Broken Conductor Protection; Equivalent Circuit For A Single-Phase Series Fault - Toshiba GRE110 Instruction Manual

2.7 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. This function is NOT for models 820 and 821.
Figure 2.7.1 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
E
1A
E
1A
Positive phase sequence
Negative phase sequence
Zero phase sequence
E
1A
Figure 2.7.1 Equivalent Circuit for a Single-phase Series Fault
Single-phase series fault
k
1
I
k Z
1F
1 1
I
k Z
2F
2 2
I
k Z
0F
0 0
I
k Z
1F
2
k Z
1 1
K Z
0
I
Z
1
E
1A
 40 
to (1 – k ), k to (1 – k
1 1 2
1– k
1
I
(1-k
1F
I
(1-k
2F
I
(1-k
0F
I
(1-k )Z 1F
2 2 2
(1-k )Z
0
0 0
1F
Z
2
Z
0
6 F 2 T 0 1 7 2
) and k to (1 – k ).
2 0 0
E
1B
)Z
1 1
E
1B
)Z
2 2
)Z
0 0
(1-k )Z
1 1
E
1B
E
1B