TESTO 6681 Profibus Instruction Manual page 63

1 Open transmitter (see chapter 1.3.3, page 25).
2 Connect measuring cable to the terminals of the third analog output and
guide through the cable coupling and out of the transmitter.
3 Reassemble upper part of transmitter.
4 Connect cable ends to the inputs of the multimeter.
5 Transfer the reference analog value measured with the multimeter to the
P2A software (see volume 2, chapter 3, page 135) or enter it via the user
menu (see chapter 1.4.6.9, page 81).
6 Remove the upper part of the transmitter, detach the cable connections
for the adjustment of the 3rd analog output and reassemble the
transmitter.
1.3.6.5 High-humidity adjustment for testo 6614
Mollier diagram
"Microclimate"
sensor conditions
After heating
With the testo 6614, the rear of the Testo humidity sensor is heated, creating
a microclimate around the sensor (within the filter) that is constantly 5 K
warmer than the actual process conditions. As can be seen in the Mollier
diagram, this reduces the relative humidity at the sensor from around
100 % RH to a lower value, e.g. 73 % RH. In this range, the reaction time of
the sensor is noticeably shorter than in the condensation range and the risk
of the sensor corroding is also reduced. Using the separate temperature
probe, the testo 6681 transmitter compensates the microclimate conditions
and displays the process readings.
testo 6681 Profibus
e.g. 73 % RH
100 % RH
High-humidity process
conditions
Mist
- 1.3 Commissioning 63