ABB DATUM L160 User Manual page 25

...4.3.2 Alarms – Figs. 4.3, 4.4, 4.5 and 4.6
100
50
Information
Fast/Slow Rate Alarms –
change in the process variable is faster or slower than the configured
alarm value. Rate of change alarm values are configured as a % of span
change per hour. The elapsed time period before the alarm condition is
detected is dependant upon the configured alarm value. This period can
be calculated as follows:
t =
t =
The alarm remains active until the rate of change in the process variable
returns to the non-alarm condition. The calculated time period (t)
elapses between the process variable reaching the non-alarm condition
and the alarm becoming inactive.
1 2
Alarm On
Alarm Off
an alarm becomes active when the rate of
10.81 +
trip value (as a % of eng. span/hr)
191 seconds
Fig. 4.5 Rate Alarms
4 CONFIGURATION MODE...
3
t (191 secs)
1800
Hours
4 5
t (191 secs)
23