ABB Relion 670 Series Applications Manual page 297

1MRK 511 401-UUS F
Line
protection
Operate time
Circuit
breaker
Auto-reclosing
function
ANSI04000146 V1 EN-US
Figure 118: 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 circuit breaker pole can be
operated 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-faulted phases.
To maximize the availability of the power system it is possible to choose single-phase tripping and
automatic reclosing during single-phase faults and three-phase tripping and automatic reclosing
during multi-phase faults. Three-phase automatic reclosing can be performed with or without the
use of synchrocheck.
During the single-phase dead time there is an equivalent "series"-fault in the system resulting in a
flow of zero sequence current. It is therefore necessary to coordinate the residual current
protections (ground fault protection) with the single-phase tripping and the auto reclosing
function. Attention shall also be paid to "pole discrepancy" that arises when circuit breakers are
provided with single-phase operating devices. These breakers need pole discrepancy protection.
They must also be coordinated with the single-phase auto recloser and blocked during the dead
time when a normal discrepancy occurs. Alternatively, they should use a trip time longer than the
set single-phase dead time.
Bay control REC670
Application manual
Closed
Open
Break time
Fault duration
Set AR open time
© Copyright 2017 ABB. All rights reserved
Operate
time
Closing time
Fault duration
AR open time for breaker
Reset time
Break time
en04000146_ansi.vsd
Section 14
Control
291