题目内容
在远距离输电时,要考虑尽量减少输电线上的功率损失。某电站输送的电功率为P=50KW当使用U=5KV的电压输电时,测得安装输电线路起点和终点处的两只电度表一昼夜的示数相差4800千瓦时。求:
这时的输电效率n和输电线的总电阻r(6分)
要想使输电效率提高到98%,又不改变输电线,那么电站应用多高的电压向外输电?(6分)
这时的输电效率n和输电线的总电阻r(6分)
要想使输电效率提高到98%,又不改变输电线,那么电站应用多高的电压向外输电?(6分)
(1)60% (2)20 (3) 22.4KV
试题分析:(1)由于输送功率为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180336634670.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180336900633.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180337258560.png)
因此效率
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180337555573.png)
(2)输电线上的电流可由
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180337882506.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180338148516.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241803385061074.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180338772564.png)
(3)输电线上损耗功率
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180339084909.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180339396738.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180339708702.png)
计算可得输电电压应调节为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824180339926670.png)
点评:输电线上的损失功率与其电流的平方成正比,而与输电线两端的电压的平方成反比.
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目