User Manual

SGD-SB2025NT-TUM, Part 2
Jan 12 Page 88 ALARMS
Figure 76. Examples of Alarm Indications.
12.4.2 Alarm Acknowledge
As an alarm indication will continue to be displayed even if the original event is no longer active,
the alarm may be acknowledged so that the external alarm output, ‘Isolated Output #2’ on the
Central NI, is deactivated. This also serves as a means of recognising if a subsequent alarm
condition occurs before the first has been cleared.
When an alarm is acknowledged, the alarm indication will change to a flashing Yellow border if no
other alarms are present on the unit. Once an alarm is acknowledged, the flashing Yellow
indication will cease immediately if the original alarm event is no longer active or will continue until
that alarm event becomes inactive. Individual status indicators will also adopt the flashing Yellow
state for the alarm acknowledged condition. In Figure 76 , Station NI#3 has an acknowledged
alarm and the following figures will show the process of other alarms being acknowledged.
Alarms are acknowledged through the ‘Engineering’ facility for the unit concerned using the ‘Ack
Alarms’ button, which will only become active if an alarm is present on the page in view. If alarms
exist on more than one page, then each page must be acknowledged individually. Only when all
alarms have been acknowledged will the common alarm indication for the unit enter the
acknowledged state.
If alarms are originating from different units, each unit will have to be acknowledged individually. If
multiple alarms are present on a channel, only when all alarms on the channel have been
acknowledged will the external alarm output cease.
The alarm example in Figure 77 overleaf shows that the TM alarm is due to the ‘PPS’ Status
indicator on the ‘Misc Alarms’ page. The ‘Ack Alarms’ button is enabled and when it is selected,
the alarm indication changes to the acknowledged state and the ‘Ack Alarms’ button becomes
disabled. If a second alarm had been present on the same page, that too would have been
acknowledged.