听对话,回答问题。 1. What was wrong with the man? A. He had a headache. B. He had a stomachache. C. He had a toothache. 2. How does the man feel now? A. Quite all right. B. Much better. C. Not very well.
【简答题】一台三相笼型异步电动机 ,其铭牌数据如下表所示。 f P N U N 接法 n N h N cos j N I st / I N T st / T N 50HZ 20KW 220/380V Δ /Y 970 r/min 91.5% 0.84 7.0 2.0 试求以下参数: ( 1 )若电源电压为 380V ,电机应采取何种方式接线? ( 2 )若电源电压为 220V ,电机 Δ 接线接在自耦降压器...