44x/EN AP/Hb6
-156 MiCOM P40 Agile
Figure 117: Autoreclose inhibit window
Figure 118: Autoreclose inhibit window logic
The inhibit time-delay is started at the end of dead time if CB healthy is absent
5.10.1.6 Check synchronism on 3-pole reclosure
The Check synchronism on 3-pole reclosure (‘C/S on 3P Rcl DT1’) setting is used to
“Enable/Disable” system checks for the first reclose after a 3 pole trip in an autoreclose
cycle. When the “SysChk on Shot 1” is set to “Disabled”, no system checks are required for
the first reclose which may be preferred when high speed autoreclose is applied to avoid the
extra time for a system check. Subsequent reclose attempts in a multi-shot cycle will still
require a system check.
5.10.1.7 Block autoreclose
When enabled (the relevant bit is set to 1), the detected fault will block the autoreclose, and
cause a lockout if autoreclose is in progress. If a single-pole is in progress, a three-pole trip
will be issued and the autorecloser will lock-out.
It can be set when protection operation is required without autoreclose. A typical example is
for a transformer feeder, where autoreclosing may be initiated by the feeder’s protection
relay but blocked by the transformer’s protection relay. Similarly, where a circuit breaker low
gas pressure or loss of vacuum alarm occurs during the dead time, autoreclosure should be
blocked – and ‘Block A/R’ can be used to perform this blocking logic.
Autoreclose logic is partly fixed, so that autoreclosure is always blocked for any Switch on to
Fault, Stub Bus Protection, Broken Conductor or Zone 4 trip. Autoreclosure is also blocked
when relay Supervision functions detect a Circuit Breaker Failure or Voltage
Transformer/Fuse Failure. All other protection trips initiate autoreclosure (when blocking bit
is set to 0).
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