ABB Relion 670 Series Applications Manual page 305

1MRK 505 370-UUS Rev. K
DeadTime settings
NoOfShots: In power transmission one shot is mostly used. In most cases one auto reclosing shot is
sufficient as the majority of arcing faults will cease after the first auto reclosing shot. In power systems
with many other types of faults caused by other phenomena, for example wind, a greater number of auto
reclosing attempts (shots) can be motivated.
t1 1Ph, t1 2Ph, t1 3Ph: There are separate settings for the first shot for single-, two- and three-phase
auto reclosing dead times.
Single-phase auto reclosing dead time: A typical setting is t1 1Ph = 800ms. Due to the influence of
energized phases the arc extinction may not be instantaneous. In long lines with high voltage the use of
shunt reactors in the form of a star with a neutral reactor improves the arc extinction.
Three-phase auto reclosing dead time: Different local phenomena, such as moisture, salt, pollution, can
influence the required dead time. Some users apply Delayed Auto Reclosing (DAR) with delays of 10s or
more.
Extended t1: The time extension below is controlled by the Extended t1 setting.
tExtended t1: A time extension delay, tExtended t1, can be added to the dead time delay for the first shot.
It is intended to come into use if the communication channel for permissive line protection is lost. The
communication link in a permissive (not strict) line protection scheme, for instance a power line carrier
(PLC) link, may not always be available. If lost, it can result in delayed tripping at one end of a line. There
is a possibility to extend the auto reclosing dead time in such a case by use of the PLCLOST input, and
the tExtended t1 setting. Typical setting in such a case: Extended t1 = Enabled and tExtended t1 = 0.8 s.
t1 3PhHS: There is also a separate time setting facility for three-phase high-speed auto reclosing, t1
3PhHS. This high-speed auto reclosing is activated by the STARTHS input and is used when auto
reclosing is done without the requirement of synchrocheck conditions to be fulfilled. A typical dead time is
400ms.
t2 3Ph, t3 3Ph, t4 3Ph, t5 3Ph: The delay of auto reclosing shot two and possible later shots are usually
set at 30s or more. A check that the circuit breaker duty cycle can manage the selected setting must be
done. The setting can in some cases be restricted by national regulations. For multiple shots the setting
of shots two to five must be longer than the circuit breaker duty cycle time.
MasterSlave settings
Priority: In single circuit breaker applications, one sets Priority = None. At sequential reclosing the auto
recloser for the first circuit breaker, e.g. near the busbar, is set as master (High) and the auto recloser for
the second circuit breaker is set as slave (Low).
tWaitForMaster: The slave should take the duration of the circuit breaker closing time of the master into
consideration before sending the circuit breaker closing command. A setting tWaitForMaster sets a
maximum wait time for the WAIT input to reset. If the wait time expires, the auto reclosing cycle of the
slave is inhibited. The maximum wait time, tWaitForMaster for the second circuit breaker is set longer
than the auto reclosing dead time plus a margin for synchrocheck conditions to be fulfilled for the first
circuit breaker. Typical setting is 2sec.
tSlaveDeadTime: When activating the WAIT input, in the auto recloser set as slave, every dead timer is
changed to the value of setting tSlaveDeadTime and holds back the auto reclosing operation. When the
WAIT input is reset at the time of a successful reclosing of the first circuit breaker, the slave is released to
continue the auto reclosing sequence after the set tSlaveDeadTime. The reason for shortening the time,
for the normal dead timers with the value of tSlaveDeadTime, is to give the slave permission to react
almost immediately when the WAIT input resets. The minimum settable time for tSlaveDeadTime is
Busbar protection REB670
Application manual
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Section 12
Control
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