Toshiba GRZ100 B Series, Instruction Manual, Page: 82 / 447

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2.4.10 Broken Conductor Protection
Series faults or open circuit faults which do not accompany any earth faults or phase faults are
caused by broken conductors, breaker contact failure, operation of fuses, or false operation of
single-phase switchgear.
Figure 2.4.10.1 shows the sequence network connection diagram in the case of a single-phase
series fault assuming that the positive, negative and zero sequence impedance of the left and right
side system of the fault location is in the ratio of k
1
to (1 – k
1
), k
2
to (1 – k
2
) and k
0
to (1 – k
0
).
Figure 2.4.10.1 Equivalent Circuit for a Single-phase Series Fault
Positive phase sequence
Single-phase series fault
Zero phase sequence
k
2
Z
2
(1-k
2
)Z
2
k
0
Z
0
(1-k
0
)Z
0
E
1A
E
1B
I
1F
I
1F
I
2F
I
2F
I
0F
I
0F
Negative phase sequence
(1-k
1
)Z
1
k
1
Z
1
E
1B
E
1A
k
1
1– k
1
E
1A
E
1B
I
1F
I
1F
(1-k
1
)Z
1
k
1
Z
1
k
2
Z
2
(1-k
2
)Z
2
K
0
Z
0
(1-k
0
)Z
0
E
1A
E
1B
I
1F
Z
1
Z
2
Z
0