题目内容
某电厂要将电能输送到较远的用户,输送的总功率为
,发电机的输出电压仅为350V,为减少输电损失,实行先升压再降压。已知输电线路的总电阻为4
,允许损失5%。用户电压为220V。求升压、降压变压器的原副线圈的匝数比。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132142655.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132189333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132220699.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132267967.png)
依题意画出远距离输电电路如图
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241331322823217.png)
所示:电路损失功率P损=P总5%=I22R线,I2=
=
A=35A,升压变压器输出电压为U2=P总/I2=
V=2.8×103V。据理想变压器原理得,升压变压器的初、次级的匝数比为
=
=
=
,降压变压器的输入功率为:P3=P总-P损=P总-5%P总=95%P2=95%×9.8×104W=9.31×104W。降压变压器的初级电压为:U3=
=
V=2660V。所以降压变压器的匝数比为:
=
=
=12.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241331322823217.png)
所示:电路损失功率P损=P总5%=I22R线,I2=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132313714.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132345895.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132376704.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132423411.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132454406.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132485729.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132516352.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132547477.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132672682.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132703437.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132735455.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133132766579.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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