1 files changed, 19 insertions, 0 deletions
diff --git a/1938/CH3/EX3.21/3_21.sce b/1938/CH3/EX3.21/3_21.sce
new file mode 100755
index 000000000..22dfd6934
--- /dev/null
+++ b/1938/CH3/EX3.21/3_21.sce
@@ -0,0 +1,19 @@
+clc,clear
+printf('Example 3.21\n\n')
+
+V_avg = (220+190)/2  //average voltage across load
+I_avg=12,R_a=0.5,R_sh=250
+W_dash=V_avg*I_avg  //power absorbed 
+t_1=30,t_2=5
+W=W_dash*(t_2/(t_1-t_2))
+V=250,I=22  //input current
+I_sh = V/R_sh
+I_a= I - I_sh
+arm_cu_loss = R_a*I_a^2 //armature copper loss
+shunt_field_cu_loss =  V*I_sh  //shunt field copper loss
+total_losses= shunt_field_cu_loss + arm_cu_loss + W
+
+machine_input = V*I
+machine_output = machine_input - total_losses 
+eta_m=100*(machine_output /machine_input )  //efficiency when running as motor
+printf('Efficiency of machine when opeating as motor taking current of 22A on 250V supply is \n%.1f percent',eta_m)