问题 问答题 论述题

牵引电动机的绝缘结构主要有几种?

答案

参考答案:

(1)匝问绝缘:是指同一线圈的各个线匝之间的绝缘。

(2)层间绝缘:是指线圈上、下层之间的绝缘。

(3)对地绝缘:是指电机各绕组对机座和其他不带电部件之间的绝缘。

(4)外包绝缘:是指在包在对地绝缘外面的绝缘。

(5)填充及衬垫绝缘:填充绝缘主要用于填充线圈的空隙,使整个线圈牢固地形成一个整体,减少振动,也使线圈成型规矩、平整,以利于包扎对地绝缘,也有利于散热。衬垫绝缘的主要作用是保护绝缘结构在工艺操作时免受机械损伤。

(6)换向器绝缘:换向器绝缘包括换向片片间绝缘和换向片组对地绝缘。换向器的主绝缘是换向片组和压圈间的V形云母环及云母套筒。

阅读理解

Let’s say you have a piece of wood, a nail, and a hammer. Pretend the wood is a person, and the nail is a mean rumor(谣言) about that person. If you hammer in the nail, you’re obviously hurting him or her. If you then pull out the nail, there’s still a hole in the wood, and the damage has been done.

There are many reasons why that nail of a rumor can be so harmful. Rumors are, quite simply, a form of bullying(欺侮). When a person or a group makes up a rumor about someone or decides to spread gossip, it’s usually to hurt someone, break up a friendship, or make someone less popular. It’s the same thing as teasing, only it’s done behind someone’s back instead of to his or her face.

When you spread a rumor about someone, you’re sending a signal that the person is outside of the group, and somehow less worthy of friendship than others. You’re making fun of that person or pointing out negative things about him or her. This can let others think that it’s okay to make the person feel bad, and make him or her an outsider.

We need to be able to trust our friends, and gossip and rumors can break this trust. If you tell a personal secret to a friend, and he turns around and tells it to someone else, you might feel like you will get burned if you ever get close to him again.

Letting a rumor influence your behavior is like letting someone else make a big decision for you. Let’s say you hear that the teacher plans to call a Snow Day tomorrow because a blizzard (暴风雪) is coming. Expecting a day off, you don’t do your homework. The next morning, the blizzard turns out to be nothing more than a drizzle(毛毛雨), and school isn’t off after all. You get zeroes on your work.

小题1:To tell a rumor and a tease apart, you depend on ______.

A.whether it is done behind someone

B.whether it is painful or not

C.whether it is a kind of bullying

D.whether it is spread fast.小题2:If a rumor is spread about someone, others may_______.

A.point out his or her advantages

B.keep away from him or her

C.not feel he or she is an outsider

D.be hurt if getting close to him or her again.小题3:The purpose of this passage is to _______.

A.advise on how to deal with rumors

B.teach us how to judge a rumor

C.find out why rumors spread fast

D.explain why rumors hurt

单项选择题