直流電機(jī)原理(編輯修改稿)
2024-09-01 10:12 本頁面
【文章內(nèi)容簡(jiǎn)介】 100 200 300 400 500 600 700 CURRENT (%) Torque rises instantaneously to LRT levels. This causes a torque transient that can be damaging. 電流瞬間上升至 LRC水平，由此引起的電流瞬變具有破壞性。 Typical torque falls from LRT to Pull Out Torque before rising to Breakdown Torque just before full speed. 電機(jī)達(dá)到滿速前，典型轉(zhuǎn)矩在升至失步轉(zhuǎn)矩前由 LRT降至脫扣力矩。 Motor Start Theory 14 0 50 100 150 200 250 300 100 90 80 70 60 50 40 30 20 10 0 SLIP (%) FULL LOAD TORQUE (%) 0 100 200 300 400 500 600 700 CURRENT (%) Full Voltage Starting Limitations 滿電壓起動(dòng)限制 1. Current transient 電流瞬變 1 2. Current magnitude 電流值 2 3. Torque transient 扭矩瞬變 3 4 4. Torque magnitude 扭矩值 Reduced voltage starting attempts to overe these limitations by applying the voltage gradually. 降壓起動(dòng)通過逐漸利用滿電壓的方式力圖克服這些限制。 Motor Start Theory 15 0 50 100 150 200 250 300 100 90 80 70 60 50 40 30 20 10 0 SLIP (%) FULL LOAD TORQUE (%) 0 100 200 300 400 500 600 700 CURRENT (%) Reduced Voltage Starting 降壓起動(dòng) I ST = LRT x T ST LRC ( ) 2 Reduces start torque by the square of the current reduction. 起動(dòng)扭矩減少值是電流降低值的平方。 Current can only be reduced to the point where torque output from the motor exceeds the torque required by the load. 電流只能降到電機(jī)扭矩輸出超過負(fù)載要求的扭矩的那個(gè)點(diǎn) Reduces start current. 降低起動(dòng)電流。 Motor Start Theory 16 Reduced Voltage Starting 降壓起動(dòng) To be effective, a reduced voltage starter must allow the motor to accelerate to around 90% speed before applying full voltage. 為確保有效運(yùn)行 ， 降壓起動(dòng)器須使電機(jī)在使用滿電壓之前加速到 90％ 左右 Below this speed the current will step through to almost LRC levels thus removing any benefit from the reduced voltage starter. 如果低于此速度 ， 電流將逐步達(dá)到LRC水平，從而失去降壓起動(dòng)器的任何優(yōu)點(diǎn)。 0 50 100 150 200 250 300 100 90 80 70 60 50 40 30 20 10 0 SLIP (%) FULL LOAD TORQUE (%) 0 100 200 300 400 500 600 700 CURRENT (%) Small Reduction at 50% speed Large Reduction at 95% speed Motor Start Theory 17 Electromechanical 機(jī)電 Autotransformer 自耦變壓器 Primary Resistance 一次電路電阻 Star/Delta 星形 /三角形 Electronic 電子 Soft Start 軟起動(dòng) Reduced Voltage Starters 降壓起動(dòng)器 Motor Start Theory 18 Autotransformers 自耦變壓器 Thermal Overload 3 Phase Auto Transformer (B) Start Contactor (A) Start Contactor Run Contactor 3 ~ M The Autotransformer Starter employs an autotransformer to reduce the voltage during the start period. The transformer has a range of output voltage taps that can be used to set the start voltage. 超動(dòng)期間 自耦變壓器起動(dòng)器使用自耦變壓器降低電壓。變壓器有一套輸出電壓開關(guān)，可用以設(shè)置起動(dòng)電壓。 The motor current is reduced by the start voltage reduction, and further reduced by the transformer action resulting in a line current less than the actual motor current. 電機(jī)電流隨起動(dòng)電壓下降而降低，且通過變壓器的作用進(jìn)一步降低最后產(chǎn)生的線路電流小于電機(jī)實(shí)際電流。 Motor Start Theory 19 0 50 100 150 200 250 300 100 90 80 70 60 50 40 30 20 10 0 SLIP (%) FULL LOAD TORQUE (%) 0 100 200 300 400 500 600 700 CURRENT (%) 60% Tap 60%分接頭 Autotransformers 自耦變壓器 L
環(huán)評(píng)公示相關(guān)推薦
鄂ICP備17016276號(hào)-1