When one or two phases of a balanced three-phase line opens it creates an unbalance in the
system and results in the flow of unbalanced currents. Such conditions occur in the system when
one or two conductors of a trnansmission line are broken due to storm or if fuses, isolators or
circuit breakers operate only on one or two phases leaving others connected. Such open conductor
faults can also be analysed with the help of [¯ZBus] matrices of sequence networks.