【简答题】异步电动机拖动额定负载运行时,若电网电压过高或过低,会产生什么后果 ? 为什么 ?
【简答题】异步电动机拖动额定负载运行时,若电网电压过高或过低,会产生什么后果?为什么?
【简答题】阅读理解. We often talk about the weather. If we want to know about the weather, we can turn on (打开) the radio (收音机) and listen to the weather report. We can also turn on the TV and watch the Weather Repo...
【判断题】注射模具的分型面应选在塑件外形的最大轮廓处。
【单选题】下列属于表皮层特点的是
C.
有丰富的末梢神经、血管、淋巴管、毛发和腺体。
【简答题】一台三相4极、星形联结的异步电动机,额定值为:P N =1.7kW,U N =380V,I N =3.9A,n N =1445r/min。今拖动一恒转矩负载T L =11.38N·m连续运行,此时定子绕组平均温升已达到绝缘材料允许的温度上限。若电网电压下降为300V,在上述负载下电动机的转速为1400r/min,求此时电动机的铜耗为原来的多少倍?在此电网电压下该电动机能否长期运行下去(忽略励磁电流...
【简答题】阅读理解。 We often talk about the weather. If we want to know about the weather. We can turn on the radio and listen to the weather report. We can also turn on the TV and watch the Weather Show. And we ca...
【简答题】We often talk about the weather. If we want to know about the weather, we can turn on the radio and 小题1: the weather report. We can also turn on the TV and watch the Weather 小题2: . And we can ask othe...
【简答题】阅读理解。 We often talk about the weather. If we want to know about the weather, we can turn on the radio and listen to the weather report. We can also turn on the TV and watch the Weather Show. We can ju...