问题 问答题 简答题

怎样选择电流互感器?

答案

参考答案:

选择电流互感器时应考虑以下内容。

(1)一次频定电流在运行电流的20%~120%的范围内。

(2)电流互感器的一次额定电压和运行电压相同。

(3)注意使二次负载所消耗的功率不超过额定负载。

(4)根据系统的供电方式,选择互感器的台数和满足继电保护方式的要求。

(5)根据测量的目的和保护方式的要求,选择其准确度等级。

多项选择题
阅读理解

阅读理解

     Some people argue that the pressures on international sportsmen and sportswomen kill the spirit of

sport: the pursuit (追求) of personal excellence. Children kick a football around for fun. When they get

older and play for local school teams, they become competitive but they still enjoy playing. The sportsman representing his country cannot afford to think about enjoying himself, he has to think only about winning. He is responsible for an entire nation's hopes and dreams.

   A good example is the football World Cup. Football is the world's most important sport. It is even

more important now that the United States is seriously taking it up. Winning the World Cup is perhaps

eh greatest of international sporting success. Mention " Argentina " to someone and the chances are that

he'll think of football. In a sense, winning the World Cup " put Argentina on the map ".

     Sports fans and supporters get quite irrational about the World Cup. People in England felt that their

country was somehow important after they won the World Cup. Last year thousands of Scots sold their

cars, and even their houses, and spent all their money traveling to Argentina, where the finals were played.

     So am I arguing that international competitions kill the idea of sport? Certainly not! Do the

Argentineans really believe that because eleven of their men proved the most skillful at football, their

nation is better than all others? Not really. But it's nice to know that you won, and that in one way at least

your country is best.

1. What is mainly discussed in this passage is _________.

A. why international sport is necessary

B. what international sport is like

C. how international sport goes on

D. what disadvantages international sport has

2. Those who are against international competitions think that ________.

A. sport should not be so popular

B. sport should not be competitive

C. sport should be for personal purpose

D. sport should be made easier

3. We can infer from the passage that the underlined word " irrational " means_________.

A. against reasonable behavior

B. having much knowledge

C. unable to understand

D. eager to know

4. What does the writer mean by saying that winning the World Cup " put Argentina on the map"_____

A. Argentina has the best football player

B. Argentina has become world-famous for football

C. Football is very popular in Argentina

D. Argentina has begun to pay much attention to football