ABB C1300 User Manual page 36

C1300
Advanced circular chart recorder
34
Trip Level
Set the value at which the alarm is to activate.
For High and Low Process alarms, the value is set in engineering units.
For Fast and Slow Rate alarms, the trip level is set as a percentage of the engineering span
(engineering range high – engineering range low) per hour, between 500 and 500% in 0.1%
increments.
Hysteresis
Set the hysteresis value, either in engineering units (High and Low Process alarms) or as a
percentage of the engineering span (Fast and Slow Rate alarms).
Hysteresis is operational only when the alarm is active. The alarm is activated at the trip level but
is de-activated only after the alarm variable has moved into the safe region by an amount equal to
the hysteresis value. For rate alarms this setting is a percentage of the trip level.
Time Hysteresis
Set the time hysteresis value required, between 0 and 9999 seconds.
If a Time Hysteresis value is set, the alarm becomes active only when the alarm condition is
present continuously for the time set.
If a Hysteresis value is also set (see above) and an alarm is activated, the alarm remains active
until the process variable moves outside the hysteresis band. When the alarm condition no longer
exists the alarm becomes inactive immediately, i.e. time hysteresis does not affect turning off of
alarm states.
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3 Configuration
IM/C1300 Rev. J