P44x/EN AP/Hb
MiCOM P40 Agile P442, P444
(AP) 5-
Figure 115: Fault during an autoreclose cycle during (discrimination Time-delay
has not expired)
If the autoreclose logic detects a 3-pole trip (internal or external) on expiry of the
discrimination time-delay, and during the 1P dead time; the single pole autoreclose cycle is
stopped and the relay trips 3-pole and blocks the autorecloser (see Figure 116).
Figure 116: Fault during an autoreclose 1P cycle (discrimination time-delay has
expired)
5.10.1.5 Autoreclose inhibit window
Most circuit breakers are only capable of providing one trip-close-trip cycle. It is necessary to
re-establish sufficient energy in the circuit breaker before the CB can be reclosed. The CB
healthy information from the CB (DDB: 'CB Healthy') is used to ensure that there is sufficient
energy available to close and trip the CB before initiating a CB close command.
If on completion of the dead time (1), the relay does not detect sufficient energy within a
period given by the autoreclose inhibition window (3) – (‘A/R Inhibit Wind’ setting), lockout
will result (4) and the CB will remain open (Blocking Autoreclose, DDB: 'BAR').
If the CB energy becomes healthy again within the time window (2), autoreclosure will occur.
This check can be disabled by not allocating it any opto input. In this case, the DDB cell 'CB
Healthy' is considered invariant in the relay’s logic. This means that the signal is always high
within the relay when the logic requires a high level and at 0 if low level is required. It is an
invariant state for the firmware (same logic is applied for every optional opto input – if not
linked in the PSL these cells are managed as invariant data by the internal logic).
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