P54x/EN OP/La4 Operation
(OP) 5-164
MiCOM P543, P544, P545 & P546
OP
Where the check synchronism function is set, this can be enabled to supervise manual
circuit breaker close commands. A circuit breaker close output will only be issued if the
check synchronism criteria are satisfied. A user settable time delay is included (‘C/S
Window’) for manual closure with check synchronizing. If the checksynch criteria are not
satisfied in this time period following a close command the relay will lockout and alarm.
In addition to a synchronism check before manual reclosure there is also a CB Healthy
check if required. This facility accepts an input to one of the relays opto-isolators to indicate
that the breaker is capable of closing (circuit breaker energy for example). A user settable
time delay is included (‘Healthy Window’) for manual closure with this check. If the CB does
not indicate a healthy condition in this time period following a close command then the relay
will lockout and alarm.
Where auto-reclose is used it may be desirable to block its operation when performing a
manual close. In general, the majority of faults following a manual closure will be permanent
faults and it will be undesirable to auto-reclose.
The ‘AR Inhibit Time’ setting can be used to prevent auto-reclose being initiated when the
CB is manually closed onto a fault. Auto-reclose is disabled for the AR Inhibit Time following
manual CB closure.
If the CB fails to respond to the control command (indicated by no change in the state of CB
Status inputs) a ‘CB Failed to Trip’ or ‘CB Failed to Close’ alarm will be generated after the
relevant trip or close pulses have expired. These alarms can be viewed on the relay LCD
display, remotely via the relay communications, or can be assigned to operate output
contacts for annunciation using the relays programmable scheme logic (PSL).
Note that the ‘Healthy Window’ timer and ‘C/S Window’ timer set under this menu section are
applicable to manual circuit breaker operations only. These settings are duplicated in the
Auto-reclose menu for Auto-reclose applications.
The ‘Lockout Reset’ and ‘Reset Lockout by’ setting cells in the menu are applicable to CB
Lockouts associated with manual circuit breaker closure, CB Condition monitoring
(Number of circuit breaker operations, for example) and auto-reclose lockouts.
The CB Control Logic is illustrated in Figure 106.
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