Application - ABB Relion REC670 Applications Manual

1MRK 511 358-UEN A
13.2.2

Application

Automatic reclosing is a well-established method for the restoration of service in a power
system after a transient line fault. The majority of line faults are flashover arcs, which are
transient by nature. When the power line is switched off by the operation of line protection
and line breakers, the arc de-ionizes and recovers its ability to withstand voltage at a
somewhat variable rate. Thus, a certain dead time with a de-energized line is necessary. Line
service can then be resumed by automatic reclosing of the line breakers. The dead time
selected should be long enough to ensure a high probability of arc de-ionization and
successful reclosing.
For individual line breakers, auto-reclosing equipment, the auto-reclosing open time is used to
determine line "dead time". When simultaneous tripping and reclosing at the two line ends
occurs, auto-reclosing open time is approximately equal to the line "dead time". If the open
time and dead time differ then, the line will be energized until the breakers at both ends have
opened.
Line
protection
Operate time
Closed
Circuit
breaker
Auto-reclosing
function
IEC04000146 V2 EN-US
Figure 97: Single-shot automatic reclosing at a permanent fault
Single-phase 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.
Application manual
Open
Break time
Fault duration
Set AR open time
Operate time
Closing time
Fault duration
AR open time for breaker
Reclaim time
Break time
IEC04000146.vsd
Section 13
Control
M12391-3 v7
239