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+// Electric Machinery and Transformers
+// Irving L kosow 
+// Prentice Hall of India
+// 2nd editiom
+
+// Chapter 12: POWER,ENERGY,AND EFFICIENCY RELATIONS OF DC AND AC DYNAMOS
+// Example 12-5
+
+clear; clc; close; // Clear the work space and console.
+
+// Given data
+P = 10000 ; // Power rating of the shunt generator in W
+V = 230 ;// Voltage rating of the shunt generator in volt
+S = 1750 ; // Speed in rpm of the shunt generator
+R_a = 0.2 ; // Armature resistance
+// Calculated values from Ex.12-1
+P_r = 489.2 ; // Shunt generator rotational losses in W
+Vf_If = 230 ; // Shunt field circuit loss in W
+I_a_rated = 44.5 ; // Rated armature current in A
+
+// Calculations
+// case a
+I_a = sqrt( (Vf_If + P_r) / R_a ); // Armature current in A for max.efficiency
+
+// case b
+LF = I_a / I_a_rated ; // Load fraction
+LF_percent = LF*100 ; // Load fraction in percent 
+
+// case c
+P_k = Vf_If + P_r ;
+eta_max = (P*LF)/( (P*LF) + (Vf_If + P_r) + P_k ) * 100; // Maximum efficiency
+
+// case d
+// subscript d for LF indicates case d
+LF_d = sqrt(P_k/(I_a_rated^2*R_a)) ; // Load fraction from fixed losses and rated variable losses
+
+// Display the results
+disp("Example 12-5 Solution : ");
+
+printf(" \n a: Armature current for max.efficiency :\n    I_a = %.f A \n",I_a);
+
+printf(" \n b: Load fraction :\n    L.F. = %.1f percent = %.3f*rated \n",LF_percent,LF);
+
+printf(" \n c: Maximum efiiciency :\n    η = %.2f percent \n",eta_max);
+
+printf(" \n d: Load fraction from fixed losses and rated variable losses :");
+printf(" \n    L.F. = %.3f*rated",LF_d);