Vaisala HMP228 User Manual
Page 36
HMP228
Operating Manual
M210282en-A
30
•
Check that the reading corresponds with the reading of the reference
instrument. If not, adjust the second point.
•
If necessary, adjust with the arrow switches to the correct value and
press ENT. At the second calibration point the second LED from the
left flashes.
4.6.3
Temperature channel adjustment with Pt 100 simulators
Switch the power off and disconnect the wires to the Pt 100 sensor from solder
lugs TP5, TP6 and TP7.
TP6
TP5
TP7
X88
Figure 4.6.3.1
Location of solder lugs TP5, TP6 and TP7 and
connector X88
Connect a Pt 100 simulator to connector X88 and set it at the lowest tempera-
ture to be calibrated.
X88
Pt 100
Figure 4.6.3.2
Connecting the Pt 100 simulator to connector X88
Switch the power on. Follow the one or two point calibration instructions in
Chapters 4.6.1 - 4.6.2.
Switch the power off. Disconnect the Pt 100 simulator and reconnect the Pt
100 wires to solder lugs TP5, TP6 and TP7.
The correct connections according to the wire colours are:
TP5
TP6
TP7
TP8
blue
green
yellow
black
If there is not a Pt 100 simulator available, the adjustment can be made with
two resistors of 84
Ω
and 154
Ω
whose resistance is known precisely. Measure
the resistor with a resistance meter. Look up the corresponding temperature
value from a Pt 100 conversion table or calculate it using the following
equation: