重磅推出：全国注册电气案例题真题披露及解答过程

keast

<DIV class=quote>以下是引用 <B>asi</B></FONT> 在(<I>2008-2-1 15:31:00</I>)的发言<BR>
<P><FONT face=华文新魏 color=#0000ff size=5>虽然我现在没资格考试</FONT></P>
<P><FONT face=华文新魏 color=#0000ff size=5>但仍然严重希望“老版”给大家好好说说备考经验</FONT></P></DIV><BR><BR>没有什么经验，就做了些真题，看了一下《工业与民用配电设计手册》第三版。还有，规范要比较熟悉，这可以确保案例考试第一天100%通过。

keast

<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>6．已知污水处理厂10kV电源中性点经消弧线圈接地，请问电缆绝缘水平最经济合理应取多少，说明原因 <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>A. 6／10KV   B. 10/10KV   C. 8.7/10KV   D. 6.3/10KV <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><o:p> </o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 17.95pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none; mso-char-indent-count: 1.71" align=left>根据&lt;&lt;工业与民用配电设计手册（第三版）&gt;&gt;第九章第一节三(P481)、电力电缆绝缘水平选择<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 17.95pt; mso-layout-grid-align: none; mso-char-indent-count: 1.71">“(1)电缆设计用缆芯对地(与绝缘屏蔽层或金属护套之间)的额定电压U<SUB>o</SUB>，应满足所在电力系统中性点接地方式及其运行要求的水平。中性点非有效接地(包括中性点不接地和经消弧线圈接地)系统中的单相接地故障持续时间在1min到2h之间，必须选用第Ⅱ类的U<SUB>o</SUB>。仅当系统中的单相接地故障能很快切除，在任何情况下故障持续时间不超过1min时，才可选用第Ⅰ类的U<SUB>o</SUB>。一般情况下，220/380V系统只选用第Ⅰ类的U<SUB>o</SUB>，3～35kV系统应选用第Ⅱ类的U<SUB>o</SUB>。” 的规定<o:p></o:p></P>

keast

接上一道题：
<P style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify; mso-pagination: none">《电力工程电缆设计规范(GB 50217-94)》<o:p></o:p></P>
<P style="MARGIN: 0cm 0cm 0pt; mso-pagination: none"><st1:chsdate w:st="on" IsROCDate="False" IsLunarDate="False" Day="30" Month="12" Year="1899">3.3.2</st1:chsdate> 交流系统中电力电缆缆芯与绝缘屏蔽或金属套之间额定电压的选择，应符合下列规定：<o:p></o:p></P>
<P style="MARGIN: 0cm 0cm 0pt; mso-pagination: none">（1）中性点直接接地或经低阻抗接地的系统当接地保护动作不超过1min切除故障时，应按100%的使用回路工作相电压。<o:p></o:p></P>
<P style="MARGIN: 0cm 0cm 0pt; mso-pagination: none">（2）对于（1）项外的供电系统，不宜低于133%的使用回路工作相电压；在单相接地故障可能持续8h以上，或发电机回路等安全性要求较高的情况，宜采取173%的使用回路工作相电压。<o:p></o:p></P>
<P style="MARGIN: 0cm 0cm 0pt; mso-pagination: none"><st1:chsdate w:st="on" IsROCDate="False" IsLunarDate="False" Day="30" Month="12" Year="1899">3.3.3</st1:chsdate> 交流系统中电缆的冲击耐压水平，应满足系统绝缘配合要求。<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><o:p> </o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>参考答案：C <o:p></o:p></P>

