model 2704 controller installation and operation handbook - Soliton

Alarm Operation
2704 Controller
7.2.6. Rate Of Change Alarm (Negative Direction)
The Process Value falls faster than the alarm setting.
↑
PV
Alarm On
Alarm Off
Negative
Rate of
Change set
to x units per
Actual rate of
change > x
units per min
↓
↑
Hysteresis
Time
→
7.2.7. Rate Of Change Alarm (Positive Direction)
The Process Value rises faster than the alarm setting.
↑
PV
Alarm On
Alarm Off
Actual rate of
change > x
units per min
↓
Hysteresis
↑
Positive Rate
of Change
set to x units
per min
Time
→
Notes:
1. Separate alarms are required for positive and negative rates of change
2. An alarm is indicated during the period that the actual rate of change is greater than the
set rate of change.
3. There may be a small delay before the instrument displays an alarm condition since the
instrument requires several samples. This delay increases if the set value and actual value
are close together
4. A hysteresis value of, say, 1 unit per second will prevent the alarm from ‘chattering’ if
the rate of change varies by this amount
7-6 Installation and Operation Handbook. Part No HA026502 Issue 1.0 Apr-00