ABB Relion REQ650, Руководство по применению

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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 performs three-phase automatic-reclosing with single-
shot or multiple-shots.
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.
1MRK 505 291-UEN A
Section 10
Control
199
Application manual