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When [VCHK] is set to "SYN, a three-phase autoreclose is performed with the synchronism check
only.
When [VCHK] is set to "OFF", three-phase autoreclose is performed without voltage and
synchronism check.
The voltage and synchronism check requires a single-phase voltage from the busbar and the line as
a reference voltage. User can select one reference voltage from A phase, B phase, C phase, A-B
phase, B-C phase and C-A phase by the scheme switch [APPL-VTS].
Permanent fault
When reclose-onto-a-fault is activated, when a permanent fault exists, three-phase final tripping is
performed. However, this operation is performed only in the single-shot autoreclose mode. In the
multi-shot autoreclose mode, reclosing is retried as described below.
Note: The SOTF (Switch-on-to-fault) function is required to be programmed by PLC function,
because the DOC element cannot operate when the above fault is a fault such as a three-phase
close-up fault.
Two- to five shot autoreclose
Multi-shot autoreclose can be executed up to four times after the first-shot autoreclose fails. Figure
2.5.3 shows the simplified scheme logic for the multi-shot autoreclose of the second to fifth shot.
The multi-shot mode, two to five shots, is set with the scheme switch [ARC∗-NUM].
In low-speed autoreclose, the dead time counter T1S2 or T2S2 for the second shot is activated if
the first shot autoreclose is performed, but tripping occurs again. Second shot autoreclose is
performed only when the voltage and synchronism check element operates (VCHK = 1) after a
period of time set on the T1S2 or T2S2 has elapsed. At this time, outputs of the step counter are:
SP1 = 1, SP2 = 0, SP3 = 0, SP4 = 0 and SP5 = 0.
Autoreclose is completed at this step if the two shots mode is selected for the multi-shot mode.
Therefore, the tripping following the "reclose-onto-a-fault" becomes the final tripping (ARC FT =
1).
If the voltage and synchronism check element does not operate within the period of time set on the
timer T1S2R or T2S2R which is started at the same time as T1S2 is started, the multi-shot
autoreclose is cancelled (ARC FT = 1).
When the three shots mode is selected for the multi-shot mode, autoreclose is further retried after
the above tripping occurs. At this time, the T1S3 and T1S3R, or T2S3 and T2S3R are started. The
third shot autoreclose is performed only when the voltage and synchronism check element
operates after the period of time set on the T1S3 or T2S3 has elapsed. At this time, outputs of the
step counter are: SP1 = 0, SP2 = 1, SP3 = 0, SP4 = 0 and SP5 = 0.
The three shots mode of autoreclose is then completed. Therefore, the tripping following the
"reclose-onto-a-fault" becomes the final tripping (ARC FT = 1).
If the voltage and synchronism check element does not function within the period of time set on
the T1S3R or T2S3R, multi-shot autoreclose is cancelled.
When the four or five shot autoreclose is selected, autoreclose is further retried once again for
tripping that occurs after the "reclose-onto-a-fault". This functions in the same manner as the three
shot autoreclose.
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