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diff --git a/Working_Examples/2777/CH6/EX6.11/Ex6_11.sce b/Working_Examples/2777/CH6/EX6.11/Ex6_11.sce new file mode 100755 index 0000000..442c25c --- /dev/null +++ b/Working_Examples/2777/CH6/EX6.11/Ex6_11.sce @@ -0,0 +1,81 @@ +
+// ELECTRICAL MACHINES
+// R.K.Srivastava
+// First Impression 2011
+// CENGAGE LEARNING INDIA PVT. LTD
+
+// CHAPTER : 6 : SYNCHRONOUS MACHINES
+
+// EXAMPLE : 6.11
+
+clear ; clc ; close ; // Clear the work space and console
+
+
+// GIVEN DATA
+
+printf("\n EXAMPLE : 6.11 : \n\n Given Data \n");
+printf("\n Voc( V) 12 13 13.8 14.5 15.1 \n");
+printf("\n If(A) 175 200 225 250 275 \n\n");
+V = 11*10^3; // Operating voltage of the Synchronous generator in Volts
+VA = 50*10^6; // VA rating of the Synchronous generator in Volts-Amphere
+f = 50; // Operating Frequency of the Synchronous generator in Hertz
+N = 1500; // Speed of the Synchronous generator in RPM
+If_scc = 200; // SCC test field Rated current in Amphere at rated Short circuit current
+If_zpf = 400; // ZPF test field Rated current in Amphere at rated voltage and rated current
+pf = 0.8; // Power factor (lagging)
+
+
+// CALCULATIONS
+// Some of the data obtained from OCC and SCC test Graph or Pottier triangle in Figure6.30 & Page no:-413
+
+Vt = V/sqrt(3); // Rated per phase Voltage in Volts
+Ia = VA/(sqrt(3)*V); // Rated Armature Current in Amphere
+pfa = acosd(pf); // Power factor angle in degree
+O = 13000; // Open circuit Voltage in Volts obtained from OCC and SCC test Graph or Pottier triangle Figure6.30 & Page no:-413
+Xs = O/(sqrt(3)*Ia); // Synchronous reactance per phase in Ohms
+BC = 4000; // Open circuit Voltage in Volts obtained from OCC and SCC test Graph or Pottier triangle Figure6.30 & Page no:-413
+Xl = BC/(sqrt(3)*Ia ); // Per phase leakage reactance in Ohms
+
+// For Case (a) General (ZPF) Method
+
+Er_a = Vt+Ia*(cosd(pfa)-%i*sind(pfa))*(%i*Xl); // Induced EMF in Volts
+R_a = 220; A_a = 200; //From OCC the field current required for Er_a (Should be in Line-line Voltage) Er_a = 13776V will get R_a & A_a value Respectively from SCC (Figure6.30 & Page no:-403)
+angle_a = 140.3; // Angle between R_a & A_a = 90'+13.43'+36.87' = 140.3'
+F_a = sqrt((R_a^2)+(A_a^2)-(2*R_a*A_a*cosd(angle_a))); // From phasor diagram in figure 6.16(a) & Page no:-388 the neccessary field excitation in Amphere
+Eo_a = 20000; // Corresponding to field current F_a = 470.90 A the open circuit EMF from OCC is 20000 V (Figure6.30 & Page no:-413)
+r_a = 100*((Eo_a-V)/V); // Percentage regulation
+
+
+// For Case(b) EMF Method
+
+Er_b = Vt+Ia*(cosd(pfa)-%i*sind(pfa))*(%i*Xs); // Induced Voltage in Volts
+F_b = 500; //From OCC the field current required for Er_b (Should be in Line-line Voltage) Er_b = 21404 V will get 500A from SCC (Figure6.15 & Page no:-386)
+
+// For Case (c) MMF Method
+
+Er_c = Vt+Ia*(cosd(pfa)-%i*sind(pfa))*0; // Induced Voltage in Volts ( Zero is multipied because Armature reistance is zero (not mentioned))
+R_c = 160; A_c = 200; //From OCC the field current required for Er_c (Should be in Line-line Voltage) Er_c = 11000 V will get R_c & A_c value Respectively from SCC (Figure6.30 & Page no:-413)
+angle_c = 126.27; // Angle between R_c & A_c = 90'-0'+36.87' = 126.27' {can refer figure 6.21a at page no:-400}
+F_c = sqrt((R_c^2)+(A_c^2)-(2*R_c*A_c*cosd(angle_c))); // From phasor diagram {can refer figure 6.21a at page no:-400} the neccessary field excitation in Amphere
+
+
+// For Case (d) ASA Method
+
+Er_d = Vt+Ia*(cosd(pfa)-%i*sind(pfa))*(%i*Xl); // Induced Voltage in Volts
+R_d = 220; A_d = 200; //From OCC the field current required for Er_d (Should be in Line-line Voltage) Er_d = 13800 V will get R_d & A_d value Respectively from SCC (Figure6.30 & Page no:-413)
+angle_d = 126.87; // Angle between R_d & A_d = 90'+36.87' = 126.87'{can refer figure 6.22a at page no:-40}
+F_d1 = sqrt((R_d^2)+(A_d^2)-(2*R_d*A_d*cosd(angle_d))); // from Phasor diagram {can refer figure 6.2a at page no:-400 The neccessary field excitation in Amphere
+F_d = F_d1 + 30; // from Phasor diagram {can refer figure 6.2a at page no:-400 The Total neccessary field excitation in Amphere
+
+
+// DISPLAY RESULTS
+
+disp(" SOLUTION :-");
+printf("\n (a) Leakage Reactance, Xl = %.2f Ohms \n",Xl)
+printf("\n (b) Synchronous Reactance, Xs = %.2f Ohms \n",Xs)
+printf("\n For Case (a) General (ZPF) Method \n Field Current required for maintaing the rated terminal voltage for rated kVA rating at %.2f Lagging Power factor , F = %.2f A \n",pf,F_a)
+printf("\n For Case (a) EMF Method \n Field Current required for maintaing the rated terminal voltage for rated kVA rating at %.2f Lagging Power factor , F = %.f A \n",pf,F_b)
+printf("\n For Case (a) MMF Method \n Field Current required for maintaing the rated terminal voltage for rated kVA rating at %.2f Lagging Power factor , F = %.2f A \n",pf,F_c)
+printf("\n For Case (a) ASA Method \n Field Current required for maintaing the rated terminal voltage for rated kVA rating at %.2f Lagging Power factor , F = %.f A \n",pf,F_d)
+printf("\n\n [ TEXT BOOK SOLUTION IS PRINTED WRONGLY ( I verified by manual calculation )]\n" );
+printf("\n WRONGLY PRINTED ANSWERS ARE :- For Case (a) General (ZPF) Method \n (a) Field Current required for maintaining the rated terminal voltage for rated kVA rating at %.2f Lagging Power factor , F = 470.90 A instead of %.2f A \n",pf,F_a);
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