Broken Conductor Protection - Toshiba GRL100-701B Instruction Manual

2.10 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 2.10.1 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
k ).
0
E
1A
E
1A
Positive phase sequence
Negative phase sequence
Zero phase sequence
E
1A
Single-phase series fault
k
1
k Z
I
1 1
k Z
2 2
k Z
I
0 0
I
1F
k Z
1 1
Z
1
E
1A
Figure 2.10.1 Equivalent Circuit for a Single-phase Series Fault
 101 
to (1 – k
1
I
1F 1F
I I
2F 2F
I
0F
0F
k Z (1-k )Z
2 2 2 2
K Z (1-k )Z
0 0
0 0
I
Z
1F
2
Z
0
6 F 2 S 0 8 5 0
), k to (1 – k ) and k
1 2 2
E
1B
1– k
1
(1-k )Z
1 1
E
(1-k )Z
2 2
(1-k )Z
0 0
I
1F
(1-k )Z
1 1
E
E
1B
to (1 –
0
1B
1B