<p style="text-align:justify"><img alt="" src="https://edupmquestionhelp.s3.ap-south-1.amazonaws.com/hint/uploads/images/16257253711625725371.jpg" style="height:505px; width:800px" /></p>

<p style="text-align:justify">&nbsp;</p>

<p style="text-align:justify">&nbsp;</p>

<p style="text-align:justify"><span style="font-size:14px">Figure 7.43 shows a single line diagram of a portion of a power system network. Bracketed figures show the fault levels for triple line fault on respective buses. The fault currents for L-g fault are tabulated below:</span></p>

<p style="margin-left:48px; text-align:center">&nbsp;</p>

<p style="margin-left:48px; text-align:center">&nbsp;</p>

<table cellspacing="0" class="MsoTableGrid" style="border-collapse:collapse; border:none; margin-left:160px; width:900px">
	<caption>
	<p><strong><span style="font-size:18px">Table 7.19: Fault Currents for L-g Fault at Buses</span></strong></p>
	</caption>
	<tbody>
		<tr>
			<td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:1px solid black; vertical-align:top; width:164px">
			<div style="text-align:center"><span style="font-size:28px">Bus</span></div>
			</td>
			<td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:1px solid black; vertical-align:top; width:157px">
			<div style="text-align:center"><span style="font-size:28px">Fault Current for L-g Fault in Amp</span></div>
			</td>
		</tr>
		<tr>
			<td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:164px">
			<div style="text-align:center"><span style="font-size:28px">A</span></div>
			</td>
			<td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:157px">
			<div style="text-align:center"><span style="font-size:28px">6680</span></div>
			</td>
		</tr>
		<tr>
			<td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:164px">
			<div style="text-align:center"><span style="font-size:28px">B</span></div>
			</td>
			<td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:157px">
			<div style="text-align:center"><span style="font-size:28px">3564</span></div>
			</td>
		</tr>
		<tr>
			<td style="border-bottom:1px solid black; border-left:1px solid black; border-right:1px solid black; border-top:none; vertical-align:top; width:164px">
			<div style="text-align:center"><span style="font-size:28px">C</span></div>
			</td>
			<td style="border-bottom:1px solid black; border-left:none; border-right:1px solid black; border-top:none; vertical-align:top; width:157px">
			<div style="text-align:center"><span style="font-size:28px">7400</span></div>
			</td>
		</tr>
	</tbody>
</table>

<p style="margin-left:48px; text-align:justify">&nbsp;</p>

<p style="margin-left:48px; text-align:justify">&nbsp;</p>

<p style="margin-left:48px; text-align:justify"><span style="font-size:14px">The other data required is as follows:</span></p>

<p style="margin-left:48px; text-align:justify">&nbsp;</p>

<ul>
	<li style="text-align:justify">
	<p><span style="font-size:14px">Each relay group at all relaying points is wired for three overcurrent and one earth-fault protection scheme.</span></p>
	</li>
	<li style="text-align:justify">
	<p><span style="font-size:14px">Relays R<sub>1</sub> to R<sub>11</sub> are directional or non-directional (as per requirement) normal inverse IDMT overcurrent and earth-fault relays. The setting ranges are</span></p>
	</li>
</ul>

<p style="margin-left:96px; text-align:justify"><span style="font-size:14px">Overcurrent Units: 50-200 % of 1 amp in seven equal steps.</span></p>

<p style="margin-left:96px; text-align:justify"><span style="font-size:14px">Earth-fault Units: 10-40 % of 1 amp in seven equal steps.</span></p>

<ul>
	<li style="text-align:justify">
	<p><span style="font-size:14px">Maximum Power flowing (under normal load condition) through 220 kV lines is 150 MW at 0.85 pf lag. This includes 10 % overload.</span></p>
	</li>
	<li style="text-align:justify">
	<p><span style="font-size:14px">Relaying points R<sub>10</sub> and R<sub>11</sub> feed 66/11 kV substations located at different places. (They are not parallel feeders).</span></p>
	</li>
	<li style="text-align:justify">
	<p><span style="font-size:14px">Time of operation of relays is definite and constant beyond PSM equal to 20 as 2.3 seconds at TMS equal to 1.0.</span></p>
	</li>
	<li style="text-align:justify">
	<p><span style="font-size:14px">TMS of phase and ground relays R<sub>10</sub>/R<sub>11</sub> = 0.1.</span></p>
	</li>
	<li style="text-align:justify">
	<p><span style="font-size:14px">The excitation current of all the CTs is 0.03 amp.</span></p>
	</li>
</ul>

<p>&nbsp;</p>

<p><span style="font-size:14px"><strong>&nbsp;P. S. phase of relays R<sub>4</sub>/R<sub>5</sub> shall be set at</strong></span></p>

<p style="margin-left:48px; text-align:justify">&nbsp;</p>