Added new codeHEADmaster

25 files changed, 668 insertions, 0 deletions

diff --git a/3871/CH7/EX7.1/Ex7_1.sce b/3871/CH7/EX7.1/Ex7_1.sce
new file mode 100644
index 000000000..e884ff9ca
--- /dev/null
+++ b/3871/CH7/EX7.1/Ex7_1.sce
@@ -0,0 +1,19 @@
+//===========================================================================

+//chapter 7 example 1

+

+clc;clear all;

+

+

+//variable declaration

+P	= 250;		//wattmeter reading in watts

+Rp	= 2000;		//pressure coil circuit resistance in Ω

+VL	= 200;		//load voltage in V

+

+//calculations

+p	= (VL^2)/Rp;	//power lost in pressure coil in watts

+P1	= P-p;		//power lost in the pressure coil circuit in watts

+

+

+//result

+mprintf("power lost in the pressure coil circuit  = %3.2f watts",P1);

+

diff --git a/3871/CH7/EX7.10/Ex7_10.sce b/3871/CH7/EX7.10/Ex7_10.sce
new file mode 100644
index 000000000..6cea02795
--- /dev/null
+++ b/3871/CH7/EX7.10/Ex7_10.sce
@@ -0,0 +1,16 @@
+//===========================================================================

+//chapter 7 example 10

+

+clc;clear all;

+

+//variable declaration

+V1	= 200;		//voltage across an inductive load in volts

+V2	= 180;		//voltage across an nono- inductive resistor in volts

+V3	= 300;		//voltage across the two in series in volts

+

+//calculations

+x	= ((V3^2)-(V1^2)-(V2^2))/(2*V1*V2);	//cos(phi) 

+

+//result

+mprintf("power factor cos (phi) = %3.3f lagging",x);

+

diff --git a/3871/CH7/EX7.11/Ex7_11.sce b/3871/CH7/EX7.11/Ex7_11.sce
new file mode 100644
index 000000000..c3339acdb
--- /dev/null
+++ b/3871/CH7/EX7.11/Ex7_11.sce
@@ -0,0 +1,22 @@
+//===========================================================================

+//chapter 7 example 11

+

+clc;clear all;

+

+//variable declaration

+I1	= 2.5;		//current across an inductive load in A

+I2	= 2.4;		//current across an non- inductive resistor in A

+I3	= 4.5;		//current across the two in series in A

+V	= 250;		//supply voltage in V

+

+

+//calculations

+R	= V/I2;	// non- inductive resistance in Ω

+P	= ((I3^2)-(I1^2)-(I2^2))*(R/2);	//power absorbed by the load in watts

+Z	= V/I1;			//load impedance in Ω

+x	= ((I3^2)-(I1^2)-(I2^2))/(2*I1*I2);	//cos(phi) 

+

+//result

+mprintf("power absorbed by the load = %3.2f watts",P);

+mprintf("\nload impedance = %3.2f Ω",Z);

+mprintf("\npower factor cos (phi) = %3.4f lagging",x);

diff --git a/3871/CH7/EX7.12/Ex7_12.sce b/3871/CH7/EX7.12/Ex7_12.sce
new file mode 100644
index 000000000..25780fcc6
--- /dev/null
+++ b/3871/CH7/EX7.12/Ex7_12.sce
@@ -0,0 +1,17 @@
+//===========================================================================

+//chapter 7 example 12

+clc;clear all;

+

+//variable declaration

+V1	= 6600;		//primary voltage in V

+V2	= 110;		//secondary voltage in V

+I1	= 50;		//primary current in A

+I2	= 5;		//secondary voltage in A

+

+//calculations

+r	= V1/V2;		//hence transformation ratio of PT 

+r1	= I1/I2;		//transformation ratio of CT

+

+//result

+mprintf("transformation ratio of CT = %3.2f ",r1);

+

diff --git a/3871/CH7/EX7.13/Ex7_13.sce b/3871/CH7/EX7.13/Ex7_13.sce
new file mode 100644
index 000000000..cfbb55f0c
--- /dev/null
+++ b/3871/CH7/EX7.13/Ex7_13.sce
@@ -0,0 +1,14 @@
+//===========================================================================

+//chapter 7 example 13

+clc;clear all;

