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
Summary of Contents for Relion REQ650
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