Super Systems 3L Series - Manual (Page 34)

Operations Manual Series 3L
34
9.2 Behavior of Alarms After a Power
Cycle
The response of an alarm after a power cycle depends
upon the latching type, whether it has been configured
to be a blocking alarm, it's state and the acknowledge
status of the alarm.
The response of active alarms after a power cycle is as
follows:
For a non-latching alarm or an event alarm blocking will
be re-instated, if configured. If blocking is not
configured the active alarm will remain active. If the
alarm condition has gone safe during the down time the
alarm will return inactive.
For an auto-latching alarm blocking will be re-instated, if
configured, only if the alarm had been acknowledged
prior to the power cycle. If blocking is not configured or
the alarm had not been acknowledged the active alarm
will remain active. If the alarm condition has gone safe
during the downtime the alarm will return inactive if it
had been acknowledged prior to the power cycle else it
will return safe but not acknowledged. If the alarm was
safe but not acknowledged prior to the power cycle the
alarm will return safe but not acknowledged.
For a manual-latching alarm blocking will not be re-
instated and the active alarm will remain active. If the
alarm condition has gone safe during the downtime the
alarm will return safe but not acknowledged. If the
alarm was safe but not acknowledged prior to the power
cycle the alarm will return safe but not acknowledged.
The following examples show graphically the behaviour
under different conditions:-
9.2.1 Example 1
Alarm configured as Absolute Low; Blocking: No
Latching
9.2.2 Example 2
Alarm configured as Absolute Low; Blocking: Manual
Latching
9.2.3 Example 3
Alarm configured as Absolute Low; Blocking: Auto
Latching
P
V
Alarm
SP
Power
on
Powe
r
off/on
Powe
r
off/on
Alarm
ON
Alarm
OFF
PV
Alarm
SP
Power
on
Power
off/on
Power
off/on
Alarm
ON
Alarm
OFF
Ack Ack Ack Ack
Note: The alarm will only cancel when the alarm
condition is no longer current AND then it is
acknowledged
PV
Alarm
SP
Power
on
Power
off/on
Power
off/on
Alarm
ON
Alarm
OFF
Ack
1
Ack 2 Ack
3
Ack 4
Ack 2 - alarm
output remains
in alarm
condition but
ALM indication
goes steady
Ack 3 - alarm output
remains active until the
condition causing the
alarm disappears
Ack 4 - alarm output
remains active until
acknowledged
Alarm
ON
Alarm
OFF