ABB L150 User Manual page 26

...4 CONFIGURATION MODE
...4.3.2 Alarms – Figs. 4.3, 4.4, 4.5 and 4.6
PV
Alarm
On
PV
Alarm On
Note.
High/Low Latch Alarms
value rises above the high latch alarm trip point value or falls below the low
latch alarm trip point value. The latch alarm trip point values are configured
in engineering units in the Set Up Level (Level 2). The alarm remains active
until it is acknowledged and the alarm process condition is removed. The
alarm can be acknowledged using the keys on the instrument front panel
(see page 3) or via the volt-free digital input once it has been configured to
provide a remote alarm acknowledge facility.
24
High Latch Alarm
Alarm
Latched
Low Latch Alarm
– An alarm becomes active when the process variable
Fig. 4.6 Latch Alarms
Alarm
Latched
Alarm
Acknowledgement
State
Alarm Trip
Value
Alarm Trip
+ Hysteresis
Alarm Off
Alarm
Acknowledgement
State
Alarm Trip
+ Hysteresis
Alarm Trip
Value
Alarm
Off