From 7f60ea012dd2524dae921a2a35adbf7ef21f2bb6 Mon Sep 17 00:00:00 2001
From: prashantsinalkar
Date: Tue, 10 Oct 2017 12:27:19 +0530
Subject: initial commit / add all books

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+//Book name: Fundamentals of electrical drives by Mohamad A. El- Sharkawi
+//chapter 6
+//example 6.1
+//edition 1
+//publisher and place:Nelson Engineering
+clc;
+clear;
+Vs=150;//source voltage of DC shunt motor in volt
+n1=1200;//synchronous speed in rpm
+Ra=1;//armature resistance in ohm
+Rf=150;//field resistance in ohm
+I=10;//line current in ampere
+If=(Vs/Rf);//Field current before adding the resistance in ampere
+disp('a)Calculate the resistance that should be added to the armature circuit to reduce the speed by 50%')
+//consider that the motoring point 1 represents without adding resistance & point 2 for the operating point at 50% load reduction
+Ia1=I-If;//armature current without adding resistance
+n2=0.5*n1;//50% speed is reduced
+Ea1=Vs-(Ia1*Ra);//speed equation at operating point 1
+Radd=Ea1/(2*Ia1);//Obtained from the equation of Ea1/Ea2=n1/n2
+disp(Radd,'The resistance which should be added to reduce the speed by 50% in ohm is:')
+disp('b)To calculate the motor efficiency')
+Prloss=100;//rotational loss in watt
+Pfloss=If^(2)*Rf;//field loss in watt
+Paloss=Ia1^(2)*Ra//armature losses in watt
+Pin=Vs*I;//Input power in watt
+Ploss=Prloss+Pfloss+Paloss;//Total losses before adding armature resistance in watt
+Ploss1=Prloss+Pfloss+Paloss*(Ra+Radd);//Total losses after adding armature resistance in watt
+eff=((Pin-Ploss)/Pin)*100;//efficiency of the motor without adding resistance in % 
+eff1=((Pin-Ploss1)/Pin)*100;//efficiency of the motor with adding resistance in %
+disp(eff,'The efficiency of the motor without adding resistance in % is:')
+disp(eff1,'The efficiency of the motor with adding resistance in % is:')
+disp('c)To calculate the resistance to be added to the armature for the holding operation')
+//set motor speed equal to zero
+Radd=(Vs/Ia1)-Ra;
+disp(Radd,'The resistance to be added to the armature for the holding operation in ohm is:')
-- 
cgit