keast

<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>7. 10kV中性点经消弧线圈接地，缆芯对地的雷电冲击耐受电压峰值要求为下列何值，说明原因。 <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>A. 60kV   B. 75kV  C. 80kV   D. 95kV <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><o:p> </o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 17.95pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none; mso-char-indent-count: 1.71" align=left>根据&lt;&lt;工业与民用配电设计手册（第三版）&gt;&gt;第九章第一节三(P481)、电力电缆绝缘水平选择<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 17.95pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none; mso-char-indent-count: 1.71" align=left>表9－2选择缆芯对地的雷电冲击耐受电压峰值U<SUB>P</SUB><o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><o:p> </o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; mso-layout-grid-align: none">     表9-2                        电缆绝缘水平选择             单位：kV<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; mso-layout-grid-align: none"><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"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect"></v:path><o:lock v:ext="edit" aspectratio="t"></o:lock></v:shapetype><v:shape id=_x0000_i1025 style="WIDTH: 404.25pt; HEIGHT: 159.75pt" type="#_x0000_t75" o:ole="" fillcolor="window"><v:imagedata src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image001.wmz" o:title=""></v:imagedata></v:shape><o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><o:p> </o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>参考答案：D <o:p></o:p></P>

keast

<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>8.某企业变电所，进线电压35kV，经降压变压器后，以10kV向厂区高压电气设备及用户供电，再经10/0.4kV配电变压器向附近低压用户供电。 <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>(1)现已知10kV系统全部以电缆馈电，其中截面<st1:chmetcnv UnitName="mm" SourceValue="95" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">95mm</st1:chmetcnv><SUP>2</SUP>的电流纵长<st1:chmetcnv UnitName="km" SourceValue="15" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">15km</st1:chmetcnv>，截面<st1:chmetcnv UnitName="mm" SourceValue="120" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">120mm</st1:chmetcnv><SUP>2</SUP>的长<st1:chmetcnv UnitName="km" SourceValue="10" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">10km</st1:chmetcnv>，试计算10kV系统单相接地电容电流最接近下列那些数值： <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>A. <st1:chmetcnv UnitName="a" SourceValue="21" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">21A</st1:chmetcnv>   B. <st1:chmetcnv UnitName="a" SourceValue="27" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">27A</st1:chmetcnv>   C. <st1:chmetcnv UnitName="a" SourceValue="30" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">30A</st1:chmetcnv>  D. <st1:chmetcnv UnitName="a" SourceValue="35" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">35A</st1:chmetcnv> <o:p></o:p></P>
<P class=MsoBodyText style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 18pt; LINE-HEIGHT: normal; mso-layout-grid-align: none">查&lt;&lt;工业与民用配电设计手册（第三版）&gt;&gt;第四章第四节(P152) “八、（1）单相接地电容电流的计算”中的表4－20及表4－<st1:chmetcnv UnitName="’" SourceValue="20" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">20’</st1:chmetcnv>，电缆每千米单相接地电容电流的平均值：<st1:chmetcnv UnitName="mm" SourceValue="95" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">95mm</st1:chmetcnv><SUP>2</SUP>为<st1:chmetcnv UnitName="a" SourceValue="1" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">1.0A</st1:chmetcnv>/km；<st1:chmetcnv UnitName="mm" SourceValue="120" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">120mm</st1:chmetcnv><SUP>2</SUP>为<st1:chmetcnv UnitName="a" SourceValue="1.1" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">1.1A</st1:chmetcnv>/km。变电所增加的接地电容电流值10kV为16％。<o:p></o:p></P>
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<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 8pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center><o:p> </o:p></P></DIV></TD></TR></TABLE><o:p> </o:p></P><BR style="mso-ignore: vglayout" clear=all>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><st1:chmetcnv UnitName="a" SourceValue="1" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">1.0A</st1:chmetcnv>/km×<st1:chmetcnv UnitName="km" SourceValue="15" HasSpace="True" Negative="False" NumberType="1" TCSC="0" w:st="on">15 km</st1:chmetcnv>＋<st1:chmetcnv UnitName="a" SourceValue="1.1" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">1.1A</st1:chmetcnv>/km×<st1:chmetcnv UnitName="km" SourceValue="10" HasSpace="True" Negative="False" NumberType="1" TCSC="0" w:st="on">10 km</st1:chmetcnv>＝<st1:chmetcnv UnitName="a" SourceValue="26" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">26A</st1:chmetcnv><o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><st1:chmetcnv UnitName="a" SourceValue="26" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">26A</st1:chmetcnv>×（1＋0.16）=<st1:chmetcnv UnitName="a" SourceValue="30.16" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">30.16A</st1:chmetcnv><o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><o:p> </o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>用公式的计算<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>10kV系统单相接地电容电流<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"> <v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect"></v:path><o:lock v:ext="edit" aspectratio="t"></o:lock></v:shapetype><v:shape id=_x0000_i1025 style="WIDTH: 156pt; HEIGHT: 18pt" type="#_x0000_t75" o:ole=""><v:imagedata src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image001.wmz" o:title=""></v:imagedata></v:shape>A<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>变电所增加接地电容电流16％，总接地电容电流<v:shape id=_x0000_i1026 style="WIDTH: 111.75pt; HEIGHT: 15.75pt" type="#_x0000_t75" o:ole=""> <v:imagedata src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image003.wmz" o:title=""></v:imagedata></v:shape>A<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>参考答案：C <o:p></o:p></P>

