问题 问答题 简答题

阀控铅酸蓄电池在通信电源供电系统中主要起什么作用?它在运行期间中的故障现象主要有哪些?

答案

参考答案:

蓄电池在通信电源系统中的作用

1)整流设备组合为直流浮充供电系统;

A.通信设备求不间断供电,当交流中断,蓄电池是支持通信系统工作的唯一后备电源,其输出电压应满足通信设备对基础电源的电压范围要求,其供电时间依据市电类别决定;

B.平滑滤波;

C.调节系统电压;

2)在邮电企业中的其他用途:

A.在UPS系统中作后备电源;

B.在动力设备中作启动电源;

阀控铅酸蓄电池在运行期间的主要故障表现是:

1)电池失效:

原因:a、节流阀破坏、氧循环破坏、电池密封不严导致失水;

b、自放电严重、正极板腐蚀引起放电量减少;

c、过放电和环境温度高引起热失控;

2)硫酸盐化:

原因:a、过充电、充电不足、浮充电压低;

b、电解液质量不纯、密度过大、漏液;

3)正极板栅腐蚀:

原因:a、浮充电压高、充电时间长;

b、板栅材料耐腐蚀性能差、自放电大;

4)自放电:

原因:a、铅枝搭桥、隔板孔径过大;

b、电解液有害杂质多;

单项选择题
阅读理解

My six-year-old came home from school this week with two envelopes. One was for a donation to help people in the Philippines. The other was to help hungry families have a Thanksgiving meal.

“I’ll put a check in each of these. Then you can add your own money from your piggy bank, okay?” I said, thinking he’d be so excited to put his own stamp on things.

“That’s okay, mom. You put money in. I don’t want to waste mine,” he sweetly sang as he colored. “I want to fill my bank all the way up.”

Ack! I guess I know what our dinnertime discussion will be about tonight, I thought.

I had figured that through watching his parents donate items, helping us take toys from time to time to needy kids and putting money in the basket at church, he would just understand why it was important to help people in need — and even want to do it himself.

But of course he doesn’t really understand yet. “There’s a big disconnect between the people ‘over there’ and my piggy bank,” said parenting educator Vicki Hoefle.

“There’s nothing wrong with the child. There’s just no connection.”

As for having that conversation immediately, or forcing my son to put money into the envelopes: “Try not to do it now,” Hoefle said. Teaching a child about donating their own money or toys or time to people in need “should be a gentle introduction into what we hope will be a way of life for our kids.”

She suggested these things to help children understand the importance of giving:

* Just talk about it. Then explore the issue from a perspective he can understand.

* Use the course of a year to introduce kids to opportunities. That way, they won’t be shocked when you ask them to stuff their own money into an envelope (like this writer just did).

* Pick a family charity for the year and have a conversation about how you all can help throughout the year.

* Think of this not as something you must teach, but as something to expose them to.

At her house, Hoefle said, “When you got something new, you gave something up.” Each birthday, her children would pick what toys they had outgrown and give them away. “There was a comfort in it. It just became a natural part of the kids’ lives.”

So I will fill those envelopes alone this time. But I’ll make sure he understands why they should be filled—gradually.

小题1:When the writer asked her son to give money to help the poor, he __________.

A.declined to donate

B.sang a sweet song

C.put all his money in a bank

D.seemed very surprised小题2:Hoefle’s attitude towards children’s unwillingness to donate money can be best described as “_______”.

A.critical

B.tolerant

C.positive

D.worried小题3:Which of the following is Hoefle’s approach to educating kids about charity?

A.Giving courses about charity.

B.Setting a rule for children to give.

C.Inviting a lot of poor people home.

D.Giving children enough real life chances.小题4:What can we learn about the writer from the passage?

A.She often makes donations for people in need.

B.She taught her son a lesson over dinner that evening.

C.She is at a loss as for what she should do next.

D.She invited a parenting educator home for advice.小题5:What is the best title of the passage?

A.Kids, please help those in need.

B.Why are kids unwilling to donate?

C.Kindness is lost in the young generation.

D.How can we help kids learn generosity?