www.miinet.com
Moore Industries-International, Inc.
- 12 -
User’s Manual
224-790-00K
May 2018
Rate-of-Change
and
Stuck Input Alarms
- are used to detect changes or lack of changes in the
measured value in units per second.
A
Rate-of-Change Alarm
monitors an input for a change in value with respect to time (see Figure
1.3). The alarm is set to trip when the input rate-of-change exceeds a user-selected amount (Delta)
over a user-selected time period (Delta Time). This can be set to detect:
- positive rate of change to alarm if the input is rising too fast
- negative rate of change to alarm if the input is falling too fast
- absolute rate of change to alarm if the input rises or falls too fast
A
Stuck Input Alarm
also monitors an input for a change in value with respect to time (see Figure
1.4). The alarm is set to trip when the input does
not
change by a user-selected amount (Delta) over
a user-selected time period (Delta Time). To set the correct value for delta and delta time, you need
to understand the expected process variations to avoid false trips and the input signal noise and
averaging filter settings to prevent missing stuck inputs.
Note:
The Stuck Input Alarm is not available in firmware 3.3 or earlier.
Figure 1.3.
Rate-of-Change Alarm Trip.
Figure 1.4.
Stuck Input Alarm Trip.
> limit
Trip Point
T
t
t
Change in Input Signal
Change over Time
> limit
Trip Point
T
t
t
Change in Input Signal
Change over Time
Programmable Limit Alarm Trips
SPA
2
SECTION 1