+

+//variable declaration

+m	= 10;		//wattmeter multiplying factor 

+

+//calculations

+x	= 100/5;		//CT ratio 

+y 	= 1000/100;	//PT ratio

+W	= x*y*m;		//new multiplying factor of wattmeter

+

+//result

+mprintf("new multiplying factor of wattmeter = %3.2f",W);

diff --git a/3871/CH7/EX7.14/Ex7_14.sce b/3871/CH7/EX7.14/Ex7_14.sce
new file mode 100644
index 000000000..5c7e5b9d1
--- /dev/null
+++ b/3871/CH7/EX7.14/Ex7_14.sce
@@ -0,0 +1,35 @@
+//===========================================================================

+//chapter 7 example 14

+clc;

+clear all;

+

+//variable declaration

+

+V	= 6000;		//load voltage in V

+I	= 100;		//load current in A

+p	= 0.5;		//power factor cos(phi) lagging

+theta	= 0;		//since wattmeter reads correctly

+x1      = 20;           // current transformers nominal ratio

+x2      = 60;           // potenetial transformers nominal ratio 

+e1      =-0.005;          // ration error 

+e2      = 0.01;         // ratio error 

+

+//calculations

+P	= V*I*p;		//actual power consumed in W

+phi	=acos(p);

+phi1    = (phi*180)/%pi;

+d	= -1;		//phase angle in ° 

+b	= 2;		//phase angle in ° 

+g	= phi1+d-theta1-b;	//phase angle in ° 

+theta1      =theta*180/%pi

+g1      = g*180/%pi;

+A       =cos(phi1)

+K   = (cos(phi1*%pi/180))/((cos(theta1*%pi/180))*(cos(g*%pi/180)));

+CT      =  x1*(1+e1);            //actual transformation ratio of CT

+PT          = x2*(1+e2);        //actual transformation ratio of PT

+P1          = P/(K*CT*PT);      //power indicated by wattmeter in kW

+T           = P/(x1*x2);        //true reading of wattmeter in kW

+e           = ((P1-T)/T)*100;     //percentage errror in %  

+//result

+mprintf("phase angle between the currents in CC and PC of wattmeter %3.2f ° ",K);

+mprintf("\npercentage error = %3.0f percentage ",e);

diff --git a/3871/CH7/EX7.15/Ex7_15.sce b/3871/CH7/EX7.15/Ex7_15.sce
new file mode 100644
index 000000000..0686bcc01
--- /dev/null
+++ b/3871/CH7/EX7.15/Ex7_15.sce
@@ -0,0 +1,20 @@
+//===========================================================================

+//chapter 7 example 15

+clc;

+clear all;

+

+//variable declaration

+W1	= 300;		//wattmeter reading in kW

+W2	= 100;		//wattmeter reading in kW

+	

+//calculations

+P	= W1+W2;		//input power in kW

+phi	= atan(((W1-W2)/(W1+W2))*sqrt(3));		//phase angle in radians

+phi1    = (phi*180)/%pi; 

+pf	=cos((phi1*%pi)/180);		//power factor lagging

+

+

+//result

+mprintf("input power = %3.2f kW",P);

+mprintf("power factor  = %3.3f lagging",pf);

+

diff --git a/3871/CH7/EX7.16/Ex7_16.sce b/3871/CH7/EX7.16/Ex7_16.sce
new file mode 100644
index 000000000..750409d15
--- /dev/null
+++ b/3871/CH7/EX7.16/Ex7_16.sce
@@ -0,0 +1,18 @@
+//===========================================================================

+//chapter 7 example 16

+

+clc;clear all;

+

+//variable declaration

+W1	= 20;		//wattmeter reading in kW

+W2	= -5;		//wattmeter reading in kW

+	

+//calculations

+P	= W1+W2;		//input power in kW

+phi	= atan(((W1-W2)/(W1+W2))*sqrt(3));		//phase angle in ° 

+pf	=cos(phi);		//power factor lagging

+

+//result

+mprintf("input power = %3.2f kW",P);

+mprintf("\npower factor  = %3.4f lagging",pf);

+

diff --git a/3871/CH7/EX7.17/Ex7_17.sce b/3871/CH7/EX7.17/Ex7_17.sce
new file mode 100644
index 000000000..015e0dbea
--- /dev/null
+++ b/3871/CH7/EX7.17/Ex7_17.sce
@@ -0,0 +1,26 @@
+//===========================================================================

+//chapter 7 example 17

+

+clc;clear all;

+

+//variable declaration

+P	= 30000;	//total power in kW

+pf	= 0.4;	//power factor assuming lagging

+

+//calculations

+phi	= acos(pf);	//phase angle in radians

+phi1    = (phi*180)/%pi;

