AW T4 20 |
U N I V ER S A L 4 - W I R E , D UA L- I N P U T T R A N SM I T T ER | O I/AW T4 2 0 - EN R E V. B
43
Process Alarm
Used to configure up to 8 independent process alarms.
Menu
Comment
Default
Alarm 1 (to 8)
Source
Select the sensor signal for the process alarm source.
Type
Select the alarm type:
• High Process/Low Process/High Latch/Low Latch
Tag
Enter an alphanumeric alarm identification tag (16 characters maximum).
The tag is displayed as a diagnostic message and appears in the
Diagnostic Status Bar
and on the
Diagnostic View
page at
Operator
level – see page 27.
Trip
Set a trip value in engineering units.
Hysteresis
Set a hysteresis trip value in engineering units. The alarm is activated at the alarm trip level but
deactivated only when the process variable has moved into the safe region by an amount equal
to the hysteresis value – see Process alarm examples (Figure 32 and Figure 33) below.
Time Hysteresis
Set a time hysteresis trip value between 0.0000 and 9999.0 seconds.
If the alarm trip value is exceeded, the alarm is not activated until the
Time Hysteresis
value has expired.
If the signal goes out of the alarm condition before the
Time Hysteresis
has expired, the hysteresis timer
is reset.
Process alarm examples
Figure 32 High and low process alarm action
Figure 33 High and low latch alarm action
Processs Alarm
Exit
Menu
Select
Trip point
Trip point
PV
On
On
Off
Off
Hysteresis
Hysteresis
High process alarm
Low process alarm
Alarm
state
Alarm
state
Acknowledged
after condition
cleared
Acknowledged
before condition
cleared
Acknowledged
before condition
cleared
Acknowledged
after condition
cleared
Trip point
Trip point
PV
On
On
On
Off
Off
Off
Hysteresis
Hysteresis
High latch alarm
Low latch alarm
Alarm
state
Alarm
state
Alarm
state
Active
Active
Active
Active
Latched
Latched
Acknowledged
Acknowledged
On
Off
Alarm
state
