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Equivalent circuit for a one-phase series fault
2.8.1
Figure 2.8-1 shows the sequence diagram of the network connection when a single-phase series
fault occurs. We can represent the series fault by the positive sequence, negative sequence and
zero sequence impedances; the impedances are distributed to the left and right as shown in
the diagram of the primary circuit below. The ratio of the left to the right is determined by the
fault location such as k1:1-k1, k2:1-k2, and k0:1-k0.
E
Positive sequence
Negative sequence
Zero sequence
E
Figure 2.8-1 Equivalent circuit for a single-phase fault
The series fault results in positive sequence current (I
and zero phase sequence current (I
where,
E
, E
: power source voltage
1A
1B
Z
:
positive sequence impedance
1
Z
:
negative sequence impedance
2
Z
:
zero sequence impedance
0
E
Series or open circuit fault
1A
k
1
I
1F
k
Z
1
1
1A
k
Z
I
2
2
2F
I
k
Z
0F
0
0
I
k
Z
1F
k
1
1
K
1A
Z
1
E
1A
) in the single-phase. These are given by
0F
��
+ ��
1��
2��
��
��
2��
2��
��
∙ ��
= ��
1��
1��
- 117 -
1– k1
I
1F
(1-k
)Z
1
1
I
(1-k
)Z
2F
2
2
I
(1-k
)Z
0F
0
0
(1-k
(1-k
)Z
Z
2
2
2
2
(1-k
)Z
Z
0
0
0
0
I
Z
2
1F
E
Z
0
), negative sequence current (I
1F
+ ��
= 0
0��
∙ ��
��
= 0
0��
0��
��
∙ ��
��
1��
1��
2��
2��
6F2T0207 (0.01)
E
1B
E
1B
)Z
1
1
E
1B
1B
(2.8-1)
(2.8-2)
(2.8-3)
GRE200 (5,6)
)
2F
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