Operation P54x/EN OP/La4
MiCOM P543, P544, P545 & P546
(OP) 5-195
OP
If the menu setting BF if LFail Cls is set to Disabled, the follower circuit breaker will reclose
even if the leader circuit breaker fails to reclose (for example, due to the absence of a CB
Healthy signal). When BF if LFail Cls is set to Disabled, an additional menu setting
Dynamic F/L becomes visible to further control the operation of the follower circuit breaker.
If the setting Dynamic F/L is set to Enabled, the follower circuit breaker will reclose with no
deliberate additional delay, i.e. at approximately the same instant that the leader circuit
breaker would have closed if it had been healthy. If the menu setting Dynamic F/L is set to
Disabled, the follower circuit breaker will reclose after an additional delay equal to the set
Follower Time.
If the menu setting BF if LFail Cls is set to Enabled then, if the leader circuit breaker fails to
reclose, the follower circuit breaker cycle is cancelled and auto-reclosing of both circuit
breakers is locked out.
The follower circuit breaker must be open for the follower delay time to start. For a single
phase follower auto-reclose cycle, the follower circuit breaker has to be open single phase.
For a three phase follower auto-reclose cycle, the follower circuit breaker has to be open
three phase.
When the follower delay time has timed out, the relevant internal signal CBxSPFTCOMP or
CBx3PFTCOMP (x = 1 or 2) is applied to the CB AutoClose logic, described later in section
5.6.6.11 to indicate that the follower time is
complete.
5.6.6.11 CB1 and CB2 auto close (P
544/P546)
The CB1 and CB2 auto close logic is shown in AR Figure 32 and Figure 33 (logic diagram
sup
plement).
When the end of a dead time or the end of a follower time is indicated by one of the following
internal signals, the auto close logic is executed :-
CB1 SPDTCOMP
CB1 3PDTCOMP
CB2 SPDTCOMP
CB2 3PDTCOMP
CB1 SPFTCOMP
CB1 3PFTCOMP
CB2 SPFTCOMP
CB2 3PFTCOMP
The auto close logic checks that all necessary conditions are satisfied before issuing a
AutoClose CB1 or AutoClose CB2 signal to the CB1 and CB2 overall control scheme as
shown in the AR Figure 43 and Figure 44 (logic diagram supplement) described in
se
ction 5.5.
For
any reclosure, the circuit breaker must be healthy (mechanism OK to close, and retrip if
necessary) and it should not be in a lockout state.
For any single phase reclosure, the circuit breaker must be open on one phase. For any
three phase reclosure, the circuit breaker must be open on all three phases and the
appropriate system check conditions (live bus/dead line, synch check etc) must be satisfied.
The system check conditions for CB1 leader reclose, CB2 leader reclose, CB1 follower
reclose and CB2 follower reclose are independently selectable by menu settings and are
described in section 5.6.6.15.
The auto
close signals (AutoClose CB1, AutoClose CB2) sent to the circuit breaker control
scheme are pulses lasting 100 milliseconds. Another pair of signals Set CB1 Close & Set
CB2 Close, DDBs (1565/1449) are set in conjunction with the auto close signals, but these
remain set until either the end of the auto-reclose cycle, or the next protection operation.
These signals are used to initiate the Reclaim timing logic and the CB AR Shots Counters
logic, described in sections 5.6.6.12 to 5.6.6.14.
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