【简答题】有一台三相异步电动机,额定电压为380伏,三角形联接,若测出线电流为30安,那末通过每相绕组的电流等于()安。
【单选题】---What are you going to do this weekend? -----I’m going to help _____the city parks with my classmates to make them clean.
【单选题】What is the possible relationship between the speakers?
【单选题】编程时,并联线圈电路,从分支到线圈之间无触点的,线圈应放在(A)。
【单选题】On the one hand, he was highly praised by his teachers, but blamed by some of his classmates______.
【简答题】The new student is quite reserved. Never __________ him talking with his classmates. [A] did I find [B] I found [C] have I found [D] I have found
【简答题】有一台三相异步电动机,额定电压为220V,每相绕组的阻抗为100Ω,接在线电压为380V的三相电源上工作。 试求:电动机三相绕组应怎样连接?
【单选题】有一台三相异步交流电动机,每相绕组的额定电压为220V,对称三相电源的线电压为380V,则电动机的三相绕组应采用的联结方式是( )。
【简答题】一台笼型三相异步电动机,定子绕组Y形联结,其技术数据为:额定功率P N =40kW,额定线电压U 1N =380V,额定电流I N =87.2A,起动电流倍数K T =6.3,起动转矩倍数K st =1.2。要求该电动机起动时最大电流不超过350A,现有一台三相对称电抗器,每相电抗为X=0.3Ω。如果用该电动机拖动通风机工作,试问能否采用定子串接该电抗器减压起动?