Development of yb800-2 2500kw flameproof high speed self lubricating three phase asynchronous motor

2020-09-24

< P style = 'text align: Center;' > Chen Xingwei < / P > < P style = 'text align: Center; '> (Jiamusi Motor Co., Ltd) < / P > < p > Abstract: This paper introduces the design points of large capacity 2p flameproof high-speed self-lubricating three-phase asynchronous motor. Starting from the aspects of controlling motor bearing bush heating and improving heat dissipation capacity, the measures taken to control stator temperature rise and strengthen bearing heat dissipation capacity are mainly introduced. The key words are flameproof motor; high speed; self-lubricating; bearing bush < / P > < p > 0 Introduction < / P > < p > because most of the oil transmission pipelines are in the wild, the power supply conditions and control protection of the motor supporting the oil pump are limited by the environment. Generally, the explosion-proof high-speed self-lubricating motor is used, which saves the oil station and its control system, so the investment is small and the fault link is small 。 However, as the matching motor of the pump is generally 3000 rpm high-speed motor, when the motor capacity is more than 2000 kW and above, the heat generated by the motor bearing pad lubrication is difficult to cool down by itself. This paper analyzes the key points of the development of large-scale self-lubricating flameproof motor. < / P > < p > at present, the forced lubrication is adopted for the two largest capacity flameproof sliding bearing motors in China. The reason is that the sliding bearing and the shaft are in surface contact. When the motor rotates, the friction between the shaft and the bearing bush will generate a lot of heat, most of which is taken away by the flowing lubricating oil (that is, the flowing lubricating oil not only plays the role of lubrication but also plays the role of cooling), while the self-lubricating motor only has the function of lubrication Depending on its own heat dissipation, it is easy to cause high temperature of bearing bush, so controlling the temperature of bearing bush is the primary key technology of the motor < / P > < p > according to the design manual of AC motor [1], the key point of bearing bush heating of high-speed self-lubricating motor lies in how to reduce the heat generated by the bearing bush and how to dissipate the heat as soon as possible The yb800-2 2500kw flameproof high-speed self-lubricating three-phase asynchronous motor is analyzed and demonstrated. Determination of electromagnetic design scheme [2] < / P > < p > 1.1 Basic parameters of motor motor < / P > < p > A) power: 2500kw < / P > < p > P > b) power: 2500kw < / P > < p > b) rated voltage: 6kV < / P > < p > C) rated current: 288A < / P > < p > D) rated frequency: 50Hz < / P > < p > < p > e) rated speed: 2985r / min / min < / P > < p > F) protection level: main body IP54, junction box IP55 < / P > < p > G) protection level: Main IP54, junction box IP55 < / P > < p > G) thermal classification: 155 (f < p > < p > H) explosion protection level: Exd II BT4 < / P > < p > < p > P > I) working system: working system: S1 < / P > < p > < p cooling mode: ic511 < / P > < p > k) installation side Formula: IMB3 < / P > < p > L) rotation direction: clockwise < / P > < p > m) efficiency: 94.0% < / P > < p > n) power factor: 0.89 < / P > < p > o) locked rotor torque multiple: 0.6 < / P > < p > P) maximum torque multiple: 1.80 < / P > < p > q) locked rotor current multiple: 6.5 < / P > < p > 1.2 The basic principle of electromagnetic design < / P > < p > considering the requirements of motor self lubrication, the electromagnetic scheme of the motor is designed in accordance with two principles [3]: < / P > < p > A) the temperature rise design of the motor should be as low as possible to avoid that the temperature of the contact part between the bearing bush and the internal air circuit of the motor is too high due to the high internal air temperature of the motor, and the bearing shell cannot be cooled or even heated. < / P > < p > b) the rotor of the motor shall be reduced as far as possible. The cast aluminum rotor and high-strength rotating shaft shall be used to shorten the rotor core as far as possible, so as to reduce the load of bearing bush and reduce the calorific value. < / P > < p > the load borne by the motor bearing mainly comes from the weight of the rotor and the unilateral magnetic pull caused by the non concentricity of the stator and rotor. In order to reduce the load borne by the bearing bush, the three circles of the motor [4] should be fully considered in the design, and the outer diameter of the rotor should be reduced as far as possible within the allowable range of various loads, so as to reduce the weight of the iron core. The lighter weight cast aluminum rotor should be selected in the guide bar material. < / P > < p > 1.3 design of insulation system < / P > < p > in order to reduce the temperature rise, the most advanced epoxy anhydride paint and its matching less glue insulation structure (main insulation thinned to 1.0mm, turn to turn insulation 0.4mm, without slot lining) are adopted. At the same time, vacuum pressure impregnation is used to solidify the insulation system into a whole, which not only improves the utilization rate of the slot, but also facilitates the heat dissipation of the winding [5]. In order to determine the electromagnetic load and estimate the temperature rise, it is necessary to consider not only the self lubrication of bearing bush to reduce the temperature rise of motor, but also the proper reduction of rotor weight and bearing load. Therefore, combined with the previous tests of similar motors, the stator electrical density is set as 2.66a/mm < sup > 2 < / sup > and the thermal load is set to 1750a2 / cm & middot; mm < sup > 2 < / sup >. According to the electromagnetic calculation and previous test data, as well as the temperature rise calculation formula of Siemens company in Germany, the temperature rise of this design motor is estimated as 63.9k. < / P > < p > 2 overall structure and structural design of main parts and components < / P > < p > 2.1 Overall structure < / P > < p > motor structure installation form IMB3; cooling mode is ic511; protection grade is IP54; protection grade of junction box is IP55; cylindrical single shaft extension; end cover sliding bearing self-lubricating; cast aluminum rotor structure; the stator adopts buckle plate external pressure structure; the inside of motor adopts radial ventilation structure with both sides symmetry; the motor has two axial-flow internal fans; the external fan adopts the external fan A backward inclined centrifugal fan is used. The specific structure is shown in Fig. 1.

