22
Trip
Point
Alarm On
Alarm Off
Alarm
On
Alarm
Off
High Process
Low Process
Hysteresis
Hysteresis
Process
Variable
Fig. 4.4 Process Alarms
Information
Process Alarms – an alarm becomes active when the process variable rises
above the high process alarm trip point value or falls below the low
process alarm trip point value. Process alarm trip point values are
configured in engineering units in Set Up Level (Level 2). If an alarm
hysteresis value of zero is configured the alarm becomes inactive when
the process variable value returns past the alarm trip point value. If a
positive or negative hysteresis value is configured the alarm becomes
inactive when the process variable reaches the hysteresis point. The
hysteresis value is configured in engineering units e.g. if a hysteresis point
five inches H
2
0 below the alarm trip point is required, a hysteresis value of
–5.0 is configured. The programmable alarm hysteresis function can also
be utilized for pump control applications when an output relay is assigned
to an alarm.
…4.3.2 Alarms – Figs. 4.3, 4.4, 4.5 and 4.6
…4 CONFIGURATION MODE
To Next Page
Loading...
