问题 问答题 简答题

电动机定子线圈绝缘损坏的原因有哪些?

答案

参考答案:

电动机定子线圈绝缘损坏的原因有:

(1)经常超负荷运行,绕组经常过热,绝缘因受热老化;

(2)制造工艺不良或槽楔打得不紧,使线圈在槽内松动,或端部绑扎不牢,绝缘层受损;

(3)电动机使用日久,绝缘老化;

(4)电动机受潮或受腐蚀,绝缘值降低;

(5)铁屑、焊渣等铁磁物质落入线圈表面或槽壁,在交变磁场的作用下产生振动,使线圈绝缘层被磨损;

(6)电动机扫膛,槽温升高,使槽内线圈绝缘迅速老化。

阅读理解

A young father was visiting an old neighbor. They were standing in the old man’s garden, and talking about children. The young man said,“How strict should parents be with their children?”

   The old man pointed to(指着)a string (细绳) between a big strong tree and a thin young one.

  “Please untie (解开) that string.” said the old man. “But first pull the string tight so that(以便于)the young tree is straight again.” The young man did so. He untied the string and only found that the young tree bent(弯)over to one side.

  Then the old man said,“There, it is the same with children. You must be strict with them. But sometimes you must untie the string to see how they are getting on. If they are not yet able to stand alone,you must tie the string tight again. But when you find that they are ready to stand alone,you can take the string away.”

小题1:The story is about ____________.

      A. how to take care of young trees    

B. how strict parents should be with their children

C. how the young father should get on with his old neighbor

小题2: The young man untied the string ________________.

      A. in order to throw it away    

B. so that both of the trees wouldn’t grow straight

      C. and found that the young tree bent over to one side

小题3:When could the string be taken away?

      A. When the old man left.     

B. When the young man untied it next time.

     C. When the young tree grew strong enough.

小题4: At last the old man told the young man ________________.

      A. that he should be strict with his children if they could not 

stand alone

      B. that he should always be strict with his children

      C. that he should be hard on his children

小题5:We learn that the big strong tree and the thin young one are like _________.

A. the young father and the old neighbor     

B. parents and their children

       C. the old neighbor and the children of young father

名词解释