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+// Electric Machinery and Transformers
+// Irving L kosow 
+// Prentice Hall of India
+// 2nd editiom
+
+// Chapter 9: POLYPHASE INDUCTION (ASYNCHRONOUS) DYNAMOS
+// Example 9-12
+
+clear; clc; close; // Clear the work space and console.
+
+// Given data as per Ex.9-10
+P = 4 ; // Number of poles in WRIM
+f = 60 ; // Frequency in Hz
+V = 220 ; // Line voltage in volt
+V_p = 220 ; // Phase voltage in volt (delta connection)
+hp_WRIM = 1 ; // Power rating of WRIM in hp
+S_r = 1740 ; // Full-load rated speed in rpm 
+R_r = 0.3 ; // rotor resistance per phase in ohm/phase 
+R_x = 0.7 ; // Added resistance in ohm/phase 
+X_lr = 1 ; // Locked rotor reactance in ohm
+
+// Calculations from Ex.9-10
+E_lr = V_p / 4 ; // Locked-rotor voltage per phase
+S = (120*f)/P ; // Speed in rpm of the rotating magnetic field
+
+// Calculations (Ex.9-12)
+P_in = (E_lr)^2 / (2*X_lr); // rotor power input(RPI) in W/phase
+P_in_total = P_in * 3 ; // Total 3-phase rotor power input(RPI) in W
+
+T_max = 7.04*(P_in_total/S); // Maximum torque developed in lb-ft
+
+s_b = R_r / X_lr ; // Slip
+
+s = s_b;
+S_r = S*(1 - s); // Rotor speed in rpm for T_max
+
+// Display the results
+disp("Example 9-12 Solution : ");
+
+printf(" \n Rotor power input (RPI) per phase is : ");
+printf(" \n P_in = %.1f W/phase \n",P_in);
+
+printf(" \n The total 3-phase rotor power input (RPI) is : ");
+printf(" \n P_in = %.1f W\n",P_in_total);
+
+printf(" \n Substituting in Eq.(9-19),\n T_max = %.2f lb-ft\n",T_max);
+printf(" \n Then, s_b = %.1f \n and S_r = %d rpm",s_b,S_r);