天津大学网络教育学院2016年6月电工技术基础（专）答案

奥鹏作业答案

电工技术基础（专）

第一组：

计算题：

一、（24分）电路如图所示，已知file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image004.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image006.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image008.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image010.png。试用支路电流法求各电阻中的电流。

  file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image012.png     

二、（24分）图示电路，已知电源电压file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image014.pngV，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image016.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image018.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image020.png。

(1) 当开关S断开时，求file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image022.png和file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image024.png；

(2) 当开关闭合时，求file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image026.png和file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image024.png。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image028.png

三、（24分）已知星形联结负载，每相复阻抗file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image030.png，接至线电压为380V的对称三相电源，求线电流及负载功率。若将此三相负载改为三角形联结，线电流及负载功率将变成多少？

四、(28分）电路如图所示，其中file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image032.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image034.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image036.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image038.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image040.png。原来S是闭合的，电路达稳态后在file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image042.png时将S打开，试求开关S打开后的电容电压file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image044.png。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image046.png      

第二组：

计算题：

一、（22分）用叠加法求各支路电流。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image048.jpg

二、（22分）如题图电路所示。已知US1 = 72V，US2 = 80V，R1 =1.5k，R2 = 3k，R3 = R4 = 2k，负载电阻RL=1.5k。用戴维南定理求RL中的电流IL。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image050.png  

三、（32分）图示电路中，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image052.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image054.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image056.png，外施电压file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image058.png，试求电流I和电压file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image060.png。

                       file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image062.png

四、（24分）电路如图所示，其中file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image064.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image066.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image068.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image070.png。开关闭合前电路已达稳态，求S闭合后电容电压uC。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image072.png

第三组：

计算题：

一、(16分）用结点电压法求I3。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image074.jpg

二、（30分）正弦稳态电路如图所示，已知电流有效值I=2A，功率P=16W，功率因数file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image076.png（容性），电压U1=10V。求U、R、XL。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image078.png

三、（26分）如图所示电路中，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image080.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image082.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image084.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image086.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image088.png。试求电流file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image090.png的有效值，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image092.png的瞬时值。

                        file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image094.png

四、（28分）电路如图所示，其中file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image096.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image098.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image100.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image102.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image104.png。开关闭合前电路已达稳态，求S闭合后电感电流iL。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image106.png

第四组：

计算题：

一、（19分）用戴维宁定理求I。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image108.jpg

二、（25分）图示RLC串联支路，接至正弦电压源。已知：电路电压file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image110.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image112.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image114.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image116.png。求电路的平均功率P、无功功率Q以及视在功率S。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image118.png

三、（28分）如图所示电路中，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image120.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image122.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image124.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image126.png, file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image128.png，试求电流i的有效值和file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image130.png的瞬时值。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image132.jpg

四、（28分）图示一阶动态电路，已知file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image134.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image136.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image138.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image040.png。原来开关S是闭合的，电路达稳态后将S闭合，求开关S闭合后的file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image141.png。file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image143.png

第五组：

计算题：

一、（18分）用支路电流法求支路电流和各电压源供出功率。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image145.jpg

二、（24分）如图所示正弦稳态电路，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image147.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image149.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image151.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image153.png。求file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image155.png及总有功功率P。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image157.png

三、（30分）在图示电路中，已知file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image159.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image161.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image163.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image165.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image167.png。求电流i的有效值I。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image169.png

四、（28分）图示电路，已知file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image171.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image173.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image175.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image177.png，file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image149.png。原来S是打开的，电路达稳态后将S闭合，试求开关S闭合后的file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image180.png。

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image182.png

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