Process Alarms - Brainchild L91 User Manual

3-6 Process Alarms

The output 2 will perform process alarm function by selecting
ALM for OUT2 and PV.H.A or PV.L.A for AL.FN. If PV.H.A is
selected the alarm will perform process high alarm. If PV.L.A
is selected the alarm will perform process low alarm. The
process alarm sets an absolute trigger level. When the
process exceeds that absolute trigger level an alarm occurs.
The trigger level is determined by SP2 (Set point 2 value)
and AL.HY (Alarm hysteresis value). The hysteresis value is
introduced to avoid interference action of alarm in a noisy
environment. Normally AL.HY can be set with a minimum
value(0.1).
Trigger levels for process high alarm are SP2 and SP2
AL.HY.
Trigger level for process low alarm are SP2+AL.HY and Sp2.
There are two types of alarm mode can be selected, these
are: normal alarm and latching alarm.
Normal Alarm: AL.MD= NORM
When a normal alarm is selected, the alarm output is de-energized in
the non-alarm condition and energized in an alarm condition.
Latching Alarm: AL.MD= LTCH
If a latching alarm is selected, once the alarm output is
energized, it will remain unchanged even if the alarm
condition has been cleared unless the power is shut off or
the RESET key (or remote reset button) is pressed.
Failure Transfer: AL.FT = OFF or ON
In case of Sensor Break
output will be on or off according to the selection of AL.FT.
Examples:
SP2 = 200
AL.MD = NORM
36
or A-D Failure
AL.HY = 10.0
AL.FN = PV.H.A
UM0L911C
occurs, the alarm