问题 问答题 简答题

电压互感器的二次回路为什么要接地?

答案

参考答案:

电压互感器一次绕组接于高压系统,如果在运行中,电压互感器的绝缘发生击穿,高电压将窜入二次回路会损坏设备和威胁运行人员的人身安全。因此,为保障二次设备和人身安全,要求电压互感器的二次回路有一点接地,它属于保护接地。

阅读理解

阅读理解。

     After serious earthquake happened. A father left his wife safely at home and rushed to his son's school,

only to find that the building where his son studied had collapsed and looked like a pancake.(煎饼).

    He was shocked (震惊). He didn't know what he should do for a while,then he remembered the words he

had said to his son: "No matter what, I'll always be there for you!"And tears began to fill his eyes. He started

digging through the ruins (废墟).

    As he was digging,other helpless parents and the firemen arrived and tried to pull him off the ruins, saying:

"It's too late! They're all dead! There's nothing you can do!" To them he replied: "Are you going to help me

now?"And then he kept on digging?

    No one helped, however. He went on alone because he needed to know for himself:"Is my boy alive or is

he dead?" He dug for eight hours…12 hours…24 hours…36 hours…then,in the 39th hour,he pulled back a

rock and heard his son's words. He shouted his son's name "ARMAND!"He heard back,"Dad!?! It's me, Dad!

I told the other kids not to worry. I told them that if you were alive, you'd save me and when you saved me,

they'd be saved. You promised (承诺). 'No matter what happens, I'll always be there for you!'You did it,

Dad!"

     "What's going on there? How is it?" the father asked.

     "There are 14 of us left out of 33, Dad. We're frightened, hungry, thirsty and thankful you're here. When

the building fell down, it made a triangle (三角), and it saved us."

    "Come out, boy!"

    "No, Dad! Let the other kids out first,because I know you'll get me! No matter what happens, I know you'll

always be there for me!"

1. The underlined word "collapsed" probably means _______.

A. 倒塌

B. 摇晃

C. 耸立

D. 颠簸

2. Who came to help the father when he digging?

A. His wife

B. Other parents

C. The firemen

D. No one

3. Other parents and the firemen wanted to pull him off the ruins because they thought _______.

A. he was mad

B. all the children had died in the earthquake

C. he was too dangerous to others

D. it was not his job to dig

4. How many students were still alive when the father found them in the ruins?

A. Fourteen

B. Thirty-three

C. Forty-seven

D. Nineteen.

5. We can learn from the passage that _______.

A. It took the father one day to find his son and other students

B. His wife died in the earthquake

C. His son was the last one to come out of the ruins

D. The son didn't believe his father would come to save him

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