ABB Relion REC670 Applications Manual page 260

Section 13
Control
Operation
The operation of the Autorecloser for 1/2/3-phase operation (SMBRREC) function can be
switched
external switch via IO or communication ports.
NoOfShots , Number of reclosing shots
In power transmission 1 shot is mostly used. In most cases one reclosing shot is sufficient as
the majority of arcing faults will cease after the first reclosing shot. In power systems with
many other types of faults caused by other phenomena, for example wind, a greater number of
reclose attempts (shots) can be motivated.
First shot and reclosing program
There are six different possibilities in the selection of reclosing programs. The type of
reclosing used for different kinds of faults depends on the power system configuration and
the users practices and preferences. When the circuit-breakers only have three-phase
operation, then three-phase reclosing has to be chosen. This is usually the case in
subtransmission and distribution lines. Three-phase tripping and reclosing for all types of
faults is also widely accepted in completely meshed power systems. In transmission systems
with few parallel circuits, single-phase reclosing for single-phase faults is an attractive
alternative for maintaining service and system stability.
Auto-reclosing open times, dead times
Single-phase auto-reclosing time: A typical setting is
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 shot 1 delay: For three-phase High-Speed Auto-Reclosing (HSAR) a typical open
time is 400ms. 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. The delay of reclosing shot 2 and possible later shots are usually set at 30s or more. A
check that the CB 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 2-5
must be longer than the circuit breaker duty cycle time.
Extended t1 and tExtended t1 , Extended auto-reclosing open time for shot 1.
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 open time in
such a case by use of an input to PLCLOST, and the setting parameters. Typical setting in such
a case:
tSync , Maximum wait time for synchronizationcheck
The time window should be coordinated with the operate time and other settings of the
synchronization check function. Attention should also be paid to the possibility of a power
swing when reclosing after a line fault. Too short a time may prevent a potentially successful
reclosing.
tTrip , Long trip pulse
Usually the trip command and start auto-reclosing signal reset quickly as the fault is cleared. A
prolonged trip command may depend on a CB failing to clear the fault. A trip signal present
when the CB is reclosed will result in a new trip. Depending on the setting
On a trip/start pulse longer than the
auto-reclosing open time. A trip pulse longer than the set time
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On and Off . The setting ExternalCtrl makes it possible to switch it On or Off using an
Extended t1 = On and tExtended t1 = 0.8 s .
t1 1Ph = 800ms . Due to the influence of
set time tTrip will either block the reclosing or extend the
1MRK 511 358-UEN A
Extended t1 = Off or
tTrip will inhibit the reclosing.
Application manual
M12399-97 v8