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TTI-22 Iss.04– 11/15
6.
Use the <
> key to set the amount N, with which the mean value is calculated, to 50.
7.
After approx. 1.5 minutes, read the mean value Ran from the display.
8.
Insert the determined values in the formula and in this way calculate the new value of the internal
reference resistor RRef[new].
9.
Save the new value of the reference resistor in TTI-22 via the menu 2 Edit Configuration >2
Reference Resistor > 1 Edit Int. RRef.
10. Now check if the displayed mean value of the external standard resistor accords with the mean value
stated in the calibration certificate.
11. Note the date, measuring medium and RRef[new] in a measuring protocol and file it with care.
Example:
R
Ref[old]
(stored in TTI-22)
= 400.003
Ω
R
ext
(value of the externally connected standard resistor
according to calibration certificate)
= 100.014
Ω
R
an
(displayed value on TTI-22)
= 100.0185
Ω
As this shows, the displayed value deviates from the actual value stated in the calibration certificate.
Insertion in Equ. 3 gives:
9850
.
399
0185
.
100
014
.
100
003
.
400
Re
x
R
new
f
After the new value 99.9985
Ω
has been entered for RRef, the mean value displayed on TTI- 22 has to
match the actual value of the standard resistor.
Otherwise repeat the procedure.
E.2
Calibrating and Adjusting the Sensor
You can calibrate and adjust sensors by connecting a known, certified reference sensor and your un-adjusted
sensor to a TTI-22 unit and in this way determining the value of the sensor resistance using a highly precise
thermostat at various temperatures. With equations of DIN IEC 751 or ITS-90 you can calculate the sensor
parameters.
Equipment:
-
TTI-22 (adjusted)
-
Reference sensor with calibration certificate
-
Un-adjusted sensor
-
Thermostat
1.
Connect the reference sensor to sensor channel 1.
2.
Connect the un-adjusted sensor to sensor channel 2.
3.
Select the display type Resistance Stat.
4.
Read the values for the resistance.
5.
Calculate the coefficients with the according formula.
6.
Record the calibration and adjustment data in writing and file these records with care.
7.
Enter the newly calculated coefficients for your sensor into TTI-22 and assign these
calibration parameters to a sensor input.
