<ol>
	<li>
	<p style="text-align:justify"><span style="font-size:14px"><u>Symmetrical (Balanced) Faults:</u></span></p>
	</li>
</ol>

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

<p style="text-align:justify"><span style="font-size:14px">Symmetrical faults are faults involving all the three phases. Triple line or L-L-L (R-Y-B) and triple line to ground or L-L-L-g (R-Y-B-g) faults are symmetrical faults.</span></p>

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

<ol start="2">
	<li>
	<p style="text-align:justify"><span style="font-size:14px"><u>Asymmetrical Unbalanced) Faults:</u></span></p>
	</li>
</ol>

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

<p style="text-align:justify"><span style="font-size:14px">The faults involving only one or two phases are categorized as asymmetrical faults. Single line to ground (L-g), double line to ground (L-L-g) and double line (L-L) faults are asymmetrical faults. For a three-phase power system, there can be 10 different faults. These are R-g, Y-g,</span></p>

<p style="text-align:justify"><span style="font-size:14px">&nbsp;B-g, R-Y, Y-B, B-R, R-Y-g, Y-B-g, B-R-g and R-Y-B. R-Y-B and R-Y-B-g are the same faults as far as magnitude of fault currents is concerned. When an R-Y-B-g fault occurs, the three phase currents (I<sub>Rf</sub>, I<sub>Yf</sub> and I<sub>Bf</sub>) may be ten times (or even more) the rated full load current (referred to as CMR or Continuous Maximum Rating) for which the electrical equipment is designed. However, the vector sum of these three currents is zero,</span></p>

<p style="text-align:justify"><span style="font-size:14px">i.e., I<sub>Rf</sub> + I<sub>Yf</sub> + I<sub>Bf</sub>= 0.</span></p>

<p style="text-align:justify"><span style="font-size:14px">Hence no current passes through the ground (Figure 4.1).</span></p>

<p><img alt="" src="https://edupmquestionhelp.s3.ap-south-1.amazonaws.com/hint/uploads/images/16159626641615962664.jpg" style="height:551px; width:800px" /></p>

<p style="text-align:justify"><span style="font-size:14px">Therefore, with reference to fault current values, R-Y-B and R-Y-B-g faults are same. Hence their fault current analysis is identical. These faults, however, differ in case of problem of overvoltage as will be discussed later.</span></p>

<p style="text-align:justify"><span style="font-size:14px">If one conductor of transmission line gets broken, it is a kind of abnormality which is known as single phasing. This abnormality is also called &ldquo;open conductor&rdquo; or &ldquo;broken conductor&rdquo;.</span></p>