lawwen

K版真是重量级牛人，我们要向他学习啊

冷若冰

所以了，估计以后我们就要称呼K斑：老板。。。。。

keast

接上面一题第二小问：
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>(2)假设上述系统单相接地电容电流计算值为<st1:chmetcnv UnitName="a" SourceValue="32" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">32A</st1:chmetcnv>，若需在接地故障下运行时，试分析10kV系统选择下列那种中性点接地方式最合适，请说明原因 <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>A 不接地   B 直接接地   C 高阻抗接地   D 消弧线圈接地 <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><o:p> </o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 17.95pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none; mso-char-indent-count: 1.71" align=left><STRONG>答：</STRONG>根据《交流电气装置的过电压保护和绝缘配合（DL/T620-1997）》第<st1:chsdate w:st="on" IsROCDate="False" IsLunarDate="False" Day="30" Month="12" Year="1899">3.1.2</st1:chsdate> 条 “3kV～10kV不直接连接发电机的系统和35kV、66kV系统，当单相接地故障电容电流不超过下列数值时，应采用不接地方式；当超过下列数值又需在接地故障条件下运行时，应采用消弧线圈接地方式：<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; mso-layout-grid-align: none">    a)3kV～10kV钢筋混凝土或金属杆塔的架空线路构成的系统和所有35kV、66kV系统，<st1:chmetcnv UnitName="a" SourceValue="10" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">10A</st1:chmetcnv>。<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; mso-layout-grid-align: none">    b)3kV～10kV非钢筋混凝土或非金属杆塔的架空线路构成的系统，当电压为：<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; mso-layout-grid-align: none">    1)3kV和6kV时，<st1:chmetcnv UnitName="a" SourceValue="30" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">30A</st1:chmetcnv>；<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; mso-layout-grid-align: none">    2)10kV时，<st1:chmetcnv UnitName="a" SourceValue="20" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">20A</st1:chmetcnv>。<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; mso-layout-grid-align: none">    c)3kV～10kV电缆线路构成的系统，<st1:chmetcnv UnitName="a" SourceValue="30" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">30A</st1:chmetcnv>。”的规定<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>参考答案：D <o:p></o:p></P>

keast

<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>(3)上述变电所接地网如5-1所示，如果土地电阻率ρ＝30000Ω.cm，估算该接地网工频接地电阻最接近下列哪值 <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>A R=265Ω   B R=3Ω   C R=9Ω   D R=300Ω <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><o:p> </o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=center><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"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect"></v:path><o:lock v:ext="edit" aspectratio="t"></o:lock></v:shapetype><v:shape id=_x0000_i1025 style="WIDTH: 144.75pt; HEIGHT: 84pt" type="#_x0000_t75"><v:imagedata src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image001.emz" o:title=""></v:imagedata></v:shape><o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=center><o:p> </o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 17.95pt; mso-layout-grid-align: none; mso-char-indent-count: 1.71">查《交流电气装置的接地（DL/T621-1997）》附 录A人工接地极工频接地电阻的计算，<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 17.95pt; mso-layout-grid-align: none; mso-char-indent-count: 1.71">A4  人工接地极工频接地电阻的简易计算，可采用表A2所列公式。<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center>表A2  人工接地极工频接地电阻(Ω)简易计算式<o:p></o:p></P>
<DIV align=center>
<TABLE class=MsoNormalTable style="BORDER-RIGHT: medium none; BORDER-TOP: medium none; BORDER-LEFT: medium none; BORDER-BOTTOM: medium none; BORDER-COLLAPSE: collapse; mso-border-alt: solid windowtext .5pt; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt" cellSpacing=0 cellPadding=0 border=1>

