GE D90 Plus Instruction Manual page 87

CHAPTER 4: FRONT PANEL INTERFACE
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
• 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
Sequence (initial Process (status)
state)
Normal Normal
Normal Abnormal
Alarm Normal
Alarm Normal
Alarm Abnormal
Acknowledged Abnormal
Acknowledged Normal
Ringback Normal
Ringback Abnormal
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).
Pushbutton Sequence (final
(input) state)
N/A N/A
N/A Alarm
N/A Alarm
Acknowledged Normal
Acknowledged Acknowledged
N/A Acknowledged
N/A Ringback
Reset Normal
N/A Acknowledged
ANNUNCIATOR
Visual indication
Off
Fast flash
Fast flash
Off
On
On
Slow flash
Off
On
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