+y       = sqrt(3);

+z       =y*pf;

+x	= P/(y*pf);	//VL*IL in VA

+

+//W	= VL*IL*cos(30-phi)

+//VL*IL 	= x;

+W1	= x*cos((30*%pi/180)-(phi1*%pi/180));	//reading of wattemeter in W

+W2	=  x*cos((30*%pi/180)+(phi1*%pi/180));	//reading of wattemeter in W

+

+//result

+mprintf("reading of wattemeter %3.2f W %3.0f W",W1,W2);

+mprintf("\nNote:x value is taken approximate value,so the w1 and w2 differing ")

+mprintf("\nif power factor is leading the readings of wattmeters interchange ");

+

diff --git a/3871/CH7/EX7.18/Ex7_18.sce b/3871/CH7/EX7.18/Ex7_18.sce
new file mode 100644
index 000000000..708fd5d8a
--- /dev/null
+++ b/3871/CH7/EX7.18/Ex7_18.sce
@@ -0,0 +1,25 @@
+//===========================================================================

+//chapter 7 example 18

+

+

+clc;clear all;

+

+//variable declaration

+VL	=400;		//voltage in V

+IL	= 10;		//current in A

+//r	= W1/W2

+//tan(phi)		= sqrt(3)*((W1-W2)/(W1+W2))

+//tan(phi)		= sqrt(3)*((1-(W2/W1))/(1+(W2/W1)))

+//tan(phi)		= sqrt(3)*((1-r)/(1+r))

+//cos(phi)		= 1/sec(phi) = 	1/sqrt(1+(tan(phi)^2) = 1/sqrt(1+(3*((1-r)/(1+r))^2)

+r	= 0.5;

+z       = ((1-r)/(1+r))^2;

+pf	= 1/sqrt(1+(3*z));

+phi	= (acos(pf)*180/%pi);

+W1	= VL*IL*cos((30*%pi/180)-(phi*%pi/180));		//wattmeter reading in W

+W2	= VL*IL*cos((30*%pi/180)+(phi*%pi/180));		//wattmeter reading in W

+

+//result

+mprintf("wattmeter reading = %3.2f W",  W1);

+mprintf("\nwattmeter reading = %3.2f W",W2);

+

diff --git a/3871/CH7/EX7.19/Ex7_19.sce b/3871/CH7/EX7.19/Ex7_19.sce
new file mode 100644
index 000000000..101477de1
--- /dev/null
+++ b/3871/CH7/EX7.19/Ex7_19.sce
@@ -0,0 +1,29 @@
+//===========================================================================

+//chapter 7 example 19

+

+clc;

+clear all;

+

+//variable declaration

+W1	= 3000;		//wattmeter reading in W

+W2	= 1000;		//wattmeter reading in W

+f	= 50;		//frequency in HZ

+V	= 400;		//voltage in V

+

+	

+//calculations

+VP	= V/sqrt(3);	              //voltage in V		

+P	      = W1+W2;		                //input power in kW

+phi	    = atan(((W1-W2)/(W1+W2))*sqrt(3));		            //phase angle in radians

+phi1    = phi*180/%pi;                              //phase angle in degrees

+pf	     =cos(phi1*%pi/180);		                        //power factor lagging

+IL	     = P/((sqrt(3))*V*pf);	                       //line current in A

+ZP	     =VP/IL;		                            //impedance of the circuit per phase in Ω

+R	      = ZP*pf;	                 	//resistance per phase Ω

+XL	     = sqrt((ZP^2 )-(R^2));	              	//reactance per phase in Ω

+L	      = XL/(2*%pi*f);		                 //inducatance per phase in H

+

+//result

+mprintf("resistance per phase = %3.2f Ω",R);

+mprintf("\ninducatance per phase in = %3.3f H",L);

+

diff --git a/3871/CH7/EX7.2/Ex7_2.sce b/3871/CH7/EX7.2/Ex7_2.sce
new file mode 100644
index 000000000..1abd4fcb4
--- /dev/null
+++ b/3871/CH7/EX7.2/Ex7_2.sce
@@ -0,0 +1,30 @@
+//===========================================================================

+//chapter 7 example 2

+

+clc;clear all;

+

+//variable declaration

+x	= 0.004;

+y	= 0.707;		//power factor lagging

+y1	= 0.5;		//power factor lagging

+

+//calculaitons

+theta 	= atan(x)		//theta in degrees

+a	= cos(theta)

