Rosemount FISHER-ROSEMOUNT 244EH, Руководство по эксплуатации продукта

Страница: 33 / 60

3-9
Transmitter Behavior with Intermittent Sensor Detect ON
When the Intermittent Sensor Detect feature is switched ON , the
transmitter can eliminate the output pulse caused by intermittent open
sensor conditions. Process temperature changes (
∆
T) within 2% of the
output range will be tracked normally by the transmitter’s output. A
∆
T
greater than 2% of the output range will activate the intermittent
sensor algorithm. True open sensor conditions will cause the
transmitter to go into alarm.
Transmitter Behavior with Intermittent Sensor Detect OFF
When the Intermittent Sensor Detect feature is switched
OFF
, the
transmitter tracks all process temperature changes, even if they are the
consequence of an intermittent sensor. The output delay due to the
intermittent sensor algorithm will be eliminated.
Implementation
The Intermittent Sensor Detect feature can be turned
ON
or
OFF
using
a Model 244E transmitter with software version 5.4.1 or earlier with
the Model 244EC software configuration tool when the transmitter is
connected to the Model 244EC Configurator.
Turning the Intermittent Sensor Detect feature
OFF
does not affect the
time needed for the transmitter to output the correct alarm signal after
detecting a true open sensor condition. However, the transmitter may
briefly output a false temperature reading for less than 0.5 seconds in
either direction (see Figure 3-4) up to100% of output range.
Figure 3-4. Open Sensor Response
(Three Cases)
Unless rapid response rate is necessary, the suggested setting of the
Intermittent Sensor Detect mechanism is
ON .
0
0
5
10
15
20
25
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
T
ransmi
tt
er
Outpu
t
(m
A
)
Time (seconds)
A false temperature output in
either direction up to the
threshold value (100 % of output
range if Intermittent Sensor Detect
is OFF) is possible when an open
sensor condition is detected.
Normal open sensor responses
High Alarm
644-644_03