ABB Relion 670 Series Applications Manual page 293

1MRK 511 358-UUS A
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-pole 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 WYE 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.
and , 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:
tExtended t1 = 0.8 s .
and
tSync , Maximum wait time for synchronismcheck
The time window should be coordinated with the operate time and other settings of the
synchronism 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 initiate 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
initiate pulse longer than the
reclosing open time. A trip pulse longer than the set time
setting somewhat longer than the auto-reclosing open time, this facility will not influence the
reclosing. A typical setting of
tInhibit , Inhibit resetting delay
A typical setting is
function. Function will be blocked during this time after the
Application manual
set time tTrip will either block the reclosing or extend the auto-
tTrip could be close to the auto-reclosing open time.
tInhibit = 5.0 s to ensure reliable interruption and temporary blocking of the
t1 1Ph = 800ms . Due to the influence of
Extended t1 = Off or On a trip/
tTrip will inhibit the reclosing. At a
tinhibit has been activated.
Section 13
Control
Extended t1 = On
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