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</gourl2><NodeID>25</NodeID><Title>高压输电</Title><SoftSize>0.00</SoftSize><SoftSizeUnit>B</SoftSizeUnit><SoftSize>0.00</SoftSize><SoftSizeUnit>B</SoftSizeUnit><typeicon>other</typeicon><editor>czwlzx</editor><author>王宗田</author><user>czwlzx</user><userface>/UploadFiles/UserPic/UserAvatars/15219_150_150.jpg</userface><Hits>
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   </Stars><Author>王宗田</Author><infopoint>0</infopoint><Keyword>高压,输电</Keyword><CopyFrom>本站原创</CopyFrom><SoftType></SoftType><CopyrightType></CopyrightType><DecompressPassword></DecompressPassword><OperatingSystem></OperatingSystem><UpdateTime>2004年12月10日</UpdateTime><RegUrl></RegUrl><DemoUrl /><DefaultPicUrl>/UploadFiles/ckzlzx_UploadFiles_2200/200412109470371.jpg</DefaultPicUrl><Intro>从发电站发出的电能，一般都要通过输电线路送到各个用电地方。根据输送电能距离的远近，采用不同的高电压。</Intro><SoftIntro2>从发电站发出的电能，一般都要通过输电线路送到各个用电地方。根据输送电能距离的远近，采用不同的高电压。从我国现在的电力情况来看，送电距离在200～300公里时采用220千伏的电压输电；在100公里左右时采用110千伏；50公里左右采用35千伏；在15公里～20公里时采用10千伏，有的则用6600伏。输电电压在110千伏以上的线路，称为超高压输电线路。在远距离送电时，我国还有500千伏的超高压输电线路。 
　　为什么要采用高压输电呢？这要从输电线路上损耗的电功率谈起，当电流通过导线时，就会有一部分电能变为热能而损耗掉了。我国目前普遍采用的三相三线制交流输电线路上损耗的电功率为
P耗＝3I2R
式中的R为每一条输电线的电阻，I为输电线中的电</SoftIntro2><SoftIntro>
    【内容简介】从发电站发出的电能，一般都要通过输电线路送到各个用电地方。根据输送电能距离的远近，采用不同的高电压。从我国现在的电力情况来看，送电距离在200～300公里时采用220千伏的电压输电；在100公里左右时采用110千伏；50公里左右采用35千伏；在15公里～20公里时采用10千伏，有的则用6600伏。输电电压在110千伏以上的线路，称为超高压输电线路。在远距离送电时，我国还有500千伏的超高压输电线路。 
　　为什么要采用高压输电呢？这要从输电线路上损耗的电功率谈起，当电流通过导线时，就会有一部分电能变为热能而损耗掉了。我国目前普遍采用的三相三线制交流输电线路上损耗的电功率为
P耗＝3I2R
式中的R为每一条输电线的电阻，I为输电线中的电流。如果要输送的电功率为P，输电线路的线电压为U，每相负载的功率因数为 则输电电流还可表示为

　　假设送电距离为L，所用输电线的电阻率为ρ，其截面积为S，则R＝ρ（L／S）。于是，损耗的电功率可写成

式中。在输送的电功率、输电距离、输电导线材料
　　及负载功率因数都一定的情况下，C为一常数。
　　由上式可以看出，输电线截面积S一定时，输电电压U愈高，损耗的电功率P耗就愈小；如果允许损耗的电功率P耗</SP</SoftIntro><SoftIntroEncode>从发电站发出的电能，一般都要通过输电线路送到各个用电地方。根据输送电能距离的远近，采用不同的高电压。从我国现在的电力情况来看，送电距离在200～300公里时</SoftIntroEncode><special /><DownloadUrl></DownloadUrl><Content>&lt;P&gt;从发电站发出的电能，一般都要通过输电线路送到各个用电地方。根据输送电能距离的远近，采用不同的高电压。从我国现在的电力情况来看，送电距离在&lt;SPAN lang=EN-US&gt;200&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;～&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;300&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;公里时采用&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;220&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;千伏的电压输电；在&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;100&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;公里左右时采用&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;110&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;千伏；&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;50&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;公里左右采用&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;35&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;千伏；在&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;15&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;公里～&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;20&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;公里时采用&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;10&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;千伏，有的则用&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;6600&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;伏。输电电压在&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;110&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;千伏以上的线路，称为超高压输电线路。在远距离送电时，我国还有&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;500&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;千伏的超高压输电线路。&lt;/SPAN&gt; 
&lt;P class=MsoNormal&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;　　为什么要采用高压输电呢？这要从输电线路上损耗的电功率谈起，当电流通过导线时，就会有一部分电能变为热能而损耗掉了。我国目前普遍采用的三相三线制交流输电线路上损耗的电功率为&lt;/SPAN&gt;&lt;/P&gt;
&lt;P class=MsoNormal style="TEXT-ALIGN: center" align=center&gt;&lt;SPAN lang=EN-US&gt;P&lt;/SPAN&gt;&lt;SUB&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 10.5pt"&gt;耗&lt;/SPAN&gt;&lt;/SUB&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;＝&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;3I&lt;/SPAN&gt;&lt;SUP&gt;&lt;SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"&gt;2&lt;/SPAN&gt;&lt;/SUP&gt;&lt;SPAN lang=EN-US&gt;R&lt;/SPAN&gt;&lt;/P&gt;
