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Goals and Symptoms
Onboard Alarms from Micrologic Trip Units in PowerLogic SCADA (PLS) are represented by Time-Stamped Digital Alarms.
When a Time-Stamped Digital Alarm (Onboard Alarm) becomes active, an entry is placed in the Event Log with the State of "Appearance". Then exactly 1 second later, another entry is placed in the Event Log with the same Description, but with the State of "Disappearance". This can be confusing, however, because the situation/condition that caused the alarm to become active has not actually disappeared as the Event Log shows. It may still be in the active state (e.g. breaker is still open, it has not yet closed).
When the Onboard Alarm is no longer in the active state (e.g. breaker has been closed), two additional entries are placed in the Event Log. Again, the first entry has a State of "Appearance" and the second entry, appearing exactly 1 second later, has a State of "Disappearance".
Other types of alarms, such as Digital Alarms or Advanced Alarms, will populate in the Event and Alarm Logs with an entry that has the State of "Appearance" when the alarm becomes active. It will remain in this "Appearance" state until the alarm in no longer active or returns to the normal operating state, at which point, there will be a new entry in the Event and Alarm Logs with the State of "Disappearance" indicating that the alarm is no longer active.
Why do the Onboard Alarms from the Micrologic Trip Units show an entry for the State of "Appearance" and then another entry for the State of "Disappearance" even though the Onboard Alarm is still active?
Facts and Changes
These "Onboard Alarms", such as Breaker Opened, Breaker Closer, etc., come from the Breaker Manager. These "alarms" are Events in the breaker. The breaker creates this "alarm" as more of a time-stamped Event for "the breaker opened", it is NOT an alarm for "the breaker IS open". There is not a pickup/dropout state to this, so the driver will just show this as appearance and then disappearance with a 1 second time lapse. When the "Onboard Alarm" comes in, it must be shown as active (appearance), and because it is an event (one-shot), it must also be de-activated (disappearance). This is so that when the next "Onboard Alarm"/Event comes in, the software can display it as active again with the new time-stamp.
Below is a list of alarms from the Breaker Manager that are "alarms" but act as "events":
1 RESET or system energised
2 Configuration data stored in the chassis manager
3 Spring charged
4 Circuit breaker opened (O)
5 Circuit breaker closed (F)
6 Circuit breaker tripped (SD)
7 Circuit breaker fault tripped (SDE)
10 Closing command input remotely (AUTO) (XF)
11 Opening command input remotely (AUTO) (MX)
12 Modification of Modbus address
13 Event log reset
14 Clock update input locally accepted
15 Clock update input locally rejected (synchronization by the supervisor)
Causes and Fixes
If an alarm is needed to represent "breaker is currently open" or "breaker is currently closed", then the user should create an alarm using the position tag, "XCBR1\Pos".