Toshiba GR-200 Series Instruction Manual page 257

TRC function. If an external relay can generate an 'ARC_START' signal,
can adopt it by programing the binary input circuit (BI) in the PLC function.
'TREADY' Reclaim Timer
(xiii)
Certain considerations are required to ensure that the ARC function is ready for the next cycle
of operation; the reclaim timer 'TREADY' is provided within the ARC function to accommodate
this requirement. When a CB is closed for the first time subsequent to the maintenance of a
distribution line, the closure would normally be expected to be successful (that is, the CB is
closed on to a healthy line). Then the minimum time setting of the [TREADY] reclaim timer
should be longer than the time required to judge that the CB has closed successfully.
Another consideration required for this setting is that after the CB has gone through a
successful ARC cycle; the maximum allowable successive close-open operations are achieved
with the setting. In this case, the minimum time delay required before the CB is ready for the
next ARC cycle becomes the setting criteria for the [TREADY] timer.
Where the incidence of recurrent lightning strikes is experienced, a shorter reclaim time
will prevent the ARC function going into an unnecessary lock out. On the other hand, caution
is required when considering the exposure of the CB to an excessive number of ARC cycles
caused by recurrent faults that will result in an increase in the frequency of the maintenance
cycle.
In summary, the time required for the CB to be ready for the next cycle of ARC is the
minimum setting that can be applied to the reclaim timer [TREADY] in the ARC function. The
criteria for setting the reclaim timer is described in the Application Guidelines in Chapter
2.22.8 and includes the setting example under 2.22.8(ii)-3.
Function block diagram
2.22.3
The 'ARC_START' signal is initiated by the 'GEN.TRIP' signal from the TRC; issue of 'ARC
SHOT1' and others is enabled by the permissive 'ARC-VCHK' signal. Figure 2.22-2 illustrates
the outline of the ARC function. If the multi-shot scheme ('ARC SHOT1' and 'ARC SHOT2)' is
required for the fault, the signals 'CB_ALLPH_CLOSE' and 'CB-ARC READY' are required to
issue an 'ARC READY' signal. The overall logic is grouped into seven internal logic blocks: (i).
Start-up, (ii). Initiation, (iii). SHOT1, (iv). SHOT2, (v). Issuing command, (vi). Success check,
and (vii). Shot counter. Their respective logic blocks are mutually connected. Issue of either
the 'ARC SHOT1' signal or the 'ARC SHOT2' signal generates the CB, 'ARC CLOSE
COMMAND'. Note that for simplicity Figure 2.22-2 is drawn as a guide to illustrate a two-shot
example of a multi-shot scheme but the multi-shot scheme is capable of issuing up to five shots.
Thus, setting S2 for [ARC-NUM] results in the scheme depicted in Figure 2.22-2, hence three
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6F2T0200 (0.15)
the user
GRE200 (1,2)