问题 问答题 简答题

为什么我国规定110kV以上的高压电网和380/220V的低压电网要采用大电流接地系统?各有什么优点?

答案

参考答案:

大电流接地系统发生单相接地时中性点电位仍为零,非故障相对地电压不会升高,仍为相电压,因此电气设备的绝缘水平只需按电网的相电压考虑,故可以降低工程造价。所以我国110kV及以上的电力系统基本上都采用中性点直接接地的方式。而在380/220V系统中采用中性点直接接地方式,主要是考虑人身安全问题,一旦发生单相接地故障,可以迅速跳开自动开关或烧断熔断丝,将故障部分切除。

阅读理解

  Arthur  Miller(1915-2005)is universally  recognized  as one of the greatest dramatists  of the 20th  century. Miller`s father  had  moved to the USA from  Austria Hungary.Drawn like so many other by the“Great American  Dream”However, he experienced severe financial hardship when his family business was ruined in the Great Depression of the  earlv l930s.

Milles's most famous play, Death of a SaIesman, is a powerful attack on the American system.with its aggressive way of doing business and its insistence on money and social status as indicators of worth. In Willy Loman, the hero of the play, we see a man who has got into double with his worth. Willy is “burnt out” and in the cruel world of business there is no room for sentiment : if he can't do the work, then he is no good to his employer, the Wagner Company, and he must go. Willy is painfully aware of this, and at loss as to what to do with his lack of sucess. He refuses to face the fact that he has failed and kills himself in the end.

When it was first staged in 1949 ,the  play was greeted with enthusiastic revews,and it won the Tony Award for Best Play,the New York Drama Critics` Circle Award,and the Pulitzer Prize for Drama.It was the first play to win all three of these major awards.

Millerl died  of hear failure at his home in Roxbury,Connecticut,on the evening of February 10,2005,the 56th anniversary  of the first performance of Death of a Salesman on Broadway.

小题1:

Why did Arthur Miller' s father move to the USA?

A.He suffered from severe hunger in his home country.

B.He was attracted by the "Great American Dream.

C.He hoped to make his son a dramatist.

D.His family business failed.小题2:

The play Death of a Salesman

A.exposes the cruelty of the American business world

B.discusses the ways to get promoted in a company

C.talks about the business career of Arthur Miller

D.focuses on the skills in doing business小题3:

What can we learn about Willy Loman?

A.He treats his employer badly.

B.He runs the Wagner Company.

C.He is a victim of the American system.

D.He is regarded as a hero by his colleagues.小题4:

After it was first staged, Death of a Salesman

A.achieved huge success

B.won the first Tony Award

C.was warmly welcomed by salesmen

D.was severely attacked by dramatists小题5:

What is the text mainly about?

A.Arthur Miller and his family.

B.The awards Arthur Miller won.

C.The hardship Arthur Miller experienced.

D.Arthur Miller and his best-known play.

判断题