Application Guide - NP900 Series
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A996A
5.
Circuit breaker is closed and since fault cleared by the Shot1 given non-energized
time, no pick-ups are detected. Close command is drop off after the breaker closed
indication is received and the autorecloser starts to calculate Reclaim time for Shot1.
6.
Reclaim Time for Shot1 is exceeded and the reclosing cycle is ended. AR running,
Shot1 Running and REQ1 Running signals are reset and Reclaim Time for the
Autorecloser application starts. Difference in between of the autoreclosing and shot
specific reclaim times is that if fault is returning in shot specific reclaim time
autorecloser jumps to next shot. If a fault return after successful cycle and
Autoreclosing reclaim time is running recloser will go directly to final trip state and
lock-out state. This behavior can be controlled with settings of the recloser. Both of
these reclaim times can be set to 0 when they are not needed. Recloser function will
skip all timers set to 0. Also is possible to set the AR Reclaim not to be used after
successful reclosing cycle.
7.
Autoreclosing Reclaim Time is exceeded and Autorecloser is set to Ready state
waiting for next request.
3.6.4.9
A
UTORECLOSING IN MESHED OR RING NETWORKS
If the overhead line feeder has distributed power generation, which can arise even more
often in the future since renewable power sources become more common, typical
autoreclosing scheme cannot be applied directly. In this kind of autoreclosing schemes
two end autoreclosing has to be used so that the relays in both ends of the line operate as
master-follower autoreclosing in co-operation. If the reclosing is not applied so that the DG
power plant is disconnected prior to the breaker close command, firstly the reclosing will
fail since the DG power plant will keep the fault on during the dead time of the
autorecloser and also the closing of the breaker when the main grid has been
disconnected from the DG power plant will most probably cause problems for the DG
power plant due to phase shift of the DG power plant during the dead time.
