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外文翻譯--感應電動機的起動方法和問題-其他專業(yè)-文庫吧資料

2025-01-27 10:09本頁面
  

【正文】 can be done in either a closed circuit transition, or an open circuit transition method. In the open circuit method the connection to the voltage is severed as it is changed from the reduced voltage to the line level. Care should be used to make sure that there will not be problems from transients due to the switching. This potential problem can be eliminated by using the closed circuit transition. With the closed circuit method there is a continuous 電機引線連接到變壓器的低壓側。見圖 3。離心式或平方曲線可以在許多情況下,假設,但也有一些應用,這將是有問題的。汽車制造商將需要轉速扭矩曲線和驅動設備的慣性,當他們驗證他們的設計。降低電壓的電壓降低的方法的目的是降低電機起動電流對電力系統(tǒng)的電壓控制,電機將在終端。這種現(xiàn)象的一個例子是在附錄中列出了。這可能會導致在電機端子實際上在上升至近 50%,在某些情況下,額定電壓在電壓。如果電機是驅動大慣性負載,電機可以改變與勵磁發(fā)電機行動。 With capacitors connected to the leads of the motor, the capacitors can continue to supply magizing current after the power to the motor has been disconnected. This is indicated by a longer time constant for the system. If the motor is driving a high inertia load, the motor can change over to generator action with the magizing . 與連接到電機的引線電容器,電容器可以在電動機的電源已斷開,繼續(xù)提供磁化電流。時間常數(shù)表明剩余電壓在電機額定電壓衰減到 %的功率損失后所需的時間。電容器不應尺寸大于磁化電流的電機除非他們可以斷開電機在斷電的情況下。 B. Power Factor Correction Capacitors can also be left permanently connected to raise the full load power factor. When used in this manner they are called power factor correction capacitors. The capacitors should never be sized larger than the magizing current of the motor unless they can be disconnected from the motor in the event of a power loss. 。為了避免過電壓和電機損壞,須特別小心,以確保電容器作為電機達到額定轉速的刪除,或在斷電時使電機不會從電容器提供勵磁電流,發(fā)電機模式。電角度。應用系統(tǒng)的電壓的乘積這功分量可測變量(乏)。電角度的要求。 The large reactive currents required by the motor lag the applied voltage by 90 electrical degrees. This reactive power doesn39。見圖 2。這種沖擊加載由于暫態(tài)扭矩可超過 600%的鎖定轉子扭矩可增加對設備的磨損,甚至導致災難性的故障,如果負載不能處理在盯著由電機產(chǎn)生的轉矩。此外,電壓條件下監(jiān)測許多控制系統(tǒng),一個潛在的問題,可以采取離線運行電動機全電壓起動時。開發(fā)的感應電動機的轉矩變化大 致為所施加的電壓的平方。如果電機是電力系統(tǒng)薄弱,突然的高功耗可引起電壓暫降,不僅在電機端子,但整個電源總線送起動電機。這種方法將使電機產(chǎn)生最高的起動轉矩和提供最短的加速時間。全壓全電壓起動方法,也被稱為直接起動,是采用最簡單的方法,具有最低的設備成本,是最可靠的。這種熱導致這些部件的附加應力,可以有一個影響電機的壽命。 The time it takes for the motor to accelerate the load is dependent on the inertia of the load and the margin between the torque of the motor and the load curve, sometimes called accelerating torque. In general, the longer the time it takes for the motor to accelerate the load, the more heat that will be generated in the rotor bars, shorting ring and the stator winding. This heat leads to additional stresses in these parts and can have an impaction motor life. 這需要對電機的加 速負載的時間是依賴于負載的慣量和電動機的轉矩與負載曲線之間的邊緣,有時也被稱為加速轉矩。最后是擊穿扭矩( BDT)被定 義為最大轉矩,電機的發(fā)展。第一個是鎖定轉子扭矩( LRT),最小轉矩,電機將在剩下的所有的角位置的轉子。s speedtorque curve. The first is lockedrotor torque (LRT) which is the minimum torque which the motor will develop at rest for all angular positions of the rotor. The second is pullup torque (PUT) which is defined as the minimum torque developed by the motor during the period of acceleration from rest to the speed at which breakdown torque occurs. The last is the breakdown torque (BDT) which is defined as the maximum torque which the motor will develop. If any of these points are below the required load curve, then the motor will not start. 為了使負載能加速,電機必須產(chǎn)生更大的扭矩比負荷要求。正確的選擇會涉及的任何權力制約制度進行徹底的調查,以加速負載設備的整體成本。這些,連同全電壓,或直接起動,給買方的汽車種類繁多的時候指定在給定的應用程序中使用的電機。降壓起動自耦變壓器, Y 形三角洲,功率因數(shù)校 正 INTRODUCTION There are several general methods of starting induction motors: full voltage, reduced voltage, wyesdelta, and part winding types. The reduced voltage type can include solid state starters, adjustable frequency drives, and autotransformers. These, along with the full voltage, or across the line starting, give the purchaser a large variety of automotives when it es to specifying the motor to be used in a given application. Each method has its own benefits, as well as performance trade offs. Proper selection will involve a thorough investigation of any power system constraints, the load to be accelerated and the overall cost of the equipment. 簡介 : 有起動異步電動機的
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