Alarm And Saturation - Emerson Rosemount 3144P Reference Manual

Reference Manual
00809-0100-4021, Rev AA
March 2002
Figure 3-4. Change in Input
versus Change in Output with
Damping Enabled.
When damping is enabled, the transmitter will output a value at time (t)
according to the following equation:
Output
D = input step change at time t = 0
At the value to which the damping time constant is set, the transmitter output
is at 63 percent of the input change; it continues to approach the input
according to the damping equation above.
For example, as illustrated in Figure 3-4, if the temperature undergoes a step
change—from 100 degrees to 110 degrees, and the damping is set to 5.0
seconds, at 5.0 seconds, the transmitter outputs 106.3 degrees, or 63 percent
of the input change, and the output continues to approach the input curve
according to the equation above..
110.0
109.0
108.0
107.0
106.0
105.0
104.0
103.0
102.0
101.0
100.0
0.0 0.5 1.0 1.5 2.0

Alarm and Saturation

HART Fast Keys 1, 3, 4, 2
The Alarm/Saturation command allows the user to view the alarm settings (Hi
or Low). With this command it is also possible to change the alarm and
saturation values. To change the alarm values and saturation values, select
the value to be changed, either 1 Low Alarm, 2 High Alarm, 3 Low Sat., 4 High
Sat, or 5 Preset Alarms. Enter the desired new value. It must fall within the
guidelines given below.
• The low alarm value must be between 3.50 and 3.75 mA
• The high alarm value must be between 21.0 and 23.0 mA
The low saturation level must be between the low alarm value plus 0.1 mA
and 3.9 mA.
Example: The low alarm value has been set to 3.7 mA. Therefore, the low
saturation level, S, must be as follows:
3.8 ≤ S ≤ 3.9 mA.
(–t/damping)
= Input – De
(t) (ts)
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0
Time (Seconds)
Model 3144P
Input Value
Output Value
7.5 8.0 8.5 9.0 9.5 10.0
3-18