为降低单相小功率电动机的转速,并兼顾节能,常采用降低电动机端电压的方法,即在电源与电动机之间串联一电容器以降低电动机两端电压。今通过试验已经测定,当电动机端电压降至180V时,最为合适,且此时电动机的等效电阻R=190Ω,电抗X L =260Ω。问:(1)应串联多大容量的电容器C,方能联接在U=220V,50Hz的电源上?(2)此电容器的耐压应为多大?(3)做出电阻、电感及电容三元件等效串联电路的电流及电压的。
【单选题】In an assembly drawing, there are 6 nuts which are used in bolt joints, and there is another nut which has the same size and of the same type with the others, and then how many part nubmer should be g...
【简答题】How many competitors from how many country take part in the 27 th Summer Olympics in Sydney?A. Over
10,000 athletes; 119 countries B. Over
10,000 athletes; 184 countries