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+// Electric Machinery and Transformers

+// Irving L kosow 

+// Prentice Hall of India

+// 2nd editiom

+

+// Chapter 8: AC DYNAMO TORQUE RELATIONS - SYNCHRONOUS MOTORS

+// Example 8-6

+

+clear; clc; close; // Clear the work space and console.

+

+// Given data as per Example 8-4

+// Y-connected synchronous dynamo

+P = 2 ; // No. of poles

+hp = 1000 ; // power rating of the synchronous motor in hp

+V_L = 6000 ; // Line voltage in volt

+f = 60 ; // Frequency in Hz

+R_a = 0.52 ; // Effective armature resistance in ohm

+X_s = 4.2 ; // Synchronous reactance in ohm

+P_t = 811 ; // Input power in kW

+PF = 0.8 ; // Power factor leading

+

+// Calculated values from Example 8-4

+E_gp = 3687 ; // Generated voltage/phase in volt 

+

+I_a = 97.55 ; // Phase armature current in A

+

+phi = (42.45 - 0); // Phase angle between E_gp and I_a in degrees 

+// where 42.45 and 0 are phase angles of E_gp and I_a in degrees respectively.

+

+// Calculations

+// case a 

+P_p = E_gp * I_a * cosd(phi) / 1000; // Mechanical power developed per phase in kW

+

+P_t_a = 3 * P_p ; // Total mechanical power developed in kW

+

+// case b

+P_t_b = P_t_a / 0.746 ; // Internal power developed in hp at rated load

+

+// case c

+S = 120 * f / P ; // Speed of the motor in rpm

+T_int = ( P_t_b * 5252 ) / S ; // Internal torque developed in lb-ft

+

+// case d

+T_ext = ( hp * 5252 ) / 3600 ; // External torque developed in lb-ft

+eta = (T_ext / T_int) * 100 ; // Motor efficiency in percent

+

+// Display the results

+disp("Example 8-6 Solution : ");

+printf(" \n a: Similar to a dc motor, the mechanical power developed in the armature");

+printf(" \n    is the product of the induced EMF per phase, the armature current");

+printf(" \n    per phase, and the cosine of the angle between them.\n");

+printf(" \n    P_p = %.3f kW \n    P_t = %.1f kW \n", P_p, P_t_a );

+

+printf(" \n b: P_t = %.1f hp \n ", P_t_b );

+

+printf(" \n c: T_int = %.f lb-ft \n ", T_int );

+

+printf(" \n d: T_ext = %d lb-ft  \n", T_ext );

+printf(" \n    Motor Efficiency,\n    eta = %.1f percent ", eta );