reliability and increased safety type of motor temperature requirements. (9) Set up perfect monitoring measures; The main junction box is provided with an increased safety type self-balancing current transformer for differential protection; Stator windings buried work and spare platinum thermal resistance, the indexing number is Pt100; A water leakage monitoring instrument to monitor the leakage of the water cooler; Both ends of the seat type sliding bearings are respectively equipped with field temperature display instrument and remote signal terminal.

3. Positive pressure motor is a kind of positive pressure electrical equipment. Its structural characteristics are :(1) equipped with a complete set of ventilation system, there is no structural dead Angle inside the motor that may affect ventilation. (2) Housing and piping are made of non-combustible material and have sufficient mechanical strength. (3) Maintain sufficient positive pressure in the shell and main pipe relative to the outside atmosphere. (4) The motor must be equipped with safety protection devices (such as time relay and flow monitor) to ensure sufficient air change, and there must be automatic protection or alarm devices for pressure underpressure in the shell. (5) The quick opening or cover on the housing shall have an interlocking device with the power supply.

At present, there is no unified positive pressure motor series products in China.

4. Sparkless motor

Refers to the normal operating conditions, will not ignite the surrounding explosive mixture, and generally will not occur ignition failure of the motor. Compared with increased safety type motor, in addition to the insulation dielectric strength test voltage, winding temperature rise, te (at ambient temperature reached highest rated running after the final temperature of ac winding, since started by starting current meter to temperature rise to the limit of time) and starting current than not like increased safety type has special provisions, and other aspects to add safety type motor design requirements. Spark - free motor conforms to gb3836.1-83 and GB3836.8-87 "explosion-proof electrical equipment for explosive Environment spark - free electrical equipment" N ". The design pays attention to the sealing measures of the motor, the protection grade of the main body shell is IP54, IP55, and the junction box is IP55. For motors rated above 660V, connections for space heaters or other auxiliary devices shall be placed in separate junction boxes. At present, domestic has developed and produced YW series spark - free motor products (center height of the frame is 80~315mm). The explosion-proof mark is nIIT3, which is suitable for the site in zone 2 where the factory contains the combustible gas or the explosive mixture formed by steam and air in the temperature group T1-T3. The rated frequency is 50Hz, and the rated voltage is 380, 660, 380/660V. The motor is F insulated, but the temperature rise limit of the stator windings is assessed according to class B. It has a large temperature rise margin and high safety and reliability, and the power is 0.55~200kW. 5. Dust explosion-proof motor refers to the housing design and manufacture according to the prescribed conditions, can prevent the dust into the motor shell or cannot completely prevent dust to enter, but it into the quantity does not interfere with the safe operation of the motor, and internal dust accumulation is not easy to produce fire danger, when using, also won't cause around with explosive dust mixture explosion of the motor. Its characteristics are :(1) the shell has a high sealing, in order to reduce or prevent dust into the shell, even into, the amount of entry is not to form the ignition danger. (2) The maximum permissible temperature of the control shell surface shall not exceed the specified temperature group. At present, it has been used in the mechanized equipment of national grain storage. The national standard of dust explosion-proof electrical equipment is GBL2476.1-90 "Explosion-proof electrical equipment for explosive dust environment".

The development trend

1. Mine explosion-proof motor

(1) The development of high-power motor: at present, the world's largest installed capacity of coal shearer has exceeded 1200KW, and its driving motor power reaches 600kW; The maximum installed capacity of scraper conveyor in the working face of mining area has exceeded 1500kW, and the power of its driving motor has reached 725kW. The current domestic shearer driving motor maximum power is 400kW, scraper conveyor driving motor maximum power is 315kW. (2) The development of 3.3kV, 6kV and IOkV voltage level mining motor: this is because after the popularization of comprehensive mechanized coal mining unit, the trend of mining area is lengthened, resulting in the increase of voltage drop. Meanwhile, the use of high-power motor also requires the improvement of voltage level. (3) the development of mining double-speed motor: in order to adapt to the coal mine conveyor low-speed starting and high-speed operation of the work needs, foreign mining scraper conveyor are driven by double-speed motor. However, there is a certain gap between the power range, performance index and the performance of the matching control switch of the domestic mine two-speed motor and the foreign advanced level. (4) Improve the reliability of the mining motor: the working conditions of the mining explosion-proof motor are poor, the motor frequently starts with large loads, the load changes greatly, the voltage fluctuations are large, the ambient temperature is high and there is certain corrosion, etc., which all affect the reliability and life of the motor. (5) Speed up the renewal of mine explosion-proof motor. (6) Unified standard of mine explosion-proof motor.

2. Explosion-proof motors for petrochemical systems

(1) Increased safety type and sparkless motor demand will be on the rise. Petrochemical system users in the use of practice; The necessity of developing safety-increasing and sparkless motors in China has been recognized. In addition, a large number of the 1970 s [bow into the equipment form a complete set, no spark of increasing safety of the motor has to adopt a suitable alternative goods. (2) the reliability of the explosion-proof electric motor have been petrochemical system user attention increasingly. Petrochemical enterprise development has become increasingly large scale and continuous operation, the system to realize the long period operation and maintenance free or less maintenance. Therefore, explosion-proof motor has become the key equipment to ensure the above requirements. (3) explosion-proof and high efficiency variable frequency speed motor has become the petrochemical users urgent requirements to develop energy-saving products. In recent years, we have produced a series of YBx, YAX explosion-proof high efficiency motor, put into the market is very popular with users. One is to develop high-efficiency explosion-proof motor products, the other is to develop a large number of special products for explosion-proof speed regulating motor, especially the fan, pump and compressor with huge energy saving potential motor design for speed regulating motor