【简答题】一台绕线转子感应电动机,已知P N =75kW,U N1 =380V,n N =720r/min,I N1 =148A,η N =90.5%,cosΦ N1 =0.85,λ m =2.4,E N2 =213V,I N2 =220A,用于“起吊重物,当电动机转子转45转,重物上升1m,如果要求带动额定负载以8m/min的速度上升,问转子每相应串联多大电阻?
【简答题】一台绕线转子感应电动机,已知P N =75kW,U N1 =380V,n N =720r/min,I N1 =148A,η N =90.5%,cosΦ N1 =0.85,λ m =2.4,E N2 =213V,I N2 =220A,带动一位能负载,T z =T N ,采用倒拉反接自动下放负载,要求下放转运为300r/min,试问转子每相应串联多大电阻?
【简答题】一台绕线转子感应电动机,已知P N =75kW,U N1 =380V,n N =720r/min,I N1 =148A,η N =90.5%,cosΦ N1 =0.85,λ m =2.4,E N2 =213V,I N2 =220A,试用机械特性的实用表达式绘制电动机的固有机械特性和转子串入0.0448Ω电阻时的人为机械特性(注:转子绕组星形联结)。