6 files changed, 167 insertions, 0 deletions
diff --git a/3731/CH4/EX4.1/Ex4_1.sce b/3731/CH4/EX4.1/Ex4_1.sce
new file mode 100644
index 000000000..152d1bea0
--- /dev/null
+++ b/3731/CH4/EX4.1/Ex4_1.sce
@@ -0,0 +1,21 @@
+//Chapter 4: Selection of Motor Power Rating
+//Example 1
+clc;
+
+//Variable Initialization
+t_min=40       // Minimum Temperature Rise in degree Celsius
+t_ri=15          // Temperature Rise in degree Celsius
+t_cl=10          // Clutched Time in sec
+t_de=20          // Declutched Time in sec
+k= 60           // Heating and Cooling time constant  
+
+//Solution
+
+x=exp(-t_de/k)
+y=exp(-t_cl/k)
+
+th2= (t_min-t_ri*(1-x))/x       //as t_min=t_ri(1-x)+th2*x
+th_s=(th2-t_min*y)/(1-y)   //as th2=th_s(1-y)+t_min*y
+
+mprintf("Maximum temperature during the duty cycle :%.1f °C",th2)
+mprintf("\n Temperature when the load is clutched continuously :%.1f °C",th_s)
diff --git a/3731/CH4/EX4.2/Ex4_2.sce b/3731/CH4/EX4.2/Ex4_2.sce
new file mode 100644
index 000000000..70bb33566
--- /dev/null
+++ b/3731/CH4/EX4.2/Ex4_2.sce
@@ -0,0 +1,42 @@
+//Chapter 4: Selection of Motor Power Rating
+//Example 2
+clc;
+
+//Variable Initialization
+N=200         //Speed in rpm
+Tc=25000      //Constant Torque in N-m
+J=10000       //Moment of inertia  in Kg-m2
+
+//Given Duty Cycles
+t1=10         //For full speed and at constant torque
+t2=1          //For no load at full speed
+t3=5          //For speed reversal from N to -N
+t4=1          //For no load  at full speed
+T5=20000      //Torque in N-m
+t5=15         //At full speed and at a torque T1
+t6=1          //For no operation at full speed
+t7=5          //For speed reversal from -N to N
+t8=1          //For no load operation
+
+
+//Solution
+
+Tr=J*(N-(-N))*2*%pi/60/5   //Reversal torque
+x=Tc**2*t1+Tr**2*t3+T5**2*t5+Tr**2*t7
+t=t1+t2+t3+t4+t5+t6+t7+t8      //Total Time
+Trms=sqrt(x/t)            //rms torque
+
+Trated=Trms              //Rated torque is equal to the rms torque
+Pr=Trated*2*%pi*200/60    //Power rating
+r=Tr/Trms            //Ratio of reversal torque to the rms torque
+Pr=Pr*1e-3
+
+mprintf("Torque of motor is :%d N-m",Trms)
+
+if r < 2 then
+disp("Trms is rated equal to the Motor")
+mprintf(" Trms=%d N-m\n",Trms)
+end
+
+mprintf(" Power rating :%.3f kW",Pr) 
+//The answer provided in the textbook is wrong
diff --git a/3731/CH4/EX4.3/Ex4_3.sce b/3731/CH4/EX4.3/Ex4_3.sce
new file mode 100644
index 000000000..82c0b9682
--- /dev/null
+++ b/3731/CH4/EX4.3/Ex4_3.sce
@@ -0,0 +1,28 @@
+//Chapter 4: Selection of Motor Power Rating
+//Example 3
+clc;
+
+//Variable Initialization
+P1=400     //load in kW
+P2=500     //load in KW
+Pmax=P2
+
+//Duty Cycles in minutes
+t1=5       //load rising from 0 to P1 
+t2=5       //uniform load of P2 
+t3=4       //regenerative power equal to P1
