ABB RELION 650 Series Applications Manual page 224

Section 12
Control
the line dead time. Otherwise these two times may differ as one line end might have a slower
trip than the other end which means that the line will not be dead until both ends have opened.
If the fault is permanent, the line protection will trip again when reclosing is attempted in
order to clear the fault.
It is common to use one automatic reclosing function per line circuit-breaker (CB). When one
CB per line end is used, then there is one auto-reclosing function per line end. If auto-reclosing
functions are included in duplicated line protection, which means two auto-reclosing functions
per CB, one should take measures to avoid uncoordinated reclosing commands. In 1 1/2
breaker, double-breaker and ring bus arrangements, two CBs per line end are operated. One
auto-reclosing function per CB is recommended. Arranged in such a way, sequential reclosing
of the two CBs can be arranged with a priority circuit available in the auto-reclose function. In
case of a permanent fault and unsuccessful reclosing of the first CB, reclosing of the second
CB is cancelled and thus the stress on the power system is limited. Another advantage with the
breaker connected auto-recloser is that checking that the breaker closed before the sequence,
breaker prepared for an auto-reclose sequence and so on. is much simpler.
The auto-reclosing function can be selected to perform single-phase and/or three-phase
automatic-reclosing from several single-shot to multiple-shot reclosing programs. The three-
phase auto-reclosing open time can be set to give either High-Speed Automatic Reclosing
(HSAR) or Delayed Automatic-Reclosing (DAR). These expressions, HSAR and DAR, are mostly
used for three-phase Reclosing as single phase is always high speed to avoid maintaining the
unsymmetrical condition. HSAR usually means a dead time of less than 1 second.
In power transmission systems it is common practise to apply single and/or three phase,
single-shot Auto-Reclosing. In Sub-transmission and Distribution systems tripping and auto-
reclosing are usually three-phase. The mode of automatic-reclosing varies however. Single-
shot and multi-shot are in use. The first shot can have a short delay, HSAR, or a longer delay,
DAR. The second and following reclosing shots have a rather long delay. When multiple shots
are used the dead time must harmonize with the breaker duty-cycle capacity.
Automatic-reclosing is usually started by the line protection and in particular by instantaneous
tripping of such protection. The auto-reclosing function can be inhibited (blocked) when
certain protection functions detecting permanent faults, such as shunt reactor, cable or
busbar protection are in operation. Back-up protection zones indicating faults outside the own
line are also connected to inhibit the Auto-Reclose.
Automatic-reclosing should not be attempted when closing a CB and energizing a line onto a
fault (SOTF), except when multiple-shots are used where shots 2 etc. will be started at SOTF.
Likewise a CB in a multi-breaker busbar arrangement which was not closed when a fault
occurred should not be closed by operation of the Auto-Reclosing function. Auto-Reclosing is
often combined with a release condition from synchrocheck and dead line or dead busbar
check. In order to limit the stress on turbo-generator sets from Auto-Reclosing onto a
permanent fault, one can arrange to combine Auto-Reclosing with a synchrocheck on line
terminals close to such power stations and attempt energizing from the side furthest away
from the power station and perform the synchrocheck at the local end if the energizing was
successful.
Transmission protection systems are usually sub-divided and provided with two redundant
protection IEDs. In such systems it is common to provide auto-reclosing in only one of the sub-
systems as the requirement is for fault clearance and a failure to reclose because of the auto-
recloser being out of service is not considered a major disturbance. If two auto-reclosers are
provided on the same breaker, the application must be carefully checked and normally one
must be the master and be connected to inhibit the other auto-recloser if it has started. This
inhibit can for example be done from Autorecloser for 3-phase operation(SMBRREC) In
progress.
When Single and/or three phase auto-reclosing is considered, there are a number of cases
where the tripping shall be three phase anyway. For example:
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1MRK 505 363-UEN A
Application manual