EN
40
WIKA operating instructions, model CTR3000
14191761.01 05/2019 EN/DE
6. Commissioning, operation
■
T
min
Probes may have a minimum temperature set for them (positive or negative). When the probe is assigned to a channel, the
probe temperature is checked against the set minimum and a range error (exclamation mark left beside the button
13
)
issued if the minimum temperature is exceed.
■
T
max
Probes may have a maximum temperature set for them (positive or negative). When the probe is measured and active on
a channel, the probe temperature is checked against the set maximum and a range error (exclamation mark left beside the
button
13
) issued if the maximum temperature is exceed.
■
Last cal date
Please enter the last calibration date of the thermometer.
If the system date = last cal date + 1 year then a pop up is coming up which reminds that the probe is due to recalibration.
The recalibration cycle depends mainly on the thermal stress on the thermometer. The calibration time can only
be estimated and is decided on by the user. Therefore check the calibration system at the triple point or freezing
point of water on a regular basis (independent of the recalibration cycle). Recommendation is a calibration once a
year.
■
Conversion
a.
None, only the resistance is displayed
b.
Steinhart-Hart like specified in the calibration certificate: a, b, and c
The Steinhart-Hart equation is commonly used to convert the measured resistance to temperature.
1/T = a + b∙ln(R) + c ∙ ln³ (R)
c.
Polynomial like specified in the calibration certificate; c0, c1, c2 and c3
1/T= c
0
+ c
1
∙ ln (R)+ c
2
∙ ln² (R) + c
3
∙ ln³ (R)
Make sure using the correct calibration parameters for the thermometer, since incorrect calibration parameters
lead to erroneous results. The coefficients can be found in the calibration certificate while ordered a calculation.
6.4.3.4 Configure existing probes
Under the menu chapter
“Configure existing probe”
existing standard or user-defined probes can be changed or updated
e.g. with new calibration data.
As soon as you click on a probe on the left side, all parameters depending on the probe type (resistance thermometer,
thermocouple or thermistor) will open on the right side.
For the standard probes 3W-PT100, 4W-PT100, 4W-PT25, Thermistor and TC (K) only a few changes can be done. All other
user-defined probes can be configured as needed.
