Chapter 18-b Neutral Grounding

Example 18_1 pgno:369

In [6]:
#given
P=2000e3;
V=400;
r=.4;
#solution
z=V**2/(r*P);
print"the value of z= ohm",z

the value of z= ohm 0.2

Example 18_2 pgno:369

In [7]:
#given
w=314;
c=.015e-6;
#solution
l=1/(3*w**2*c);#the difference in result is due to erroneous calculation in textbook.
l=round(l*10)/100;
print"inductance = Henries",l
print"the difference in result is due to erroneous calculation in textbook."

inductance = Henries 22.54
the difference in result is due to erroneous calculation in textbook.

Example 18_3 pgno:369

In [8]:
from math import pi
#given 
c1=1.5e-6;
w=2*pi*50;
L1=1/(3*c1*(w**2));
c2=.9*c1;
L2=1/(3*c2*(w**2));
c3=.95*c1;
L3=1/(3*c3*(w**2));
L1=round(L1*100)/100;
L2=round(L2*10)/10;
L3=round(L3*100)/100;
print"the inductance for 100 percent line capacitance= henries ",L1
print"for 90percent line capacitance,the inductance= henries",L2
print"for 95percent line capacitane inductance= henries",L3

the inductance for 100 percent line capacitance= henries  2.25
for 90percent line capacitance,the inductance= henries 2.5
for 95percent line capacitane inductance= henries 2.37

Example 18_4 pgno:369

In [9]:
#given
from math import pi,sqrt
c=.01e-6*50;
w=2*pi*50;
L=1/(3*c*(w**2));
#solution
L=round(L*100)/100;
V=33e3/sqrt(3);
I=V/(w*L);
I=round(I*1000)/1000;
I=round(I*100)/100;
R=V*I/1e3; #the difference in result is due to erroneous calculation in textbook.
print"the value of L=H and rating =kVA",L,R
print"the difference in result is due to erroneous calculation in textbook."

the value of L=H and rating =kVA 6.75 171.28250436
the difference in result is due to erroneous calculation in textbook.