Siren with acknowledge
The horn output is activated when one or more alarms are active.
The horn output is deactivated when there are no active alarms. The horn output is also deactivated when all alarms are
acknowledged, even if there are still active alarms.
The horn output is affected when a new alarm is activated. To alert the operator to the new alarm, the horn output is deactivated for
the time in the Minimum down time parameter, and then activated again. If the horn output is connected to a siren, this gives a
wailing effect every time there is a new alarm.
There is no new Minimum down time when all the alarms are acknowledged.
Each time the horn output is activated, the horn output must remain activated for the time in the Minimum up time parameter, to stop
multiple new alarms from deactivating the horn output. The horn output will also be activated for the time in the Minimum up time
parameter even if all alarms are acknowledged.
Table 4.15
Siren with acknowledge parameters
Parameter Default Notes
Reset when new alarm Enabled
Minimum down time 0 s to 1 h Required
Minimum up time 0 s to 1 h Required
De-energise when all alarms are
acknowledged
Enabled
When all active alarms are acknowledged, the horn output is deactivated.
If there are no latched alarms, the horn output is also deactivated when all the
alarms do not exceed their set points, regardless of the acknowledgement
status of the alarms.
Siren with acknowledge example
Min. up time
Acknowledge
Alarm 1
Acknowledge
Alarm 2 and
Alarm 3
Min. up time
Min.
down time
Min. up time
Alarm 1
Alarm 2
Alarm 3
(1)
(3)
(2)
Horn
(4)
1 2 3 4 5
1. The horn output is deactivated when alarm 1 is acknowledged. There is no Minimum down time when the alarms are
acknowledged.
2. Alarm 2 becomes active, and shortly after that, alarm 3 become active. For alarm 2, the horn output remains activated
for the Minimum up time.
3. The horn output is then deactivated for the Minimum down time for alarm 3.
DESIGNER'S HANDBOOK 4189340911K UK Page 115 of 521
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