题目内容

某三相绕线式异步电动机,当转子绕组中串入调速电阻后,当负载转矩不变时,则调速后的电机转速( )。

A. 增加
B. 减少
C. 基本不变

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双速三相交流鼠笼式异步电动机常用的改变转速的方法是( )。

A. 改变电压
B. 改变极对数
C. 将定子绕组由三角形连接改为星形连接

三相异步电动机拖动恒转矩负载,当进行变极调速时,应采用的联接方式为( )。

A. Y-Y Y
B. △-Y Y
C. 顺串Y-反串Y

选择异步电动机调速方法的基本原则是,调速范围广、调速平滑性好、调速设备简单、调速中的损耗小。()

A. 对
B. 错

Directions: Watch the video clip and complete the sentences.1. Kate: I tried to make her laugh, told her not to worry about it, and that ____________.2. Mark: Maybe she was just being polite. It was probably because she realized you were working and ____________.3. Kate: I just wonder if she found it difficult to talk about her feelings with me. Maybe I shouldn’t have tried to make her laugh? Perhaps she thought I wasn’t ____________.4. Mark: I wouldn’t worry about it. ____________.5. Janet: Yes, I’ve just got my essay back. ____________!

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