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+// Example 12.1
+// Determine (a) Field circuit resistance (b) Field rheostat setting that will
+// provide no load voltage of 140V (c) Armature voltage if the rheostat is set
+// to 14.23 ohm (d) Field rheostat setting that will cause critical resistance
+// (e) Armature voltage at 80 percent rated speed (f) Rheostat setting required
+// to obtain no load armature voltage of 140V if shunt field is separately
+// excited from a 120V DC source
+// Page No. 479
+
+clc;
+clear;
+close;
+
+// Given data
+Ea=156; // No load voltage
+If=4.7; // Shunt field current
+If140=2.35; // New field current at Ea=140V
+Eanew=140; // No load voltage
+Ifnew=3.2; // Field current corresponding to no load voltage
+Ea1=0; // First arbitrary voltage
+Ea2=100; // Second arbitrary voltage
+Vf=120;
+V=130; // Intersection of I1 and I2
+Rrheonew=14.42; // Rheostat set to new settings
+Va=116; // Intersection of field resistance line with the low
+ // speed magnetization curve
+
+
+
+//(a) Field circuit resistance
+Rf=Ea/If; // Field circuit resistance
+
+// (b) Field rheostat setting that will provide no load voltage of 140V
+Rrheo=(Eanew/Ifnew)-Rf;
+
+//(c) Armature voltage if the rheostat is set to 14.23 ohm
+Rnew=Rf+Rrheonew; // New field resistance
+If1=Ea1/(Rf+Rrheo); // Field current corresponding to first arbitrary voltage
+If2=Ea2/(Rf+Rrheo); // Field current corresponding to second arbitrary voltage
+
+// (d) Field rheostat setting that will cause critical resistance
+Rcr=Eanew/If140; // Critical resistance
+
+// (e) Armature voltage at 80 percent rated speed
+// Ea80=0.80*Ea;
+Ea80=116;
+
+//(f) Rheostat setting required to obtain no load armature voltage of 140V if
+// shunt field is separately excited from a 120V DC source
+Rrheo1=(Vf/Ifnew)-Rf;
+
+// Display result on command window
+printf("\n Field circuit resistance = %0.2f Ohm",Rf);
+printf("\n Field rheostat setting that will provide no load voltage of 140V = %0.2f Ohm ",Rrheo);
+printf("\n Armature voltage if the rheostat is set to 14.23 ohm = %0.0f V ",V);
+printf("\n Field rheostat setting that will cause critical resistance = %0.1f Ohm ",Rcr);
+printf("\n Armature voltage at 80 percent rated speed (V)= %0.0f ",Ea80);
+printf("\n Rheostat setting required = %0.2f Ohm ",Rrheo1);
+