+b	= sin(theta)

+phi	= acos(y)

+c	= cos(phi)/(a*cos(theta-phi))	//correction factor 

+A      = cos(phi)/sin(phi);

+e	= (b/(A+b))*100	//percentage error in %

+phi1	= acos(y1) 

+c1	= cos(phi1)/(a*cos(theta-phi1))	//correction factor 

+B     = cos(phi1)/sin(phi1);

+e1	= (b/(B+b))*100		//percentage error in %	

+

+//result

+mprintf("correction factor  when 0.707 pf lagging = %3.3f",c);

+mprintf("\npercentage error =%3.2f percentage ",e);

+mprintf("\ncorrection factor  when 0.707 pf lagging = %3.3f",c1);

+mprintf("\npercentage error =%3.1f percentage ",e1)

+

+

diff --git a/3871/CH7/EX7.20/Ex7_20.sce b/3871/CH7/EX7.20/Ex7_20.sce
new file mode 100644
index 000000000..80a8cbd43
--- /dev/null
+++ b/3871/CH7/EX7.20/Ex7_20.sce
@@ -0,0 +1,25 @@
+//===========================================================================

+//chapter 7 example 20

+

+clc;

+clear all;

+

+//variable declaration

+IPR	= 8;	//current in line R in A

+IPY	= 10;	//current in line Y in A

+IPB	= 6;	//current in line B in A

+VP	=120;	//voltage in V

+pf	= 1;	//power factor

+

+//calculations

+W1	= VP*IPR*pf;	//wattage shown by wattmeter having current coil in line R in watts

+W2	= VP*IPY*pf;	//wattage shown by wattmeter having current coil in line Y in watts

+W3	= VP*IPB*pf;	//wattage shown by wattmeter having current coil in line B in watts

+p	= W1+W2+W3;	//power taken by lighting load in watts

+

+//result

+mprintf("wattage shown by wattmeter having current coil in line R = %3.2f watts",W1);

+mprintf("\nwattage shown by wattmeter having current coil in line Y = %3.2f watts",W2);

+mprintf("\nwattage shown by wattmeter having current coil in line B = %3.2f watts",W3);

+mprintf("\npower taken by lighting load = %3.2f watts",p);

+

diff --git a/3871/CH7/EX7.21/Ex7_21.sce b/3871/CH7/EX7.21/Ex7_21.sce
new file mode 100644
index 000000000..121a5b0e3
--- /dev/null
+++ b/3871/CH7/EX7.21/Ex7_21.sce
@@ -0,0 +1,27 @@
+//===========================================================================

+//chapter 7 example 21

+

+clc;

+clear all;

+

+//variable declaration

+R	= 10;	//resistance in Ω

+XL	= 10;	//reactance  in Ω

+VL	= 440;	//load voltage in V

+

+//calculations

+Z	= sqrt((R^2)+(XL^2));		//impedance of each choking coil in Ω

+VP	= VL/sqrt(3);		//phase voltage in V

+IP	= VP/Z;		//phase current in A

+IL	= IP;		//line current in A

+phi 	= atan(XL/R);	//phase angle in  °

+phi1       = phi*180/%pi;

+

+W1	= VL*IL*cos((30*%pi/180)-(phi1*%pi/180));		//wattmeter reading in W

+W2	= VL*IL*cos((30*%pi/180)+(phi1*%pi/180));		//wattmeter reading in W

+

+//result

+mprintf("line current = %3.2f A",IL);

+mprintf("\nwattmeter reading = %3.2f W",W1);

+mprintf("\nwattmeter reading = %3.2f W",W2);

+

diff --git a/3871/CH7/EX7.22/Ex7_22.sce b/3871/CH7/EX7.22/Ex7_22.sce
new file mode 100644
index 000000000..87b6dd3c5
--- /dev/null
+++ b/3871/CH7/EX7.22/Ex7_22.sce
@@ -0,0 +1,33 @@
+//===========================================================================

+//chapter 7 example 22

+

+clc;

+clear all;

+

+//variable declaration

+W1	= 5000;		//wattmeter reading in W

+W2	= -1000;		//wattmeter reading in W

+VL	= 440;		//load voltage in V

+f	= 50;		//frequency in Hz

+VP      = 440;

+

+//calculations

+P	= W1+W2;		//total power in the load circuit in W

+phi	= atan(((W1-W2)/(W1+W2))*sqrt(3));		//phase angle in °

+phi1        = phi*180/%pi; 