+t4=2       //motor remains idle
+
+//Solution
+deff('y=f(x)','y=(400/5*x)**2')
+I=intg(0,5,f)
+P11=sqrt(I/t1)
+x=P11**2*t1+P2**2*t2+P1**2*t3
+t=t1+t2+t3+t4    //total time
+Prms=sqrt(x/t)
+
+y=2*Prms
+if P2<y then
+    mprintf(" Hence Pmax:%d kW is less than twice Prms:%.1f kW",Pmax,2*Prms)
+end
+mprintf("\n Hence Motor rating is: %d kW\n",Prms)
diff --git a/3731/CH4/EX4.4/Ex4_4.sce b/3731/CH4/EX4.4/Ex4_4.sce
new file mode 100644
index 000000000..532a31e96
--- /dev/null
+++ b/3731/CH4/EX4.4/Ex4_4.sce
@@ -0,0 +1,30 @@
+//Chapter 4: Selection of Motor Power Rating
+//Example 4
+clc;
+
+//Variable Initialization
+Cr=60      //Heating time constant in minutes
+Cs=90      //Cooling time constant in minutes
+P=20       //Full load in kW
+
+//Solution
+
+//Part-i
+a=0  
+tr=10    //Time  to deliver in minutes
+x=exp(-tr/Cr)
+K=sqrt(1/(1-x))
+P1=K*P  //Permitted load
+
+//Part-ii
+a=0 
+tr=10   //Intermittent load period allowed in minutes
+ts=10   //Shutdown time period in minutes
+x=exp(-(tr/Cr+ts/Cs))
+y=exp(-tr/Cr)
+K=sqrt((1-x)/(1-y))
+P2=K*P  //Permitted load
+
+
+mprintf("\ni)Required permitted load:%d kW",P1)
+mprintf("\nii)Required permitted load:%.2f kW",P2)
diff --git a/3731/CH4/EX4.5/Ex4_5.sce b/3731/CH4/EX4.5/Ex4_5.sce
new file mode 100644
index 000000000..98e1856d5
--- /dev/null
+++ b/3731/CH4/EX4.5/Ex4_5.sce
@@ -0,0 +1,16 @@
+//Chapter 4: Selection of Motor Power Rating
+//Example 5
+clc;
+
+//Variable Initialization
+P=100     //Half hour rating of the motor
+Cr=80     //Heating time constant in minutes
+n=0.7     //Maximum efficiency at full load
+
+//Solution
+
+Pcu=n**2   //Coppper loss
+a=Pcu
+K=sqrt((1+a)/(1-%e**(-30/Cr))-a)  
+Pco=P/K     
+mprintf("Therefore the continuous rating is:%.2f kW",Pco)
diff --git a/3731/CH4/EX4.6/Ex4_6.sce b/3731/CH4/EX4.6/Ex4_6.sce
new file mode 100644
index 000000000..01954b05b
--- /dev/null
+++ b/3731/CH4/EX4.6/Ex4_6.sce
@@ -0,0 +1,30 @@
+//Chapter 4: Selection of Motor Power Rating
+//Example 6
+clc;
+
+//Variable Initialization
+I=500       //Eated Armature Current in A
+Ra=0.01     //Armature Resistance in ohm
+P=1000      //Core Loss in W
+B=0.5       
+
+//Duty Cycles
+tst=10       //Given Interval for accelaration at twice the rated current
+tr=10        //Given Interval for running at full load 
+tb=10        //Given Interval for deceleration at twice the rated armature current
+
+//Solution
+
+Es=tst*(2*I)**2*Ra+P
+Eb=Es
+p1s_tr=(I**2*Ra+P)*tr
+p1r=I**2*Ra+P
+gamma=(1+B)/2
+x=(Es+p1s_tr+Eb)/p1r
+y=gamma*tst+tr+gamma*tb
+ts=(x-y)/B               //Idling interval
+
+fmax=3600/(tst+tr+tb+ts) //Maximum Frequency of drive operation   
+
+mprintf("\nMaximum Frequency of drive operation = %.2f per hour",fmax)
+//The answer provided in the textbook is wrong