&lt;P class=MsoNormal style="TEXT-INDENT: 21pt; mso-char-indent-count: 2.0; mso-char-indent-size: 10.5pt"&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;式中的&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;R&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;为每一条输电线的电阻，&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;I&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;为输电线中的电流。如果要输送的电功率为&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;P&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;，输电线路的线电压为&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;U&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;，每相负载的功率因数为&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;&lt;SUB&gt;&lt;?xml:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" /&gt;&lt;v:shapetype id=_x0000_t75 coordsize="21600,21600" o:spt="75" o:preferrelative="t" path="m@4@5l@4@11@9@11@9@5xe" filled="f" stroked="f"&gt; &lt;IMG alt="" hspace=0 src="PE.SiteConfig.ApplicationPathPE.SiteConfig.uploaddir/ckzlzx_UploadFiles_2200/200412109470734.gif" align=baseline border=0&gt;&lt;/v:shapetype&gt;&lt;/SUB&gt;&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;则输电电流还可表示为&lt;/SPAN&gt;&lt;/P&gt;
&lt;P class=MsoNormal style="TEXT-INDENT: 21pt; TEXT-ALIGN: center; mso-char-indent-count: 2.0; mso-char-indent-size: 10.5pt" align=center&gt;&lt;IMG alt="" hspace=0 src="PE.SiteConfig.ApplicationPathPE.SiteConfig.uploaddir/ckzlzx_UploadFiles_2200/200412109470580.gif" align=baseline border=0&gt;&lt;/P&gt;
&lt;P class=MsoNormal&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;　　假设送电距离为&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;L&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;，所用输电线的电阻率为ρ，其截面积为&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;S&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;，则&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;R&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;＝ρ（&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;L&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;／&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;S&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;）。于是，损耗的电功率可写成&lt;/SPAN&gt;&lt;/P&gt;
&lt;P class=MsoNormal style="TEXT-ALIGN: center" align=center&gt;&lt;IMG alt="" hspace=0 src="PE.SiteConfig.ApplicationPathPE.SiteConfig.uploaddir/ckzlzx_UploadFiles_2200/200412109470621.gif" align=baseline border=0&gt;&lt;/P&gt;
&lt;P class=MsoNormal style="TEXT-INDENT: 21pt; mso-char-indent-count: 2.0; mso-char-indent-size: 10.5pt"&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;式中&lt;IMG alt="" hspace=0 src="PE.SiteConfig.ApplicationPathPE.SiteConfig.uploaddir/ckzlzx_UploadFiles_2200/200412109470360.gif" align=baseline border=0&gt;&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;。在输送的电功率、输电距离、输电导线材料&lt;/SPAN&gt;&lt;/P&gt;
&lt;P class=MsoNormal&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;　　及负载功率因数都一定的情况下，&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;C&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;为一常数。&lt;/SPAN&gt;&lt;/P&gt;
&lt;P class=MsoNormal&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;　　由上式可以看出，输电线截面积&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;S&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;一定时，输电电压&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;U&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;愈高，损耗的电功率&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;P&lt;/SPAN&gt;&lt;SUB&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 10.5pt"&gt;耗&lt;/SPAN&gt;&lt;/SUB&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;就愈小；如果允许损耗的电功率&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;P&lt;/SPAN&gt;&lt;SUB&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 10.5pt"&gt;耗&lt;/SP</Content><banben></banben><area></area><type></type><type2>不限</type2><ico></ico><video>&lt;P&gt;从发电站发出的电能，一般都要通过输电线路送到各个用电地方。根据输送电能距离的远近，采用不同的高电压。从我国现在的电力情况来看，送电距离在&lt;SPAN lang=EN-US&gt;200&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;～&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;300&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;公里时采用&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;220&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;千伏的电压输电；在&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;100&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;公里左右时采用&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;110&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;千伏；&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;50&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;公里左右采用&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;35&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;千伏；在&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;15&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;公里～&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;20&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;公里时采用&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;10&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;千伏，有的则用&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;6600&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;伏。输电电压在&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;110&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;千伏以上的线路，称为超高压输电线路。在远距离送电时，我国还有&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;500&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;千伏的超高压输电线路。&lt;/SPAN&gt; 