+pf	= cos(phi);		//power factor 

+IP	= P/((sqrt(3)*VL*pf));	//load current per phase in A

+IP1     = IP/sqrt(3);

+ZP	= VP/IP1;			//load impedance per phase 

+RP	= ZP*pf;			//load resistance per phase in Ω

+XP	=ZP*sin(phi);		//load reactance per phase in Ω

+pf1	= 0.5;			//power factor 

+phi2    = (acos(pf1))*180/%pi;

+//reading of wattmeter will be zero

+XP1	= RP*tan((phi2)*%pi/180);		//reactnace in circuit per phase in Ω

+XC	=XP-XP1;			//value of capacitive reactance in troduced in each phase in Ω

+C	= 1/(2*%pi*f*XC);		//value of capacitive reactance introduced in each phase of delta connected in uF

+

+//result

+mprintf("value of capacitive reactance introduced in each phase of delta connected  = %3.0f uF",(C*10^6));

+

diff --git a/3871/CH7/EX7.23/Ex7_23.sce b/3871/CH7/EX7.23/Ex7_23.sce
new file mode 100644
index 000000000..4ec29ab83
--- /dev/null
+++ b/3871/CH7/EX7.23/Ex7_23.sce
@@ -0,0 +1,48 @@
+//================================================================================

+//chapter 7 example 23

+

+clc;

+clear all;

+

+//variable declaration

+VAB1     = 400+0*%i;     //voltage in V

+VBC1    = -200-346.41*%i;     //voltage in V

+VCA1     = -200+346.41*%i;     //voltage in V

+VAB         =400;

+VBC         = 400;

+VCA         = 400;

+TVAB        = 0;

+TVBC        = -120;

+TVCA        =120;

+PAB         = 20000;        //Wwattmetr readig VA

+PBC         = 30000;        //Wwattmetr readig VA

+PCA         = 20000;        //Wwattmetr readig VA

+

+

+//calculations

+IAB        = PAB/VAB;          //magnitude of IABC

+IBC        = PBC/VAB;          //magnitude of IABC

+ICA        = PCA/VAB;          //magnitude of IABC

+c1          = 0;

+c2          = (acos(0.8)*180/%pi);

+c3          = -(acos(0.6)*180/%pi);

+angle1      = c1-TVAB;

+angle2      = c2-TVBC;

+angle3      = c3-TVCA;

+IAB1         = (IAB*cos(angle1))+(IAB*sin(angle1))*%i;

+IBC1         = (IBC*cos(angle2*%pi/180))+(IBC*sin(-angle2*%pi/180))*%i;

+ICA1         = (ICA*cos(angle3*%pi/180))+(ICA*sin(-angle3*%pi/180))*%i;

+IA          = IAB1-ICA1;

+IB          = IBC1-IAB1;

+IC          = ICA1-IBC1;

+W1          = -(VBC1)*IA;

+W2          = VCA1*IB;

+

+

+

+//result

+mprintf("line current IA    = %3.2f %3.2f *j A",real(IA),imag(IA));

+mprintf("\nline current IA    = %3.2f%3.2f*j A",real(IB),imag(IB));

+mprintf("\nline current IA    = %3.2f + %3.2f*j A",real(IC),imag(IC));

+mprintf("\nreading of wattmeter  W1    = %3.2f W",W1);

+mprintf("\nreading of wattmeter  W2    = %3.2f W",W2);

diff --git a/3871/CH7/EX7.24/Ex7_24.sce b/3871/CH7/EX7.24/Ex7_24.sce
new file mode 100644
index 000000000..f378291f5
--- /dev/null
+++ b/3871/CH7/EX7.24/Ex7_24.sce
@@ -0,0 +1,17 @@
+//===========================================================================

+//chapter 7 example 24

+clc;

+clear all;

+

+//variable declaration

+W1	= 2000;		//reading of wattmeter in watts

+W2	= 1000;		//reading of wattmeter in watts

+

+//calculations

+Q	= sqrt(3)*(W1-W2);		//reactive power of the network in V A

+P	= Q/(sqrt(3));		//wattmeter reading when current coil is connected in one phase and the potential coil across the two phases in VA

+

+//result

+mprintf("Wattmeter reading = %3.2f  reactive volt amperes",P);

+

+

diff --git a/3871/CH7/EX7.25/Ex7_25.sce b/3871/CH7/EX7.25/Ex7_25.sce
new file mode 100644
index 000000000..9f1a39531
--- /dev/null
+++ b/3871/CH7/EX7.25/Ex7_25.sce
@@ -0,0 +1,25 @@
+//===========================================================================

