【正文】 n 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(jī)引線連接到變壓器的低壓側(cè)。見圖 3。離心式或平方曲線可以在許多情況下，假設(shè)，但也有一些應(yīng)用，這將是有問題的。汽車制 造商將需要轉(zhuǎn)速扭矩曲線和驅(qū)動(dòng)設(shè)備的慣性，當(dāng)他們驗(yàn)證他們的設(shè)計(jì)。降低電壓的電壓降低的方法的目的是降低電機(jī)起動(dòng)電流對(duì)電力系統(tǒng)的電壓控制，電機(jī)將在終端。這種現(xiàn)象的一個(gè)例子是在附錄中列出了。這可能會(huì)導(dǎo)致在電機(jī)端子實(shí)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(jī)是驅(qū)動(dòng)大慣性負(fù) 載，電機(jī)可以改變與勵(lì)磁發(fā)電機(jī)行動(dòng)。 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(jī)的引線電容器，電容器可以在電動(dòng)機(jī)的電源已斷開，繼續(xù)提供磁化電流。時(shí)間常數(shù)表明剩余電壓在電機(jī)額定電壓衰減到 %的功率損失后所需的時(shí)間。電容器不應(yīng)尺寸大于磁化電流的電機(jī)除非他們可以斷開電機(jī)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(jī)損壞， 須特別小心，以確保電容器作為電機(jī)達(dá)到額定轉(zhuǎn)速的刪除，或在斷電時(shí)使電機(jī)不會(huì)從電容器提供勵(lì)磁電流，發(fā)電機(jī)模式。電角度。應(yīng)用系統(tǒng)的電壓的乘積這功分量可測(cè)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(zhuǎn)子扭矩可增加對(duì)設(shè)備的磨損，甚至導(dǎo)致災(zāi)難性的故障，如果負(fù)載不能處理在盯著由電機(jī)產(chǎn)生的轉(zhuǎn)矩。此外，電壓條件下監(jiān)測(cè)許多控制系統(tǒng)，一個(gè)潛在的問題，可以采取離線運(yùn)行電動(dòng)機(jī)全電壓起動(dòng)時(shí)。開發(fā)的感應(yīng)電動(dòng)機(jī)的轉(zhuǎn)矩變化大致為所施加的電壓的平方。如果電機(jī)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(jī)端子，但整個(gè)電源總線送起動(dòng)電機(jī)。這種方法將使電機(jī)產(chǎn)生最高的起動(dòng)轉(zhuǎn)矩和 提供最短的加速時(shí)間。全壓全電壓起動(dòng)方法，也被稱為直接起動(dòng)，是采用最簡單的方法，具有最低的設(shè)備成本，是最可靠的。這種熱導(dǎo)致這些部件的附加應(yīng)力，可以 有一個(gè)影響電機(jī)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(duì)電機(jī)的加速負(fù)載的時(shí)間是依賴于負(fù)載的慣量和電動(dòng)機(jī)的轉(zhuǎn)矩與負(fù)載曲線之間的邊緣，有時(shí)也被稱為加速轉(zhuǎn)矩。最后是擊穿扭矩（ BDT）被定義為最大轉(zhuǎn)矩，電機(jī)的發(fā)展。第一個(gè)是鎖定轉(zhuǎn)子扭矩（ LRT），最小轉(zhuǎn)矩，電機(jī)將在剩下的所有的角位置的轉(zhuǎn)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(fù)載能加速，電機(jī)必須產(chǎn)生更大的扭矩比負(fù)荷要求。正確的選擇會(huì)涉及的任何權(quán)力制約制度進(jìn)行徹底的調(diào)查，以加速負(fù)載設(shè)備的整體成本。這些，連同全電壓，或直接起動(dòng)，給買方的汽車種類繁多的時(shí)候指定在 給定的應(yīng)用程序中使用的電機(jī)。降壓起動(dòng)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(dòng)異步電動(dòng)機(jī)