<TR style="HEIGHT: 11pt; mso-yfti-irow: 0; mso-yfti-firstrow: yes">
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 1pt solid; WIDTH: 167.4pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 11pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt" width=223>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center>接  地  极  型  式<o:p></o:p></P></TD>
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 1pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #d4d0c8; WIDTH: 352pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 11pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt" width=469>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center>简  易  计  算  式<o:p></o:p></P></TD></TR>
<TR style="HEIGHT: 11pt; mso-yfti-irow: 1">
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #d4d0c8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 1pt solid; WIDTH: 167.4pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 11pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=223>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center>垂  直  式<o:p></o:p></P></TD>
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #d4d0c8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #d4d0c8; WIDTH: 352pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 11pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=469>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center><I style="mso-bidi-font-style: normal">R</I> ≈0.3 ρ<o:p></o:p></P></TD></TR>
<TR style="HEIGHT: 11pt; mso-yfti-irow: 2">
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #d4d0c8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 1pt solid; WIDTH: 167.4pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 11pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=223>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center>单根水平式<o:p></o:p></P></TD>
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #d4d0c8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #d4d0c8; WIDTH: 352pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 11pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=469>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center><I style="mso-bidi-font-style: normal">R</I> ≈0.03 ρ<o:p></o:p></P></TD></TR>
<TR style="HEIGHT: 11pt; mso-yfti-irow: 3">
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #d4d0c8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 1pt solid; WIDTH: 167.4pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 11pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=223>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center>复  合  式<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center>(接地网)<o:p></o:p></P></TD>
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #d4d0c8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: #d4d0c8; WIDTH: 352pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 11pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=469>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center><v:shape id=_x0000_i1026 style="WIDTH: 126.75pt; HEIGHT: 35.25pt" type="#_x0000_t75" o:ole=""><v:imagedata src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image003.wmz" o:title=""></v:imagedata></v:shape><o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center>或<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: center; mso-layout-grid-align: none" align=center><v:shape id=_x0000_i1027 style="WIDTH: 168.75pt; HEIGHT: 38.25pt" type="#_x0000_t75" o:ole=""><v:imagedata src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image005.wmz" o:title=""></v:imagedata></v:shape><o:p></o:p></P></TD></TR>
<TR style="HEIGHT: 11pt; mso-yfti-irow: 4; mso-yfti-lastrow: yes">
<TD style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #d4d0c8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 1pt solid; WIDTH: 519.4pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 1pt solid; HEIGHT: 11pt; BACKGROUND-COLOR: transparent; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" width=693 colSpan=2>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; mso-layout-grid-align: none">注  1  垂直式为长度<st1:chmetcnv UnitName="m" SourceValue="3" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">3m</st1:chmetcnv>左右的接地极；<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; mso-layout-grid-align: none">    2  单根水平式为长度<st1:chmetcnv UnitName="m" SourceValue="60" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">60m</st1:chmetcnv>左右的接地极；<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; mso-layout-grid-align: none">    3  复合式中，<I style="mso-bidi-font-style: normal">S</I>为大于<st1:chmetcnv UnitName="m2" SourceValue="100" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">100m<SUP>2</SUP></st1:chmetcnv>的闭合接地网的面积；<I style="mso-bidi-font-style: normal">r</I>为与接地网面积<I style="mso-bidi-font-style: normal">S</I>等值的圆的半径，即等效半径，m。<o:p></o:p></P></TD></TR></TABLE></DIV>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; mso-layout-grid-align: none"><B style="mso-bidi-font-weight: normal"><o:p> </o:p></B></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><v:shape id=_x0000_i1028 style="WIDTH: 221.25pt; HEIGHT: 33pt" type="#_x0000_t75" o:ole=""><v:imagedata src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image007.wmz" o:title=""></v:imagedata></v:shape>Ω<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>参考答案：B<o:p></o:p></P>

