P54x/EN OP/La4 Operation
(OP) 5-140
MiCOM P543, P544, P545 & P546
OP
Every time the relay trips the sequence counter is incremented by 1. The relay compares
the Single Pole Shots and Three Pole Shots counter values to the sequence count. If the
fault is single phase and the sequence count is greater than the Single Pole Shots setting
then the relay will lockout. If the fault is multi-phase phase and the sequence count is
greater than the Three Pole Shots setting then the relay will also lockout.
For example, if Single Pole Shots = 2 and Three Pole Shots = 1, after two phase-phase
faults the relay will lockout because the sequence count = 2 which is greater than the Three
Pole Shots target of 1 and the second fault was a multi-phase fault. If there was a
permanent earth fault the relay would trip and reclose twice and on the third application of
earth fault current it would lockout. This is because on the third application of fault current
the sequence count would be greater than the Single Pole Shots target of 2 and the third
fault was an earth fault. There is no lockout at the second trip because the second trip was
single phase and the sequence count is not greater than the Single Pole Shots target of 2.
If there was a single phase fault which evolved to a phase-phase-ground fault then the relay
would trip and reclose and on the second multi-phase fault would lockout. This is because
on the second application of fault current the sequence count is greater than the Three Pole
Shots target of 1 and the second fault was a multi-phase fault.
The total number of auto-reclosures is shown in the CB Control menu under Total
Reclosures. This value can be reset to zero with the Reset Total A/R command.
The selection of which protection is used to initiate auto-reclose can be made using the
settings Initiate AR, No Action or Block AR for the protection functions listed in the
auto-reclose menu. See section 4.1.7.2 ‘Auto-reclose Initiation’ for more details.
For multi
-phase faults the auto-reclose logic can be set to allow auto-reclose block for 2 and
3 phase faults or to block auto-reclose for 3 phase faults only using the setting Multi Phase
AR - Allow AR/BAR 2 & 3 Phase/BAR 3 Phase in the Auto-reclose settings.
Trip
(AR1 in Prog) or (AR3 in Prog)
AR Close
Force 3 Pole
Reclaim Time
Successful Close
P1024ENc
Figure 86 Auto-reclose timing diagram - single fault
Trip
(AR1 in Prog) or (AR3 in Prog)
AR Close
Force 3 Pole
Reclaim Time
Successful Close
P1025ENc
Figure 87 Auto-reclose timing diagram - repeated fault inception
To Next Page
Loading...
