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TTI-22 Iss.04– 11/15
The calibration time Cal.Time is automatically set to 100 days. You can individually customize the
calibration time.
Caution:
The calibration time can only be estimated. Therefore it is your own responsibility to perform
regular checks of the measuring device at the triple point or freezing point of water.
After the adjustment, perform another calibration to check TTI-22 as follows:
11. Choose menu 1 Sel. Display & Start > 3 Resistance Stat.
12. Use the <
> key to set the amount of values N, with which the mean value is calculated, to 50.
13. Wait approx. 1.5 minutes.
14. Check if the displayed mean value of the standard resistor accords with the mean value stated in the
calibration certificate.
The two values shall at most differ by the measuring uncertainty of TTI-22.
Performing a manual adjustment
For a manual adjustment, as opposed to the automatic one, you need to calculate the new value of the
internal reference resistor and enter it into TTI-22 yourself.
The following formula is used for the calculation:
an
ext
old
f
new
f
R
R
x
R
R
Re
Re
(Equ. 3)
R
Ref[new]
calculated value of the internal reference resistor in
Ω
R
Ref[old]
value of the internal reference resistor stored in TTI-22 in
Ω
R
ext
value of the externally connected standard resistor in
Ω
according to calibration certificate
R
an
mean value of the external standard resistor displayed on TTI-22 (amount of the measuring
values used for averaging: N=50)
Equipment:
-
TTI-22
-
Standard resistor [100
Ω
or 400
Ω
]
-
Calibration certificate for the standard resistor certified by a bureau of standards [measuring
uncertainty < 1 ppm]
-
Thermostat
1.
Find the value for RRef[old] in the menu 2 Edit Configuration > 2 Reference Resistor > 1
Edit
Int. RRef.
2.
Find the value Rext in the calibration certificate of the standard resistor.
3.
To determine the value Ran, the standard resistor in the thermostat needs to be brought to the
reference temperature stated in the calibration certificate.
4.
Connect the standard resistor to sensor channel 1.
5.
Choose menu 1 Sel. Display & Start > 3 Resistance Stat.