keast

<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>9. 变电所低压配电系统TN-S接地系统形式，一电动机额定电压为380V，用3*50+1*25 <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>mm<SUP>2</SUP>电缆供电。已知该电缆单位长度的相保电阻RL＝1.59Ω/km。当发生A相碰壳短路时，计算电机外壳上的对地电位（忽略系统及变压器电阻抗忽，略电缆感抗），最接近下列哪值 <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>A. U<SUB>C</SUB>＝110V   B. U<SUB>C</SUB>＝147V  C. U<SUB>C</SUB>＝253V  D. U<SUB>C</SUB>＝220V <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><o:p> </o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>相线导体截面为保护导体截面的2倍，相线导体电阻为保护导体电阻的一半，<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"> <v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect"></v:path><o:lock v:ext="edit" aspectratio="t"></o:lock></v:shapetype><v:shape id=_x0000_i1025 style="WIDTH: 68.25pt; HEIGHT: 18pt" type="#_x0000_t75" o:ole=""><v:imagedata src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image001.wmz" o:title=""></v:imagedata></v:shape><o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>∴ 接地故障电流<v:shape id=_x0000_i1026 style="WIDTH: 3in; HEIGHT: 35.25pt" type="#_x0000_t75" o:ole=""> <v:imagedata src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image003.wmz" o:title=""></v:imagedata></v:shape><o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>接触电压<v:shape id=_x0000_i1027 style="WIDTH: 212.25pt; HEIGHT: 35.25pt" type="#_x0000_t75" o:ole=""> <v:imagedata src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image005.wmz" o:title=""></v:imagedata></v:shape>V<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>参考答案：B <o:p></o:p></P>

keast

<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>10某企业有一2MW的异步电动机，接于车间内配电屏的3kV出线上,若3kV电网的总单相接地电容电流为<st1:chmetcnv UnitName="a" SourceValue="10.5" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">10.5A</st1:chmetcnv>,试解答如下问题: <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>(1)为保护该电动机绕组的相间短路应装设下列哪种保护?并说明原因. <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>A 电流速断保护                                         B 纵联差动保护 <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>C 首先考虑电流速断保护,灵敏度不满足要求时装设差动保护  D 失步保护 <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><o:p> </o:p></P>
<P style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 17.95pt; mso-pagination: none; mso-layout-grid-align: none; mso-char-indent-count: 1.71">根据&lt;&lt;电力装置的继电保护和自动装置设计规范(GB 50062-92)&gt;&gt; 第<st1:chsdate w:st="on" IsROCDate="False" IsLunarDate="False" Day="30" Month="12" Year="1899">9.0.2</st1:chsdate>条 “┅ ┅二、2MW及以上的电动机，或电流速断保护灵敏系数不符合要求的2MW以下电动机，应装设纵联差动保护。┅ ┅”的规定<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>参考答案：B <o:p></o:p></P>

