Operation P54x/EN OP/La4
MiCOM P543, P544, P545 & P546
(OP) 5-185
OP
Following this introduction to the logic sequence, is a comprehensive description of the auto-
reclose and circuit breaker operation.
An auto-reclose cycle can be internally initiated by operation of a protection element,
provided the circuit breaker is closed until the instant of protection operation.
The operation of the auto-reclose sequence is controlled by the “Dead Timers”. The user
can, via settings, determine what conditions will be used to initiate the dead timers as
described in section 5.6.6.9. In general, however, and for the p
urposes of this description,
the dead timers can be considered to start upon initiation of the auto-reclose cycle by the
protection.
If only single phase auto-reclose AR 1P is enabled then the logic allows only a single shot
auto-reclose. For a single phase fault, the single phase dead timer SP AR Dead Time
starts, and the single phase auto-reclose in progress signal CB1 AR 1p InProg (DDB 845) is
asserted. For a multi-phase fault the logic triggers a three phase trip and goes to lockout.
If only three phase auto-reclose AR 3P is enabled then, for any fault, the three phase dead
timers: 3P AR DT Shot 1, 3P AR DT Shot 2, 3P AR DT Shot 3, 3P AR DT Shot 4, (Dead
Time 1, 2, 3, 4) are started and the three phase auto-reclose in progress signal
CB1 AR 3p InProg (DDB 844) is asserted. The logic forces a three phase trip by setting
AR Force CB1 3P (DDB 858) for any single phase fault if only three phase auto-reclose
AR 3P is enabled.
If single and three phase auto-reclose AR1/3P are enabled then, if the first fault is a single
phase fault the single phase dead time SP AR Dead Time is started and the single phase
auto-reclose in progress signal CB1 AR 1p InProg (DDB 845) is asserted. If the first fault is
a multi-phase fault the three phase dead timer 3P AR DT Shot 1 is started and the three
phase auto-reclose in progress signal CB1 AR 3p InProg (DDB 844) is asserted. If the relay
has been set to allow more than one reclose (AR Shots >1) then any subsequent faults will
be converted to three phase trips by setting the signal AR Force CB1 3P (DDB 858). The
three phase dead times 3P AR DT Shot 2, 3P AR DT Shot 3 and 3P AR DT Shot 4 (Dead
Times 2, 3, 4) will be started for the 2nd, 3rd and 4th trips (shots) respectively. The three
phase auto-reclose in progress signal CB1 AR 3p InProg (DDB 844) will be asserted. If a
single phase fault evolves to a multi-phase fault during the single phase dead time
(SP AR Dead Time) then single phase auto-reclose is stopped. The single phase
auto-reclose in progress signal CB1 AR 1p InProg (DDB 845) is reset, the three phase
auto-reclose in progress signal CB1 AR 3p InProg (DDB 844) is set, and the three phase
dead timer 3P AR DT Shot 1 is started.
At the end of the relevant dead time, provided system conditions are suitable, a circuit
breaker close signal is given. The system conditions to be met for closing are that the
system voltages are in synchronism or that the dead line/live bus or live line/dead bus
conditions exist, indicated by the internal system check synchronizing element, and that the
circuit breaker closing spring, or other energy source, is fully charged as indicated by the
CB Healthy input. The circuit bre
aker close signal is cut-off when the circuit breaker closes.
For single phase auto-reclose no voltage or synchronism check is required as synchronizing
power is flowing in the two healthy phases. For three phase auto-reclosing, for the first shot
only, auto-reclose can be performed without checking that the voltages are in synchronism
by means of a setting. This setting, CBxL SC Shot 1, can be set to Enabled to perform
synch-checks on shot 1 for CB1 or CB2, or Disabled to not perform the checks.
When the circuit breaker has closed, the Set CB1 Close (DDB 1565) signal from the
CB autoclose logic goes high and the reclaim time (“Reclaim Time”) starts. If the circuit
breaker has remained closed and not tripped again when the reclaim timer expires, the
auto-reclose cycle is complete, and signal CB1 Succ 1P AR (DDB1571) or CB1 Succ 3P
AR (DDB 852) is generated to indicate the successful reclosure. These signals also
increment the relevant circuit breaker successful auto-reclose shot counters
CB1 SUCC SPAR, CB1 SUCC 3PAR Shot1, CB1 SUCC 3PAR Shot2, CB1 SUCC 3PAR
Shot3 and CB1 SUCC 3PAR Shot4, as well as resetting the circuit breaker auto-reclose in
progress CB1 ARIP signal.
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