【简答题】一台三相同步电动机的数据如下:额定功率P N =2000kW,额定电压U N =3000V(星形联结),额定功率因数cosφ N =0.9(超前),额定效率η N =80%,同步电抗X s =1.5Ω,忽略定子电阻。当电动机的电流为额定值,cosφ=1时,励磁电流为5A。如功率改变,电流变为0.9I N ,cosφ=0.8(超前),求此时的励磁电流(设空载特性为一直线)。
【简答题】Imperfect
competition results from ______.A. monopoly in government policies B. monopoly in natural resources C. differentiated products D. t he advantages of increasing returns
of economics of scale.
【单选题】Consider Figure 5.3. Assume that Swedish import companies behave as a monopoly buyer while foreign export companies behave as competitive sellers. Compared to free trade, Sweden's import quota results...