问题 问答题 简答题

为什么500kV线路并联电抗器要装设匝间保护?

答案

参考答案:

并联电抗器的匝间短路有两种情况:一种是伴随有接地故障的匝间短路.此时往往由反映接地故障的保护动作.断开电抗器的供电回路;另一种是不伴随接地的纯匝间短路。此时,短路匝与每相电抗器的总匝数之间的关系如同一台二次侧短路的自耦变压器,一、二次之间的匝数比很大.短路电流也很大.但反映到高压线端TA的电流变化却不大.这使得反映电气量的继电器很难检测匝间短路:因此,有必要装设匝间保护。

阅读理解

It is time for students to sell such things as chocolate bars and greeting cards to raise money for their school, class or club.It is inevitable that they will knock on your door and you will easily hand over your cash for overpriced items that you really do not want.That is okay, though, because there are many reasons why children should be allowed to raise money for their schools and clubs.

Fundraising is a great way to help children learn social skills.It is not easy to go up to a complete stranger and ask him for his money.They have to nicely ask for help, show the interested buyer what they have to offer and explain how it will help them in school.If someone refuses to buy an item, that child has to take the failure in stride(不特别费力地), and that is a learning lesson as well.

Students can learn how to deal with money by fundraising.Of course, it might seem safer for us to take charge of our children’s earnings from their fundraising before it is turned into the school.However, by making them keep track of it, count it, and make sure everyone pays the right amount, they are learning an important lesson.Dealing with more Fundraising helps improve their schools.It is the children’s school.They have to learn there and grow there.Why not let them help in making it a better place?

Fundraising allows for more life experiences for the child.The raised money is used towards things like parties, trips, or for the music club to go to see a Broadway play.The children receive the rewards for their hard work at raising the money.Without fundraising, these field trips and special school memories would be missed.

In a word, fundraising helps children a lot in many ways.

小题1:The underlined word “inevitable” in the first paragraph means “_______”.

A.unlikely

B.improper

C.unavoidable

D.unrealistic小题2:One of the important indications that children are grown up is that __________.

A.children learn to care for others

B.children can deal with money

C.children like to make up

D.children make a date with friends of the other sex小题3:The author thinks that fundraising _______.

A.adds to the family’s burden

B.wastes the learning time

C.builds up the children’s bodies

D.helps to develop the children’s character小题4:Which of the following shows the structure of the passage?

CP: Central point   P: Point      Sp: Sub-point     C: Conclusion

判断题