问题 问答题 简答题

绝缘油在变压器中的作用?并分别说明。

答案

参考答案:

1、绝缘。变压器油要保证绕组与绕组之间、绕组与接地的铁芯和箱壳之间有良好的绝缘,在额定电压和一定幅值的过电压下,绝缘不击穿;

2、冷却。通过绝缘油的循环将绕组和铁芯产生的热量传递给冷却装置;

3、灭弧。当变压器内部绕组匝间短路或有低能放电产生电弧时,绝缘油剧烈分解成气体,该气体中氢气占70%左右,能迅速降低弧柱温度;

4、浸渍。变压器绕组经油浸渍后,可防止潮气进入,同时可使绕组间残留的气泡被排除,防止运行中产生局部放电,提高绝缘水平。

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阅读理解

     Motorists who used to listen to the radio or their favorite tunes on CDs may have a new way to

entertain themselves, after engineers in Japan developed a musical road surface.

     A team from the Hokkaido Industrial Research Institute has built a number of "melody roads", which

use cars as tuning forks(音叉)to play music as they travel.

     The concept works by using grooves(凹槽). They are cut at very specific intervals in the road

surface. The melody road uses the spaces between to create different notes.

     Depending on how far apart the grooves are, a car moving over them will produce a series of high

or low notes, and designers are able to create a distinct tune.

     Patent documents for the design describe it as notches(刻痕) "formed in a road surface so as to

play a melody without producing simple sound or rhythm and reproduce melodylike tones".

     There are three musical strips in central and northern Japan-one of which plays the tune of a

Japanese pop song. Reports say the system was invented by Shizuo Shinoda. He scraped some

markings into a road with a bulldozer(推土机)before driving over them and found that they helped to

produce all kinds of tones.

     The optimal speed for melody road is 44 kph, but people say it is not always easy to get the

intended sound.

     "You need to keep the car windows closed to hear well," wrote one Japanese blogger. "Driving too

fast will sound like playing fast forward, while driving around 12 mph[20 km/h]has a slowmotion effect,

making you almost carsick."

1. According to the passage, melody roads use________to create different notes.

A. cars  

B. grooves

C. spaces between intervals  

D. bulldozers

2. We can learn from the passage that the highness of notes is depended on________.

A. how far the grooves are

B. how big the grooves are

C. the number of the grooves

D. the speed of the car

3. The underlined word "optimal" in the passage might mean________.

A. fastest  

B. possible

C. best  

D. suitable

4. In order to hear the music well, you have to________.

A. drive very fast

B. drive slowly

C. open the windows wide

D. keep the windows closed

5. What's the best title of the passage?

A. A New Type of Music

B. Melody Roads in Japan

C. A Musical Road Surface

D. A New Invention in Japan