+//chapter 7 example 25

+clc;

+clear all;

+

+//variable declaration

+VL	= 415;		//voltage in V

+IL	= 20;		//current in A

+pf	= 0.8;		//phase angle

+

+//calculations

+phi	=acos(pf)		//phase angle in °

+phi1    = (phi*180)/%pi

+x   = cos((30-phi1)*%pi/180)

+W1	= VL*IL*x		//wattmeter reading in W

+W2	= VL*IL*cos((30+phi1)*%pi/180)	//wattmeter reading in W

+//total KVAR = sqrt(3))*(W1-W2)

+// W	= totalKVAR/sqrt(3)

+//W	= (sqrt(3))*(W1-W2))/sqrt(3);		//wattmeter reading

+W	= W1-W2				//wattmeter reading

+

+//result

+mprintf("reading on wattmeter 1 = %3.2d  W",W1);

+mprintf("\nreading on wattmeter 2 = %3.2d  W",W2);

+mprintf("\nreading on wattmeter = %3.2f W",W);

diff --git a/3871/CH7/EX7.3/Ex7_3.sce b/3871/CH7/EX7.3/Ex7_3.sce
new file mode 100644
index 000000000..b30c19bc3
--- /dev/null
+++ b/3871/CH7/EX7.3/Ex7_3.sce
@@ -0,0 +1,31 @@
+//===========================================================================

+//chapter 7 example 3

+

+clc;clear all;

+

+//variable declaration

+V	= 240;		//voltage in V

+I	= 8;		//current in A

+x	= 0.1;		//pf lagging

+Rp	= 8000;		//resistance in Ω

+f	= 50;		//frequency in Hz

+L	= 63.6*10^-3	//inductance 

+

+//calculations

+phi 	= acos(x);

+phi1    =(phi*180)/%pi;

+P	= V*I*x;		//load power

+Pl	= (V^2)/Rp;	//power lost in the pressure coil circuit in watts

+Pt	= P+Pl;		//neglecting inductance of the voltage coil the reading of wattmeter would be in watts

+Xp	= 2*%pi*f*L;	//reactance in  Ω

+theta	= atan(Xp/Rp);

+theta1  = (theta*180)/%pi;

+A = cos(theta1);

+B       =cos(phi1-theta1);

+C   = cos(phi1);

+w	= Pt*(A)*(B/C);	//wattmeter reading 

+e	= ((w-P)/P)*100;		//percentage error in %

+

+//result

+mprintf("phi value in textbook is taken wrong correct is 84°.16 but value is 84°.26 so textbook answer is coming wrong")

+mprintf("\npercentage error in %3.2f percentage ",e);

diff --git a/3871/CH7/EX7.4/Ex7_4.sce b/3871/CH7/EX7.4/Ex7_4.sce
new file mode 100644
index 000000000..beb6261cf
--- /dev/null
+++ b/3871/CH7/EX7.4/Ex7_4.sce
@@ -0,0 +1,42 @@
+//===========================================================================

+//chapter 7 example 4

+

+clc;clear all;

+

+//variable declaration

+w	= 23;		//wattmeter reading in watts

+Rp	= 2000;		//resistance in Ω

+f	= 100;		//frequency in Hz

+L	= 10*10^-3	//inductance 

+V	= 240;		//voltage in V

+I	= 4.5;		//current in A

+

+//calculations

+Xp	= 2*%pi*f*L;	//reactance in  Ω

+theta	= atan(Xp/Rp);

+theta1  =(theta*180)/(%pi)

+//cos(phi)=P/V*I

+//phi 	= acos(P/V*I)

+//w	= Pt*(cos(theta))*(cos(phi-theta))/cos(phi);	//wattmeter reading 

+W1      = V*I;          //V*I in watts

+//phi   = acos(P/W) = acos(P/1080)

+//W     = P*cos(theta)*(cos(phi-theta))/cos(phi)

+//W     =23 =P*cos(0.18)*cos((acos(P/1080))-0.18)/(P/V*I)

+//let cos(acos(P/1080)-0.18) =A

+//B = cos(0.18)

+//W=23  = (P*B*A)/(P/(V*I))

+// W= B*A*V*I

+//A     = W/(B*V*I)

+B      = cos((theta1*%pi)/180); 

+A       = w/(B*V*I);

