ABB REB670 Applications Manual page 308

Section 12
Control
302
Line
protection
Operate time
Closed
Circuit
breaker
Open
Break time
Fault duration
Auto-reclosing
function
ANSI04000146 V1 EN
Figure 114: Single-shot automatic reclosing at a permanent fault
Single-pole tripping and single-phase automatic reclosing is a way of limiting the effect
of a single-phase line fault on power system operation. Especially at higher voltage levels,
the majority of faults are of single-phase type (around 90%). To maintain system stability
in power systems with limited meshing or parallel routing single phase auto reclosing is
of particular value. During the single phase dead time the system is still capable of
transmitting load on the two healthy phases and the system is still synchronized. It requires
that each phase breaker operates individually, which is usually the case for higher
transmission voltages.
A somewhat longer dead time may be required for single-phase reclosing compared to
high-speed three-phase reclosing. This is due to the influence on the fault arc from the
voltage and the current in the non-tripped phases.
To maximize the availability of the power system it is possible to choose single pole
tripping and automatic reclosing during single-phase faults and three pole tripping and
automatic reclosing during multi-phase faults. Three-phase automatic reclosing can be
Operate
time
Closing time
AR open time for breaker
Set AR open time
1MRK 505 337-UUS -
Break time
Fault duration
Reset time
en04000146_ansi.vsd
Application manual