GE D90 Plus - Page 87

CHAPTER 4: FRONT PANEL INTERFACE ANNUNCIATOR
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 77
• The Next Alarm button navigates horizontally through the current alarms that are
active, from left-to-right, starting with the first row of alarms. A border is drawn
around the current alarm.
• The Ack/Reset button is used to acknowledge alarms or reset latched and
acknowledgeable alarms that are in the ringback state.
The annunciator alarm sequence conforms to ISA 18.1-1979 (R1992) standard, type R.
Figure 57: Annunciator alarm sequence
The table outlines annunciator states.
Table 5: Acknowledgeable alarm states
The visual indications display as follows:
• Off — Grey text on a darker grey background
• On — User-configurable
• Fast flash — Alternating between off and on state two times per second
• Slow flash — Alternating between off and on state one time per second
In the event of an alarm, the page containing the alarm is promoted to active page. If there
are multiple pages with alarms, the page with the lowest page number is promoted.
If there are alarms on multiple pages, and alarms on some pages have already been
acknowledged (but not cleared) by the user, then the pages with active alarms move ahead
of the pages that have acknowledged alarms. The user always has to navigate through the
pages of alarms to view them.
Display of alarm pages is prioritized according to active window (unacknowledged or
flashing alarm) and page number (for example, if two pages have an unacknowledged
alarm, the page with the lowest number is promoted automatically as the displayed page).
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Sequence (initial
state)
Process (status) Pushbutton
(input)
Sequence (final
state)
Visual indication
Normal Normal N/A N/A Off
Normal Abnormal N/A Alarm Fast flash
Alarm Normal N/A Alarm Fast flash
Alarm Normal Acknowledged Normal Off
Alarm Abnormal Acknowledged Acknowledged On
Acknowledged Abnormal N/A Acknowledged On
Acknowledged Normal N/A Ringback Slow flash
Ringback Normal Reset Normal Off
Ringback Abnormal N/A Acknowledged On