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
autoreclosing open time in such a case by use of an input to PLCLOST, and the setting
parameters. Typical setting in such a case: Extended t1 = On and tExtended t1 = 0.5 s.
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 Extended t1 = Off or On a trip/ start pulse longer than the set time tTrip will
either block the reclosing or extend the auto-reclosing open time. At a setting
somewhat longer than the auto-reclosing open time, this facility will not influence the
reclosing. A typical setting of tTrip could be close to the autoreclosing open time.
tInhibit
, Inhibit resetting delay
A typical setting is tInhibit = 5.0 s to ensure reliable interruption and temporary
blocking of the function. Function will be blocked during this time after the tInhibit
has been activated.
tReclaim
, Reclaim
The Reclaim time sets the time for resetting the function to its original state, after
which a line fault and tripping will be treated as an independent new case with a new
reclosing cycle. One may consider a nominal CB duty cycle of for instance, O-0.3 s
CO- 3 min. – CO. However the 3 minute (180 s) recovery time is usually not critical
as fault levels are mostly lower than rated value and the risk of a new fault within a
short time is negligible. A typical time may be tReclaimt = 60 or 180 s dependent of
the fault level and breaker duty cycle.
StartByCBOpen
The normal setting is Off. It is used when the function is started by protection trip
signals Follow CB = Off. Follow CB = On.
Follow CB
The usual setting is Follow CB = Off. The setting On can be used for delayed reclosing
with long delay, to cover the case when a CB is being manually closed during the
“auto-reclosing open time” before the auto-reclosing function has issued its CB
closing command.
Section 10 1MRK 505 291-UEN A
Control
226
Application manual
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