keast

<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>(2)电动机回路单相接地电流<st1:chmetcnv UnitName="a" SourceValue="6" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">6A</st1:chmetcnv>,对电动机接地保护的配置下列哪种方式是正确的?并说明原因. <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>A 不需装接地保护                          B 可装设接地检测装置 <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>C 需装设接地保护,保护装置动作于跳闸或信号 D 需装设接地保护,保护装置只能动作于信号 <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><o:p> </o:p></P>
<P style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 17.95pt; mso-pagination: none; mso-layout-grid-align: none; mso-char-indent-count: 1.71">根据&lt;&lt;电力装置的继电保护和自动装置设计规范(GB 50062-92)&gt;&gt; 第<st1:chsdate w:st="on" IsROCDate="False" IsLunarDate="False" Day="30" Month="12" Year="1899">9.0.3</st1:chsdate>条 “对单相接地故障，当接地电流大于<st1:chmetcnv UnitName="a" SourceValue="5" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">5A</st1:chmetcnv>时，应装设有选择性的单相接地保护；当接地电流小于<st1:chmetcnv UnitName="a" SourceValue="5" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">5A</st1:chmetcnv>时，可装设接地检测装置。<o:p></o:p></P>
<P style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 17.95pt; mso-pagination: none; mso-layout-grid-align: none; mso-char-indent-count: 1.71">单相接地电流为<st1:chmetcnv UnitName="a" SourceValue="10" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">10A</st1:chmetcnv>及以上时，保护装置动作于跳闸；单相接地电流为<st1:chmetcnv UnitName="a" SourceValue="10" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">10A</st1:chmetcnv>以下时，保护装置可动作于跳闸或信号。” 的规定<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left>参考答案：C <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-pagination: widow-orphan; tab-stops: 45.8pt 91.6pt 137.4pt 183.2pt 229.0pt 274.8pt 320.6pt 366.4pt 412.2pt 458.0pt 503.8pt 549.6pt 595.4pt 641.2pt 687.0pt 732.8pt; mso-layout-grid-align: none" align=left><o:p> </o:p></P>

keast

<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; mso-layout-grid-align: none">11某用户在某公共连接点输入的5次谐波电流<st1:chmetcnv UnitName="a" SourceValue="17" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">17A</st1:chmetcnv>，另一用户的5次谐波电流<st1:chmetcnv UnitName="a" SourceValue="11" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">11A</st1:chmetcnv>，二者之间的相位角150度，问叠加后的5次谐波电流是多少？ <o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-layout-grid-align: none" align=left><o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 17.95pt; TEXT-ALIGN: left; mso-layout-grid-align: none; mso-char-indent-count: 1.71" align=left>根据《电能质量 公用电网谐波GB/T 14549—93）》附录C中的C2 两个谐波源的同次谐波电流在一条线路的同一相上叠加，当相位角已知时按式(C4)式计算<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-layout-grid-align: none" align=left><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"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect"></v:path><o:lock v:ext="edit" aspectratio="t"></o:lock></v:shapetype><v:shape id=_x0000_i1025 style="WIDTH: 171pt; HEIGHT: 23.25pt" type="#_x0000_t75" o:ole=""><v:imagedata src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image001.wmz" o:title=""></v:imagedata></v:shape>(C4)<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-layout-grid-align: none" align=left>式中<I>I</I><SUB>h1</SUB>——谐波源1的第<I>h </I>次谐波电流，A；<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 21pt; TEXT-ALIGN: left; mso-layout-grid-align: none; mso-char-indent-count: 2.0" align=left><I>I</I><SUB>h2</SUB>——谐波源2的第<I>h </I>次谐波电流，A；<o:p></o:p></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-INDENT: 21pt; TEXT-ALIGN: left; mso-layout-grid-align: none; mso-char-indent-count: 2.0" align=left>θ<SUB>h</SUB>——谐波源1和谐波源2的第<I>h </I>次谐波电流之间的相位角。<B><o:p></o:p></B></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LAYOUT-GRID-MODE: char; TEXT-ALIGN: left; mso-layout-grid-align: none" align=left>代入数据I5=（17*17+11*11+2*17*11*COS150）1/2次方=9.3A<o:p></o:p></P>

<div style="color:#A48E7B;text-align:right">「该帖子被 keast 在 2008-2-27 13:45:56 编辑过」</div>

keast

明天接着贴，今天先休息了，呵呵！希望对大家的考试有点作用。

zyf6737

你做了一件大好事。我们不胜感激！对我们今年考试的人很有帮助！！谢谢！！！