某三相繞線式異步電動機(jī),額定轉(zhuǎn)速Nn=940r/min,轉(zhuǎn)子靜止時每相感應(yīng)電動勢E20=130V,轉(zhuǎn)子電阻R2=0.1Ω,轉(zhuǎn)子電抗X20=0.9Ω。在額定轉(zhuǎn)速時,求: