5-19
Specifications and Reference Data
Implementation
The Intermittent Sensor Detect feature can be turned ON or OFF when
the transmitter is connected to a Model 275 HART Communicator.
Select 1 Device Setup, 4 Detailed Setup, 3 Output Conditioning,
5 Intermit Detect, 1 Intermit Detect. Choose “On” or “Off”. “On” is the
normal setting. The threshold value can be changed from the default
value of 2% by proceeding with the following steps: Select 1Device
Setup, 4 Detailed Setup, 3 Output Conditioning, 5 Intermit Detect,
2 Threshold Val.
Turning the Intermittent Sensor Detect feature OFF or leaving it ON
and increasing the threshold value above the default 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 5-6) up to the threshold value (100% of
output range if Intermittent Sensor Detect is OFF).
Figure 5-6. Open Sensor Reponse with
DampingOn(3Cases).
Unless rapid response rate is necessary, the suggested setting of
the Intermittent Sensor Detect mechanism is ON.
644-644_03A
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.
0.5 1.0 1.5 2.0 2.5 3.0 3.50
0
5
10
15
20
25
High Alarm
Transmitter Output (mA)
Time (seconds)
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