问题 问答题 简答题

电机内部电晕现象是什么原因造成的?

答案

参考答案:

在带电导体的光角处由于电线密集电场不均匀局部过强使附近的空气发生游离在围绕尖角处放电形成兰色光圈称为电晕发电机。电晕产生大多由于:

(1)线棒的出槽口处,该处线棒与边端铁心间有电力线集中,它们好像一个电容器,线棒导体和边端铁心相当于电容器的两个极板,线棒绝缘和空气相当于电容器极板的介质,两极间有很强的电场;

(2)线棒绝缘表面与定子在强电场的作用下空气易游离而产生电晕;

(3)定子铁心通风沟处因电力线密集于硅钢片边缘上,将产生放电尖角。

阅读理解

阅读理解。

     My father is tall and has short, gray (灰白的) hair. He wears glasses with heavy, black frames

(框架). But I just see a picture of him from 1968. What a surprise! In the picture, he's 15 years old.

He's short and he has glasses with small, round frames. He has long, yellow hair and it's really straight.

He's wearing blue jeans and a T-shirt with the word "Love". I'm 15 years old now. I'm medium height

and I have short hair. My hair isn't yellow, it's blue. My dad thinks it's strange (奇怪的), but my friends

think it's great. I wear glasses, but my glasses have bright red frames. They're so cool! I have an

earring (耳环) in one ear, too. Dad really can't understand (明白) that, I never wear blue jeans. I like

big, baggy (松的) pants and long T-shirts. Most of my T-shirts have pictures of my favorite rock

bands (摇滚乐队) on them.

1. What kind of glasses does my father wear when he is fifteen years old?   He wears _______.

A. glasses with heavy, black frames    

B. glasses with bright red frames

C. long and yellow glasses          

D. glasses with small, round frames

2. What color is my hair? It's _______. 

A. yellow            

B. blue           

C. gray        

D. red

3. What do I like to wear? I like to wear _______.

A. blue jeans and a T-shirt

B. yellow jeans and a T-shirt with the word "love"

C. big and baggy pants and long T-shirts

D. blue jeans and an earring

4. What's on my father's T-shirt?

A. The word "love".

B. Heavy and black frames.

C. Pictures of rock bands.

D. An earring.

5. Who has an earring in one ear?

A. My dad does.    

B. I do.        

C. My father does.    

D. My Friends do.

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