Vaisala HMP230 - Manual (Page 74)

HMP230 SERIES
User's Guide
M210225en-B
68
Set the Pt 100 simulator at the highest temperature to be calibrated and press
any key. Enter the second point (gain) reference reading. If second reference is
not needed, press <cr> to complete one point offset correction.
8.4.2. Adjustment using display commands
Select Cali in the main menu and then T cal; select two-point calibration T 2
point cal. Change the first point reading with the arrow keys and press ENT.
Set the Pt 100 simulator at the highest temperature to be calibrated and adjust
the second point (gain) to the reference reading. If there is no second refer-
ence, press ENT to complete one point offset correction.
8.4.3. Adjustment using LED commands
Connect an ammeter/voltmeter to the analogue outputs (connector X2). Give
command ¡¡l¡ and adjust the first point (offset) with the arrow switches to
the same reading with the reference and press ENT switch.
Set the Pt 100 simulator at the highest temperature to be calibrated and adjust
the second point (gain) to the reference reading. If there is no second refer-
ence, press ENT to complete one point offset correction.
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 for different
transmitters are:
TP5 TP6 TP7 TP8
HMP231 green green brown brown
HMP233(120
°
C)/234/
235/238
blue green yellow black
HMP233 (80
°
C) blue white or green yellow red or 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:
T = D0 +R x {D1 + R x [D2 + R x (D3 + R x D4)]}
where
D0 = -243.5673014
D1 = 2.278542701
D2 = 0.002050681
D3 = -6.15025E-06
D4 = 1.34949E-08