Super Systems 3 Series - Manual (Page 65)

Series 3 Operations Manual
65
12.2 Behaviour 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, its 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:
12.2.1 Example 1
Alarm configured as Absolute Low; Blocking: No Latching
12.2.2 Example 2
Alarm configured as Absolute Low; Blocking: Manual
Latching
12.2.3 Example 3
Alarm configured as Absolute Low; Blocking: Auto Latching
PV
Alarm
SP
Power
on
Power
off/on
Power
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is no longer current AND then it is acknowledged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