This document describes an experiment to model the short circuit currents of a three phase alternator. It defines constants for reactances and time constants, and calculates steady state and transient short circuit currents using those values in a MATLAB simulation. The simulation plots the short circuit current over time, showing the subtransient, transient, and steady state currents.

1. EXPERIMENT – 3
OBJECT: - To obtain steady state transient and sub transient short circuit currents of a three
phase alternator.
CODE:- clc;
clear all;
f=50;
w=2*pi*f;
Xd1=0.5;
Xd2=0.4;
Xd=1.2;
E=1.0;
delta=0;
Td1=0.35;
Td2=1.0;
id2=(sqrt(2)*E)/Xd2
id1=(sqrt(2)*E)/Xd1
id=(sqrt(2)*E)/Xd
for t=0:0.0001:1
i=sqrt(2)*E*((1/Xd2-1/Xd1)*exp(-t/Td2)+(1/Xd1-1/Xd)*exp(-t/Td1)+(1/Xd))*sin(w*t+delta);
hold all
plot(t,i)
end
xlabel(' t(sec) ')

2. ylabel('i(amp)')
RESULT :- id2 =3.5355 , id1 =2.8284 , id =1.1785
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
-4
-3
-2
-1
0
1
2
3
4
t(sec)
i(amp)