WIKA CTD9300 - Handbuch (Seite 33)

9037926 03/2005
Temperature Dry Well Calibrators CTD 9300
3. Moduses and Functions
GB
33 WIKA Operating Instructions CTD 9300 Rev. 1
Fig. 17: Switch test diagram
Checking Temperature Switches
The approximate switch point
should be known for testing
temperature switches. In the
Setup, below the switch point
to be expected, a removal
temperature will be set at
which the probe can be
removed without risk.
A lower and an upper limit temperature, UGT (lower limit temp.) and
OGT (upper limit temp.) are defined approx. 5 K above and below
the switch point.
At program start, the calibrator will control the temperature to the
removal temperature. After ENTER was pressed, the calibrator will
heat up to the lower limit temperature (UGT) with full heating
power. From there on, it will maximally heat to the upper limit
temperature (OGT) with the set gradient. If there is no switching
between the lower limit temperature (UGT) and the upper limit
temperature (OGT), the device will heat to the predefined removal
temperature.
If the device switches as expected between the lower (UGT) and
upper (OGT) limit temperatures, the switch temperature is displayed
as "t-up". The calibrator immediately starts to cool to record the
second switch point "t-down" in downward direction. Thereafter,
the removal temperature is controlled. The hysteresis is the
difference between the "t-up" and "t-down" temperatures.
Defective Temperature Switches
If the temperature switch does not switch within the selected range,
the calibrator will maximally heat to the upper limit temperature
(OGT) and then cool to removal temperature.