+//cos(acos(P/1080)-0.18) =A

+//C  =acos(P/1080)   = acos(A)+0.18

+A1      =(acos(A))*(180/%pi);

+C       = A1+0.18

+D       = cos(C*%pi/180)

+P       =1080*D;

+e	= ((w-P)/P)*100;		//percentage error in %

+

+//result

+mprintf("percentage error in %3.2f percentage ",e);

+

diff --git a/3871/CH7/EX7.5/Ex7_5.sce b/3871/CH7/EX7.5/Ex7_5.sce
new file mode 100644
index 000000000..a5ba78d77
--- /dev/null
+++ b/3871/CH7/EX7.5/Ex7_5.sce
@@ -0,0 +1,20 @@
+//===========================================================================

+//chapter 7 example 5

+clc;clear all;

+

+//variable declaration

+f	= 50;		//frequency in Hz

+L	= 5*10^-3	//inductance 

+V	= 100;		//voltage in V

+I	= 10;		//current in A

+R1	= 3000;		//resistance in Ω

+

+//calculations

+x       = ((2*%pi*f*L)/R1);            //tan(theta)

+theta 	= atan(x);	//the angle by which the current in pressure coil lags behind the voltage

+//W = V*I*sin(90+theta) = V*I*cos(theta) = V*I*tan(theta)

+//W=V*I*theta		//since theta is small

+W	= V*I*x;	//reading of wattmeter in watt

+

+//result

+mprintf("error = %3.2f watts",W);

diff --git a/3871/CH7/EX7.6/Ex7_6.sce b/3871/CH7/EX7.6/Ex7_6.sce
new file mode 100644
index 000000000..7c6825183
--- /dev/null
+++ b/3871/CH7/EX7.6/Ex7_6.sce
@@ -0,0 +1,30 @@
+//===========================================================================

+//chapter 7 example 6

+clc;clear all;

+

+//variable declaration

+RL	= 2;	//resistance in Ω

+f	=50;	//frequency in Hz

+L	= 0.25;	//inductance in H

+V	= 200;	//voltage in V

+LP	= 5.6*10^-3;	//inductance in H

+RP  =1000;

+

+//calculations

+XL	= 2*%pi*f*L;	//load reactance in Ω

+ZL	= RL+XL*%i;	//load impedance

+IL	= V/ZL;		//load current in A

+XLP	= 2*%pi*f*LP;	//reactance in Ω

+ZP	= RP+XLP*%i;	//pressure coil circuit impedance in Ω

+IP	= V/ZP;		//pressure coil current in A

+theta	= (atan(imag(IP)/real(IP)))*180/%pi;

+Ic	= IL+IP;

+Ic1     = sqrt(((imag(Ic))^2)+((real(Ic))^2))

+phi  	= (atan(imag(Ic)/real(Ic)))*180/%pi;

+A       = (phi-theta);

+x	= cos((A*%pi)/180);

+y	=cos((theta*%pi)/180);

+W	= V*Ic1*y*x;	//actual reading of wattmeter in watts

+

+//result

+mprintf("actual reading of wattmeter = %3.4f  watts",W);

diff --git a/3871/CH7/EX7.7/Ex7_7.sce b/3871/CH7/EX7.7/Ex7_7.sce
new file mode 100644
index 000000000..f2c868146
--- /dev/null
+++ b/3871/CH7/EX7.7/Ex7_7.sce
@@ -0,0 +1,27 @@
+//===========================================================================

+//chapter 7 example 7

+clc;clear all;

+

+//variable declaration

+V	= 250;		//load voltage in V

+I	= 12;		//load current in A

+Rc	= 0.1;		//resistance in Ω

+Rp	=6500;		//resistance in Ω

+x	= 1;		//pf cos(phi) 

+y	= 0.4;		//pf cos(phi) 

+

+//calculations

+P	= V*I*x;		//power input to the apparatus in W

+PL	= (I^2)*Rc;		//power lost in current coil in W

+e	= (PL/P)*100;	//percentage error in %

+Pc	= (V^2)/Rp;	//power lost in presuure coil in W

+e	= (Pc/P)*100;	//percentage error in %

+P1	= V*I*y;		//power input to the apparatus in W

+PL1	= (I^2)*Rc;		//power lost in current coil in W

+e1	= (PL1/P1)*100;	//percentage error in %

+Pc1	= (V^2)/Rp;	//power lost in presuure coil in W

+e1	= (Pc1/P1)*100;	//percentage error in %

+

+//result

+mprintf("percentage error when pf 1  lagging  %3.2f percentage",e);

