题目内容
(10分)一居民小区有440户,以前每户平均消耗电功率为100W,使用的区间变压器匝数比为165:6,恰好能使额定电压为220V的用电器正常工作,现在因家用电器增加,每户平均消耗的电功率为250W,若变压器输入电压仍为6600V,区间输电线线路不变,为了使家用电器正常工作,需换用区间变压器,则此变压器的匝数比为多少?
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000716393279.png)
试题分析:未换时输电电流
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000716408768.png)
输电电压
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250007164242029.png)
则由
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000716440670.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000716455724.png)
换变压器后,
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000716471803.png)
线路损失电压
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000716486653.png)
变压器输出电压
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000716502602.png)
所以变压器匝数之比为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000716518655.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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