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 --- 3811/CH6/EX6.1/Ex6_1.jpg | Bin 0 -> 65909 bytes 3811/CH6/EX6.1/Ex6_1.sce | 35 +++++++++++++++++++++++++++++++++++ 2 files changed, 35 insertions(+) create mode 100644 3811/CH6/EX6.1/Ex6_1.jpg create mode 100644 3811/CH6/EX6.1/Ex6_1.sce (limited to '3811/CH6/EX6.1') diff --git a/3811/CH6/EX6.1/Ex6_1.jpg b/3811/CH6/EX6.1/Ex6_1.jpg new file mode 100644 index 000000000..f28820754 Binary files /dev/null and b/3811/CH6/EX6.1/Ex6_1.jpg differ diff --git a/3811/CH6/EX6.1/Ex6_1.sce b/3811/CH6/EX6.1/Ex6_1.sce new file mode 100644 index 000000000..65c68b55a --- /dev/null +++ b/3811/CH6/EX6.1/Ex6_1.sce @@ -0,0 +1,35 @@ +//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