< / P > < p > 2.2 design of flameproof enclosure structure [6-8] < / P > < p > the motor adopts explosion-proof structure. The frame shell is made of 12 steel plate Q235A, and the two end plates are 50 steel plate Q235A. Eight reinforcing ribs are welded in the frame. Cooling pipes are distributed around the engine base, and the cooling pipes are fixed on the end plate of the engine base by stretching process. < / P > < p > the end cover and the engine base are matched with the flame-proof surface of the stop, the junction box and the frame are of plane flameproof surface, and the push cover type flame-proof structure is adopted at the shaft through position. The explosion-proof principle is that there is a diameter difference of 0.15-0.2mm between the push cover and the shaft, which can not only ensure the sliding cover to move freely on the shaft, but also greatly reduce the axial explosion-proof gap, improve the safety, and push the cover through The key on the shaft rotates with the shaft, and there is no relative friction, which avoids the possibility of easily holding the shaft due to the small clearance. When the explosion occurs in the inner cavity of the engine base, the explosion pressure pushes the cover to move outward and collide with the bearing sleeve, blocking the propagation path of the explosion flame and playing the role of explosion-proof. At the same time, since the sliding cover can adjust the radial friction through free movement on the shaft, the wear of the push cover is very slight. According to the provisions of the explosion-proof standard, anti rust measures are required for the flame-proof surface. The flame-proof surface matched with the sliding cover is made of stainless steel, including stainless steel shaft sleeve (interference fit with shaft), inner sleeve and baffle plate. The sliding cover is made of wear-resistant material silicon brass. Silicon brass and stainless steel are not easy to produce sparks, which improves the safety of motor operation. The specific structure is shown in Figure 2.

2.3 Measures to reduce the heat generation of bearing bush < / P > < p > as the motor speed is fixed, in order to reduce the heat output of the bearing bush, only by reducing the journal to reduce the linear speed and improving the oil film quality can reduce the friction loss. Therefore, the high-quality alloy forging steel 42CrMo [9] is selected for the shaft material of the motor, and the quenching and tempering treatment is carried out. The strength and hardness of the alloy steel after quenching and tempering are strengthened The sample can reduce the journal as much as possible in the range of strength. Through the strength calculation, the diameter of the bearing pad of the motor can be reduced from the normal & phi; 140mm to & phi; 110mm, and the linear speed can be effectively reduced and the calorific value can be reduced. < / P > < p > in order to improve the quality of oil film, the lubricating oil grade is determined according to the motor speed and the load on the bearing bush, and the double oil ring structure is selected in the bearing shell structure. During assembly, the bearing bush is scraped and grinded to ensure the formation of convergence wedge-shaped gap between the shaft and the bearing bush, which is more conducive to the formation of oil film during operation.

