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2.5 Autoreclose
The GRD150 model 300 and 400 series provide two-stage and multi-shot (five shots)
autoreclosing scheme and are applied for one-circuit breaker:
• Two-stage autoreclosing scheme (ARC1, ARC2)
• Single phase or three phase autoreclosing scheme for the first shot
• Three phase autoreclosing scheme for the second to fifth shot
• Integrated synchronism check function for autoreclosing
• A utoreclosing counter
The autoreclosing can be initialized by OC1 to OC4, EF1 to EF4, SEF1 to SEF4, DOC1 to DOC4,
DEF1 to DEF4, DSEF1 to DSEF4 trip signals or external trip signals which are set by scheme
switches [∗∗∗∗-INIT] or PLC function. When a trip signal is not used, is used for ARC1, and used
for ARC2, set [∗∗∗∗-INIT] to "NA", "ARC1" and "ARC2" respectively. If a trip signal is used to
block the autoreclose, set [∗∗∗∗-INIT] to "BLK".
The GRD150 model 300 and 400 series also provide the manual close function. For the manual
close function, refer to Section 2.6.3.
2.5.1
Autoreclosing Scheme
Two-stage autoreclosing ARC1 and ARC2 are provided. The scheme logic of both schemes are
same. When the different setting against a phase fault and an earth fault is required for the dead
time setting, for instance, the ARC1 for phase fault and the ARC2 for earth fault is applied.
First-shot autoreclose
Three types of first-shot autoreclose modes are provided: three-phase autoreclose, single-phase
autoreclose, and user configurable autoreclose. An optimal mode is selected by the autoreclose
mode selection switch [ARCEN], [ARCEN-S] and [ARCEN-C]. When autoreclose is disabled, all
switches above are set to "Off".
Three-phase autoreclose:
In this autoreclose mode, three phases are tripped, and then reclosed regardless of the fault mode,
whether single-phase fault or multi-phase fault. A shorter dead time can be set in this mode when
compared to the single-phase autoreclose. For the three-phase autoreclose, synchronism check and
voltage check between the busbar and the line are required. The voltage condition is set by PLC
function.
This reclosing mode is simply expressed as "T" in the following descriptions.
Single-phase autoreclose:
In this mode, only the faulty phase is tripped, and then reclosed if a single-phase earth fault occurs.
Since power can be transmitted through healthy phases even during dead time, this mode is
convenient for maintaining power system stability. On the other hand, the capacitive coupling
effect between the healthy phase and faulty phase may cause a longer de-ionization time when
compared to a three-phase autoreclose. As a result, a longer dead time is required.
In case of a multi-phase fault, three phases are tripped, but reclosing is not made.
For single-phase autoreclose, each phase of the circuit breaker must be segregated.
This reclosing mode is simply expressed as "S" in the following descriptions.
⎯
⎯
95
6 F 2 S 0 8 4 2
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