initial commit / add all books

1 files changed, 45 insertions, 0 deletions

diff --git a/3760/CH4/EX4.19/Ex4_19.sce b/3760/CH4/EX4.19/Ex4_19.sce
new file mode 100644
index 000000000..e5e438788
--- /dev/null
+++ b/3760/CH4/EX4.19/Ex4_19.sce
@@ -0,0 +1,45 @@
+clc;

+n=1500; // speed of generator

+// data is given in question for magnetising curve at n=1500 rpm

+If=[ 0 0.4 0.8 1.2 1.6 2 2.4 2.8 3];

+Ea=[6 60 120 172.5 202.5 221 231 237 240];

+subplot(221);

+plot(If,Ea);

+xlabel('field current');

+ylabel('generated EMF');

+title('Magnetising curve for n=1500');

+disp('case a')

+rf=100; // field resistance

+// rf=100 lets say voltage=240 and field current=2.4 which is shown by point A, straight line passing through A and origin meets magnetising current at B which is no load voltage

+Eo=230; 

+printf('No load voltage is %f V\n',Eo);

+disp('case b');

+// a line OF is drawn passing through origin slope of this line gives critical resistance

+vt=180; // terminal voltage 

+ifl=1.2; // field current corresponding to terminal voltage

+rfl=vt/ifl;

+printf('Critical value of shunt field resistance is %f ohms\n',rfl);

+disp('case c');

+// Choose S (any point) on linear part of magnetising curve.A vertical line from S meets field resistance line at t and horizontal line at y. Now

+e1=90; // terminal voltage corresponding to point s

+e2=60; // terminal voltage corresponding to point t

+n2=(e2/e1)*n; 

+printf('Critical speed for given shunt field resistance is %f rpm\n',n2);

+disp('case d');

+n3=1200; // speed at which magnetising curve is drawn

+// data for magnetising curve at n=1200 can be obtained by multiplying voltage of magnetising curve at n=1500 by factor 1200/1500 and at point C field resistance line for 100 ohms meet at magnetising curve .This point gives no load EMF

+EAn=Ea*(n3/n);

+subplot(222);

+plot(If,EAn);

+xlabel('field current');

+ylabel('generated EMF');

+title('Magnetising curve for n=1200');

+Eo=165; 

+printf('No load EMF is %f V\n',Eo);

+disp('case e');

+ia=50; // armature current

+ra=0.3; // armature resistance

+vd=ia*ra; // armature resistance drop

+// To obtain terminal voltage cut OD equal to vd and draw DG parallel to field resistance line. From G draw vertical line  meeting field resistance line at H. Point corresponding to H gives terminal voltage which is 

+vt=207; 

+printf('Terminal voltage is %f V\n',vt);