问题 单项选择题

某110kV变电站,主变压器电压为110/35/10kV,容量为40MVA,无功补偿用并联电容器装置装设于10kV侧,假定并联电容器补偿容量按主变容量的10%装设,分成两组,电网主谐波为5次及以上,3次谐波不超标,请分析(或计算)回答以下问题。

针对本题情况,选择适合本站电容器组的接线和保护方式( )。

A.双星形接线采用中性点不平衡电流保护;
B.单星形接线采用相电压差动保;
C.单星形接线采用开口三角电压保护;
D.单星形接线采用桥式差电流保护。

答案

参考答案:C

解析: 根据GB 50227-1995第6.1.2条的相关规定,电容器组接线和保护方式共有4种方式,2000kvar为小型电容器组,10kV通常为单串联段。A.电容器组应能分成两个星形,适合容量较大的电容器组;B.适合于每相为两个及以上的串联段的电容器组;C.电容器组的每相要能构成4个桥臂,电压为10kV的小容量电容器组一般不采用这种方式。

阅读理解

阅读理解。

     This story about an old man and a clever monkey is a very old one. Aesop, a Greek writer, first told

the story many years ago. This monkey belonged to an old man. The old man was very fond of the garden,

so when birds came to the garden, he chased them away. He also helped the old man in many other ways.

The old man often fell asleep during the day in his chair. Then the monkey sat at the old man's side and

chased the flies away from the old men's face.

     One hot afternoon in the summer, the old man was asleep in his chair. A fly came and sat on the end

of the old man's nose. The monkey chased it away. Soon the fly came back and sat on the old man's

nose again. The monkey chased it away. This continued for five or six times. The monkey at last became

very angry. He jumped up, ran to the garden, and picked up a large stone. The next time when the fly sat

on the old man's nose, the monkey hit it hard with the stone. He killed the fly, but unfortunately he broke

the old man's nose.

1. This story was first told by a Greek _____. [ ]

A. famous poet

B. great philosopher

C. fable writer

D. well-known physicist

2. When birds came to the garden, the monkey chased them away. The verb "chase" means _____. [ ]

A. drive out

B. get hold of

C. catch up with

D. keep up with

3. The monkey picked up a large stone, because he wanted _____. [ ]

A. to fight to death

B. to put the fly to death

C. to hit the fly on the head

D. to strike the old man on the nose

4. The monkey at last became angry, because _____. [ ]

A. the old man didn't give him anything to eat

B. the old man made the monkey do nothing

C. the old man often fell asleep during the day in his armchair

D. He couldn't drive the fly away

5. Which of the following statements is true according to this passage?[ ]

A. From this story we can learn; sometimes things done out of harmful will may be good.

B. From this story we can learn; sometimes things done out of good will may be good.

C. From this story we can learn; sometimes things done out of harmful will may be harmful.

D. From this story we can learn; sometimes things done out of good will may be harmful.

单项选择题