【文章內(nèi)容簡介】 of power. This is typically one to three seconds without capacitors. 另外的電容器將改變有效開路時間常數(shù)的電機(jī)。時間常數(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間。這通常是一個三秒的無電容器。 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，電容器可以在電動機(jī)的電源已斷開，繼續(xù)提供磁化電流。這是一個較長的時間常數(shù)為系統(tǒng)顯示。如果電機(jī)是驅(qū)動大慣性負(fù)載，電機(jī)可以改變與勵磁發(fā)電機(jī)行動。 Current from the capacitors and the shaft driven by the load. This can result in the voltage at the motor terminals actually rising to nearly 50% of rated voltage in some cases. If the power is reconnected before this voltage decays severe transients can be created which can cause significant switching currents and torques that can severely damage the motor and the driven equipment. An example of this phenomenon is outlined in the appendix. 從電容器和軸驅(qū)動的負(fù)載電流。這可能會導(dǎo)致在電機(jī)端子實際上在上升至近 50%，在某些情況下，額定電壓在電壓。如果重新連接電源之前，這個電壓衰減嚴(yán)重的瞬變可以創(chuàng)建可引起明顯的開關(guān)電流和扭矩，會嚴(yán)重?fù)p壞電機(jī)和驅(qū)動設(shè)備。這種現(xiàn)象的一個例子是在附錄中列出了。 Ill. REDUCED VOLTAGE Each of the reduced voltage methods are intended to reduce the impact of motor starting current on the power system by controlling the voltage that the motor sees at the terminals. It is very important to know the characteristics of the load to be started when considering any form of reduced voltage starting. The motor manufacturer will need to have the speed torque curve and the inertia of the driven equipment when they validate their design. The curve can be built from an initial, or break away torque, as few as four other data points through the speed range, and the full speed torque for the starting condition. A centrifugal or square curve can be assumed in many cases, but there are some applications where this would be problematic. An example would be screw pressors which have a much higher torque requirement at lower speeds than the more mon centrifugal or fan load. See Fig. 3. By understanding the details of the load to be started the manufacturer can make sure that the motor will be able to generate sufficient torque to start the load, with the starting method that is chhosen. 生病。降低電壓的電壓降低的方法的目的是降低電機(jī)起動電流對電力系統(tǒng)的電壓控制，電機(jī)將在終端。這是了解負(fù)載的特點是啟動時考慮任何形式的降壓起動很重要。汽車制造商將需要轉(zhuǎn)速扭矩曲線和驅(qū)動設(shè)備的慣性，當(dāng)他們驗證他們的設(shè)計。該曲線可由初始，或脫離扭矩，只有其他四個數(shù)據(jù)點的速度范圍內(nèi)，和全轉(zhuǎn)速轉(zhuǎn)矩的起動條件。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。一個例子是，螺桿壓縮機(jī)具有更高的扭矩要求在較低的速度比一般離心泵或風(fēng)機(jī)負(fù)載。見圖 3。通過了解負(fù)載的細(xì)節(jié)必須開始制造商可以確保電機(jī)能產(chǎn)生足夠的轉(zhuǎn) 矩啟動負(fù)載，具有起動方法， chhosen。 A. Autotransformer 答：自耦變壓器 The motor leads are connected to the lower voltage side of the transformer. The most mon taps that are used are 80%, 65%, and 50%. At 50% voltage the current on the primary is 25% of the full voltage locked rotor amps. The motor is started with this reduced voltage, and then after a preset condition is reached the connection is switched to line voltage. This condition could be a preset time, current level, bus volts, or motor speed. The change over 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(jī)引線連接到變壓器的低壓側(cè)。這是最常用的水龍頭 80%， 65%，和 50%。在 50%上的電壓電流是 25%次全電壓鎖定轉(zhuǎn)子電流。 電機(jī)啟動這個降低的電壓，然后在一個預(yù)先設(shè)定的條件達(dá)到連接切換到線電壓。這種情況可能是一個預(yù)先設(shè)定的時間，目前的水平，總線伏，或電機(jī)速度。的變化可在一個閉合電路的過渡，還是一個開放的電路轉(zhuǎn)換的方法。在開放電路電壓的連接方法是作為它是從低電壓變?yōu)樗骄€。護(hù)理應(yīng)用于確保不會有問題，從瞬變由于開關(guān)。這個潛在的問題可以通過使用閉路過渡消除。與閉回路法有一個連續(xù)的 Voltage applied to the motor. Another benefit with the autotransformer starting is in possible lower vibration and noise levels during starting. 施加到電動機(jī)的電壓。在啟動過程中的另一個好處與自耦變壓器起動在盡可能低的振動和噪音水平。 Since the torque generated by the