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2.34.4 Timing diagram
(i) Single shot scheme for an Arcing fault (Shot1 for CB#1 and
successful operation in TPAR mode)
Figure 2.34-6 illustrates an example for which the single shot scheme has been selected (i.e.
[ARCNUM]=S1); an arcing fault is cleared following the operation of the protection relay and
the issue of the ‘GEN.TRIP-A/B/C’ signals for the tripping of the CB#1. The ‘GEN.TRIP-A/B/C’
also initiates the ARC function and an ‘ARC1 CLOSE COMMAND’ signal is issued following
the expiration of the dead time set for [TTPAR1]. When On is set for [ARC-SucChk], this
scheme will determine that the ARC1 was successful when the ‘CB1 ALLPH CLOSE’ signal is
detected following the issuing of the ‘ARC1 CLOSE COMMAND’ signal; the operation of the
ARC function is reset if it operates successfully (i.e., the ‘ARC1 IN-PROG’ signal is turned off).
Figure 2.34-6 Single shot scheme [ARC-NUM]=S1 for an Arcing fault; operation is successful
Note: The permissive signal ‘ARC1-VCHK’ is required in the TPAR mode, but is omitted
here for the sake of clarity. The pulse width of the ‘ARC1 CLOSE COMMAND’
signal is defined using the setting [TCCW1].
(ii) Single shot scheme for an Arcing fault; CB#1 fails to reclose
Figure 2.34-7 also shows the single shot scheme. However, the CB#1 fails to reclose on
receiving the ‘ARC1 CLOSE COMMAND’ so that the ARC function initiates the ‘ARC1 CLOSE
FAIL’ signal within the setting time [TARCDSUC]. Consequently, the ARC function goes to the
final trip (ARC1 FT) stage so that the ARC will not issue another ‘ARC1 CLOSE COMMAND’
signal hereafter.
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