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...4.3.2 Alarms – Figs. 4.3, 4.4, 4.5 and 4.6
100
50
Note.
Fast/Slow Rate Alarms
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 = 10.81 +
t = 191 seconds
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 change in
trip value (as a % of eng. span/hr)
Fig. 4.5 Rate Alarms
4 CONFIGURATION MODE...
3
4
t (191 secs)
1800
Hours
5
t (191 secs)
23
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