&lt;P class=MsoNormal&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;　　为什么要采用高压输电呢？这要从输电线路上损耗的电功率谈起，当电流通过导线时，就会有一部分电能变为热能而损耗掉了。我国目前普遍采用的三相三线制交流输电线路上损耗的电功率为&lt;/SPAN&gt;&lt;/P&gt;
&lt;P class=MsoNormal style="TEXT-ALIGN: center" align=center&gt;&lt;SPAN lang=EN-US&gt;P&lt;/SPAN&gt;&lt;SUB&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 10.5pt"&gt;耗&lt;/SPAN&gt;&lt;/SUB&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;＝&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;3I&lt;/SPAN&gt;&lt;SUP&gt;&lt;SPAN lang=EN-US style="mso-bidi-font-size: 10.5pt"&gt;2&lt;/SPAN&gt;&lt;/SUP&gt;&lt;SPAN lang=EN-US&gt;R&lt;/SPAN&gt;&lt;/P&gt;
&lt;P class=MsoNormal style="TEXT-INDENT: 21pt; mso-char-indent-count: 2.0; mso-char-indent-size: 10.5pt"&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;式中的&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;R&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;为每一条输电线的电阻，&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;I&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;为输电线中的电流。如果要输送的电功率为&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;P&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;，输电线路的线电压为&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;U&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;，每相负载的功率因数为&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;&lt;SUB&gt;&lt;?xml:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" /&gt;&lt;v:shapetype id=_x0000_t75 coordsize="21600,21600" o:spt="75" o:preferrelative="t" path="m@4@5l@4@11@9@11@9@5xe" filled="f" stroked="f"&gt; &lt;IMG alt="" hspace=0 src="PE.SiteConfig.ApplicationPathPE.SiteConfig.uploaddir/ckzlzx_UploadFiles_2200/200412109470734.gif" align=baseline border=0&gt;&lt;/v:shapetype&gt;&lt;/SUB&gt;&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;则输电电流还可表示为&lt;/SPAN&gt;&lt;/P&gt;
&lt;P class=MsoNormal style="TEXT-INDENT: 21pt; TEXT-ALIGN: center; mso-char-indent-count: 2.0; mso-char-indent-size: 10.5pt" align=center&gt;&lt;IMG alt="" hspace=0 src="PE.SiteConfig.ApplicationPathPE.SiteConfig.uploaddir/ckzlzx_UploadFiles_2200/200412109470580.gif" align=baseline border=0&gt;&lt;/P&gt;
&lt;P class=MsoNormal&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;　　假设送电距离为&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;L&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;，所用输电线的电阻率为ρ，其截面积为&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;S&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;，则&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;R&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;＝ρ（&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;L&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;／&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;S&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;）。于是，损耗的电功率可写成&lt;/SPAN&gt;&lt;/P&gt;
&lt;P class=MsoNormal style="TEXT-ALIGN: center" align=center&gt;&lt;IMG alt="" hspace=0 src="PE.SiteConfig.ApplicationPathPE.SiteConfig.uploaddir/ckzlzx_UploadFiles_2200/200412109470621.gif" align=baseline border=0&gt;&lt;/P&gt;
&lt;P class=MsoNormal style="TEXT-INDENT: 21pt; mso-char-indent-count: 2.0; mso-char-indent-size: 10.5pt"&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;式中&lt;IMG alt="" hspace=0 src="PE.SiteConfig.ApplicationPathPE.SiteConfig.uploaddir/ckzlzx_UploadFiles_2200/200412109470360.gif" align=baseline border=0&gt;&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;。在输送的电功率、输电距离、输电导线材料&lt;/SPAN&gt;&lt;/P&gt;
&lt;P class=MsoNormal&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;　　及负载功率因数都一定的情况下，&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;C&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;为一常数。&lt;/SPAN&gt;&lt;/P&gt;
&lt;P class=MsoNormal&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;　　由上式可以看出，输电线截面积&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;S&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;一定时，输电电压&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;U&lt;/SPAN&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;愈高，损耗的电功率&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;P&lt;/SPAN&gt;&lt;SUB&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 10.5pt"&gt;耗&lt;/SPAN&gt;&lt;/SUB&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"&gt;就愈小；如果允许损耗的电功率&lt;/SPAN&gt;&lt;SPAN lang=EN-US&gt;P&lt;/SPAN&gt;&lt;SUB&gt;&lt;SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-size: 10.5pt"&gt;耗&lt;/SP</video><DefaultPicUrl>
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