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Te s 1 TL 電機(jī)學(xué)習(xí)題課 Electric Machinery 10 注意 將下降時(shí),當(dāng)所加電阻大于此值所串入的電阻為:最大轉(zhuǎn)矩,此時(shí),起動(dòng)轉(zhuǎn)矩至多可達(dá)到當(dāng)轉(zhuǎn)子回路串入電阻時(shí)steistTRkckXcXRR 222121( m a x ))(????? ??減小此時(shí)增加不夠多,下降很多,而增大很多,從而使)當(dāng)轉(zhuǎn)子電阻(保持不變不變時(shí),下降,但兩者乘積保持增加而)當(dāng)(增大下降不多時(shí),的增加很多而)當(dāng)(的變化有三種可能:知:起動(dòng)轉(zhuǎn)矩由增加知:所以由增加。所以增加減小,增大,起動(dòng)電流總阻抗時(shí),發(fā)生以下情況:當(dāng)增大轉(zhuǎn)子電阻stmstststmststmststmTstmwmststkTIRTITITICTkNfEZIUEXRRIZR222221111112222222c o s3c o s2c o s1c o s,c o s????????????????????????????電機(jī)學(xué)習(xí)題課 Electric Machinery 11 下降知:由下降。知:起動(dòng)轉(zhuǎn)矩由減小,增加,起動(dòng)電流總阻抗當(dāng)增大轉(zhuǎn)子電抗時(shí),m a x21121121211m a x221221122112212212211)(4)(2])()[(2])()[(TXXfpUmXXUmTTXXRcRfRpUmXXRcRRUmTIZSstSststk????????????????????????????????電機(jī)學(xué)習(xí)題課 Electric Machinery 12 518有一臺(tái) 50Hz、 380V的的三相感應(yīng)電動(dòng)機(jī) ,若運(yùn)行在 60Hz、 380V的電源上 ,問(wèn)電動(dòng)機(jī)的最大轉(zhuǎn)矩、起動(dòng)轉(zhuǎn)矩和起動(dòng)電流有何變化 ? m a xm a xm a x21121121211m a x221221122112212212211212111111165)(4)(265])()[(2])()[()(6050TTTXXfpUmXXUmTTTTXXRcRfRpUmXXRcRRUmTIXXNfXHzfHzfUNkfU