Chapter 32 Protection of Transformers

Example 32_1 pgno:600

In [1]:
v1=33e3;
v2=6.6e3;
i1=300;
from math import sqrt
trn=sqrt(3);
i2=i1*v2/v1;
ratio=300/5;
i1sec=i1/ratio;
i1sec=round(i1sec*100/trn)/100;
print"Ct ratio on HT side = i2:(i1sec)",i2,i1sec

Ct ratio on HT side = i2:(i1sec) 60.0 2.89

Example 32_2 pgno:601

In [2]:
from math import sqrt
r=30e6;
v=11.5e3;
v2=69e3;
ip=r/(sqrt(3)*v);
ip=round(ip);
ratio=3000/5;
iS=ip/ratio;
iS=sqrt(3)*iS;
iS=round(iS*100)/100;
print"at LV side secondry current iS=A\t Ip=\t",iS,ip
ipn=r/(sqrt(3)*v2);
Ct=ipn/iS;
ct=round(Ct/10)*10;
iS=5;
ip=iS*ct;
print"\nSecondary current=A\tat HV side CT ratio=:\t primarry current IpA\t",iS,ct*iS,iS,ip

at LV side secondry current iS=A	 Ip=	4.35 1506.0

Secondary current=A	at HV side CT ratio=:	 primarry current IpA	5 300.0 5 300.0