From b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b Mon Sep 17 00:00:00 2001
From: priyanka
Date: Wed, 24 Jun 2015 15:03:17 +0530
Subject: initial commit / add all books

---
 1938/CH2/EX2.15/2_15.jpg | Bin 0 -> 46291 bytes
 1938/CH2/EX2.15/2_15.sce |  30 ++++++++++++++++++++++++++++++
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 create mode 100755 1938/CH2/EX2.15/2_15.sce

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diff --git a/1938/CH2/EX2.15/2_15.sce b/1938/CH2/EX2.15/2_15.sce
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+clc,clear
+printf('Example 2.15\n\n')
+
+shaft_output = 80*746 //coverted to watts
+eta= 80/100 //efficiency
+V=250
+N_1=1200
+R_a=0.04,R_sh = 250 //armature and shunt field resistance
+power_input = shaft_output/eta
+I_L= power_input /V
+I_sh= V / R_sh
+I_a = I_L - I_sh
+E_b1 = V - I_a*R_a
+
+gross_mechanical_power= E_b1*I_a //electrical equivalent of mechanical power developed
+stray_losses =  gross_mechanical_power - shaft_output
+printf('Mechanical power developed on full load = %.3f kW\n',gross_mechanical_power/1000)
+
+//on no load shaft_output=0 and entire gross power is used to overcome stray losses
+Eb0_Ia0= stray_losses
+//E_b0 = V - I_a0*R_a  ... solving for I_0
+p=[R_a -V Eb0_Ia0]
+roots(p)
+I_a0=ans(2) //first root is ignored since its too large
+I_L0 =I_sh+I_a0 //current drawn from supply
+E_b0 = V - I_a0*R_a 
+
+//From speed equation N (prop.) E_b
+N_0 = N_1*(E_b0/E_b1)
+printf('No load speed and current are %.4f rpm and %.2f A respectively',N_0,I_L0)
-- 
cgit