+mprintf("\npercentage error when pf 0.4  lagging  %3.2f percentage",e1);

diff --git a/3871/CH7/EX7.8/Ex7_8.sce b/3871/CH7/EX7.8/Ex7_8.sce
new file mode 100644
index 000000000..d7746901c
--- /dev/null
+++ b/3871/CH7/EX7.8/Ex7_8.sce
@@ -0,0 +1,42 @@
+   //============================================================================

+//Chapter 7 Example 8

+

+

+clc;

+clear all;

+

+//variable declaration

+theta1      =1;         //pressure coil phase angle in  °

+theta2      =2;         //pressure coil phase angle in  °

+P1          = 700;          //wattmeter reading in W

+P2          = 620;          //wattmeter reading in W

+V           = 240;          //voltage in V

+

+

+//calculations

+x      = P1/P2;

+//P1        =P*cos(theta2)*cos(phi-theta2)/cos(phi)

+//P2         = P*cos(theta1)*cos(phi-theta1)/cos(phi)

+//P1/P2     = cos(theta2)*cos(phi-theta2)/cos(phi)/cos(theta1)*cos(phi-theta1)/cos(phi)

+//x        = cos(theta2)*cos(phi-theta2)/cos(phi)/cos(theta1)*cos(phi-theta1)/cos(phi)

+//x         = (cos(theta2)/cos(theta1))*(cos(phi-theta2)/cos(phi-theta1))

+//x         = y*(cos(phi-theta2)/cos(phi-theta1))

+//(cos(phi-theta2)/cos(phi-theta1))     = x/y

+y           = (cos(theta2*%pi/180)/cos(theta1*%pi/180));

+z           = x/y;

+//(cos(phi-theta2)/cos(phi-theta1))  = ((cos(thet2*%pi/180))*cos(phi))+(sin(thet2*%pi/180))*sin(phi))/((cos(theta1*%pi/180))*cos(phi))+(sin(thet1*%pi/180))*sin(phi))

+//z     = ((cos(thet2*%pi/180))*cos(phi))+(sin(thet2*%pi/180))*sin(phi))/((cos(theta1*%pi/180))*cos(phi))+(sin(thet1*%pi/180))*sin(phi))

+t           = ((z*cos(theta1*%pi/180))-(cos(theta2*%pi/180)))/((sin(theta2*%pi/180))-(z*sin(theta1*%pi/180)));

+phi         = (atan(t))*180/%pi;

+pf          = cos(phi*%pi/180);

+C           = (phi-theta2)

+c              = cos(C*%pi/180);

+a           = (cos(theta2*%pi/180));

+b           = a*c;

+B           = P1*pf;

+P           = B/b;

+I           = P/(V*pf);

+

+//result

+mprintf("actual power = %3.3f W",P);

+mprintf("\ncurrent drawn = %3.2f A",I);

diff --git a/3871/CH7/EX7.9/Ex7_9.sce b/3871/CH7/EX7.9/Ex7_9.sce
new file mode 100644
index 000000000..97da88e05
--- /dev/null
+++ b/3871/CH7/EX7.9/Ex7_9.sce
@@ -0,0 +1,30 @@
+//===========================================================================

+//chapter 7 example 9

+clc;clear all;

+

+//variable declaration

+Np          = 500;          //number of turns on moving coil 

+Ip          = 0.05;         //current through moving coil in A

+B           = 0.012;           // flux density in the air gap in T

+d           = 0.03;             //diameter in m

+theta1      = 30;

+theta2      = 90;

+x           = 0.866;                //power factor cos(phi) 

+

+//calculations

+

+A       = (%pi/4)*(d^2);            //area  of x-section of moving coilin m^2

+phimax      = B*A;              //maximum flux through moving coil in Wb

+//Mmax        = (phimax*Np)/Ic

+//Mmax*Ic       = X     = phimax*Np

+X        = (phimax*Np);

+//T         = Ip*Ic*Mmax*cos(phi)*sin(theta)

+//T         = Ip*Ic*(X/Ic)*cos(phi)*sin(theta)

+//T         = Ip*(X)*cos(phi)*sin(theta)

+T1           = Ip*X*x*sin(theta1*%pi/180);

+T2           = Ip*X*x*sin(theta2*%pi/180);

+

+//result

+mprintf("torque in when 30° = %3.4e  N-m",T1);

+mprintf("\ntorque in when 90° = %3.4e  N-m",T2);

+