Module 3 : Sequence Components and Fault Analysis
Lecture 10 : Sequence Components
10.5
Fault Current Calculation in Sequence Domain (contd..)
Since for SLG fault at phase 'a'
we can add equations 11, 12 and 13. In addition when we invoke the condition that I
0
= I
1
= I
2
= I
a
/3 we get,
The SLG fault can be visualized by a series connection of positive, negative and zero sequence networks with three times the fault impedance.
The positive sequence, negative sequence and Zero sequence fault currents are given by following equations.
(Solid Fault)
(Fault through impedance Z
f
)
On similar lines following equations can be derived for LL and LLG faults.
LL fault:
The Zero Sequence Data is not required for this fault.
(solid fault)
(fault through impedance Z
f
)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
we can add equations 11, 12 and 13. In addition when we invoke the condition that I0 = I1 = I2 = Ia/3 we get,
(Solid Fault)
(Fault through impedance Zf) 
(fault through impedance Zf) 