2.4 Reduce the heat transfer to the bearing bush < / P > < p > when the motor is running, the temperature rise generated by the rotor will be directly transmitted to the bearing bush through the shaft. In the inner cavity of the motor, the high temperature air generated by the stator temperature rise is directly blown to the bearing Bush, which will also cause the temperature rise of the bearing bush. Therefore, the motor temperature rise is strictly controlled in the design of the motor. At the same time, a push cover assembly is added in the frame to connect the bearing bush with the frame The inner cavity is separated to prevent the high temperature air from the inner chamber of the engine base from blowing directly to the bearing bush. < / P > < p > 2.5 improve the bearing bush structure < / P > < p > the motor adopts the self-lubricating oil ring of the end cover sliding bearing. According to the requirements of the technical agreement, the bearing temperature does not exceed 95 ℃ and the oil temperature does not exceed 65 ℃. After the calculation of the bearing temperature rise, the model of the motor bearing is determined as dqz12-110b / BJ, and the specific structure size of the bearing is shown in Fig. 3 [10].

< / P > < p > in the design of bearing pedestal, this series of bearings have larger heat dissipation area, and increase the oil storage capacity in the oil chamber, which increases the heat dissipation area of the bearing. After installation, the whole tile ball is located outside the motor cavity, which is more conducive to heat dissipation. At the same time, the bearing is equipped with two oil rings, which increases the oil carrying capacity of the oil ring, which can meet the requirements of full film lubrication, accelerate the lubricating oil circulation speed and promote the hot intersection Change. The results are as follows. < / P > < p > through the improvement, the temperature rise of the bearing under the rated condition is calculated under the existing conditions. < p > < p > motor speed: 2985r / min < / P > < p > radial load of each bearing: 12205n < / P > < p > bearing relative clearance: 1.9 & permil; < / P > < p > minimum oil film thickness: 25 & mu; M < / P > < p > lubrication mode: self lubrication < / P > < p > lubricating oil grade: isovg32 < / P > < p > bearing temperature rise: 32K < / P > < p > 2.6 strengthen the cooling of bearing bush < / P > < p > combined with the previous test results of our company, the bearing shell temperature at the motor tail end is 8 ℃ ~ 13 ℃ lower than that at the shaft extension end due to the indirect cooling of the external fan, which shows that the cooling effect of the fan on the bearing shell is very considerable. Therefore, in the design of the motor, an axial fan is added at the shaft extension end of the motor, which can effectively take away the heat generated by the bearing bush at the extension end in time, and reduce the temperature of the bearing bush at the shaft extension end.

2.7 Avoid direct sunlight < / P > < p > since the motor is used in unattended outdoor places, when the sun directly shines on the bearing bush, the temperature of the bearing bush will also rise. Therefore, a protective cover is added at the shaft extension end of the motor, which can not only make the wind path of the axial fan at the shaft extension end more smooth, but also avoid direct sunlight. By taking the above measures, the motor has passed the type test at one time. The stator temperature of the motor rises 63.5k, and the temperature of the bearing bush does not exceed 85 ℃ when the maximum ring temperature is 40 ℃. In addition, the on-line test with the pump has been carried out, and all performance tests have been passed. [1] Fu Fengli, Tang Xiaohao. AC motor design manual [M]. Hunan: Hunan people's publishing house, 1978. < / P > < p > [2] Chen Xingwei, Yu Zhaosheng. Optimization design of high efficiency flameproof motor [J]. Explosion proof motor, 2009,44 (1): 15-18. < / P > < p > [3] Yang Wanqing, Liu Jianzhong. Design, installation and maintenance of practical asynchronous motor [M]. Beijing: Machinery Industry Press, 1996. < / P > < p > [4] Chen Shikun. Motor design [M]. Beijing: China Machine Press, 2000. < / P > < p > [5] Tang yunqu. Electrical engineering [M]. Beijing: China Machine Press, 2000. < / P > < p > [6] gb3836.1-2010, explosive environment Part 1: General requirements for equipment [S]. < / P > < p > [7] gb3836.2-20