Autoreclose Operating Sequence; Ar Timing Sequence - Transient Fault; Ar Timing Sequence - Evolving/Permanent Fault; Figure 132: Autoreclose Sequence For A Transient Fault - GE MiCOM P40 Technical Manual

Chapter 11 - Autoreclose
3.4

AUTORECLOSE OPERATING SEQUENCE

The Autoreclose sequence is controlled by so-called Dead Timers. Dead Time Control settings are used to select
the conditions that initiate Dead Timers in the Autoreclose sequence (for example protection operate, protection
reset, CB open, etc.). This section describes typical AR operation sequences in which Dead Timers start when
protection operation resets.
Note:
In a multi-shot AR sequence, a number of Dead Timers are used (one for each shot). All Dead Timers are enabled when the
sequence is initiated, but each timer only starts when the particular shot with which it is associated is triggered.
3.4.1

AR TIMING SEQUENCE - TRANSIENT FAULT

The figure below describes the operating sequence for a single-shot Autorecloser for a transient fault that clears
when the faulted line is isolated.
Protection Trip
AR in Progress
CB Open
Dead Time
Auto -close
Reclaim Time
Successful Autoreclose
V03395

Figure 132: Autoreclose sequence for a Transient Fault

Following fault inception, the protection operates and issues a trip signal. At the same time the Autoreclose in
Progress signal is asserted. Shortly afterwards the circuit breaker will open as indicated by the CB Open signal.
Opening of the CB clears the fault and the protection resets. When this happens, the Dead Timer is started and the
output remains high until the Dead Time setting expires, whereupon it resets and the Autorecloser issues the Auto-
close command to close the circuit breaker. As the fault has been cleared, the circuit breaker closes and remains
closed. When the Auto-close pulse is removed, the Reclaim Timer starts. If no further fault is detected before the
Reclaim Timer expires, the Autoreclose is considered to be successful and this is indicated by the Successful
Autoreclose signal.
3.4.2

AR TIMING SEQUENCE - EVOLVING/PERMANENT FAULT

The figure below shows a single-shot AR operating sequence where the fault is not cleared by the first AR cycle.
The sequence starts in a similar way to that of a transient fault, but in this case the fault is not transient (it may be
permanent, or it may evolve into a fault involving more than one phase). This case shows an evolving fault
inception occurring before the Reclaim Time has expired. When the Autorecloser recognises that the protection
has tripped, the cycle is terminated. The Autorecloser goes into Lockout, and the Autoreclose in Progress signal is
reset.
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