4 Transmitter
22
For dew point temperatures from -20 to -60°Ctd:
✓
Instrument in process.
1.
Connect the instrument to the electric power supply.
-
The instrument automatically passes through the initialization
phase and the display shows
Init. phase
.
2.
Wait for approx. 4 hours, until the instrument has completed the
pre-set 3 self-adjustment cycles.
-
After approx. 4 hrs: The reading
Init. phase
disappears from
the display, the instrument has reached optimal capacity.
For dew point temperatures from -60 to -90°Ctd:
✓
Instrument in process.
1.
Connect the instrument to the electric power supply.
-
The instrument automatically passes through the initialization
phase and the display shows
Init. phase
.
2.
Change the initialization phase to 4 cycles (via operating menu,
see Changing the adjustment phase page 34 or via P2A
software, see Self-adjustment page 59).
3.
Wait for approx. 5 hours, until the instrument has completed
4 self-adjustment cycles.
-
After approx. 5 hrs: The reading
Init. phase
disappears from
the display, the instrument has reached optimal capacity.
Pos: 41 /TD/Erste Schritte/MUF 63xx/1-Punkt-Abgleich 6781 @ 3\mod_1239794807174_79.doc @ 31163 @ 44 @ 1
4.3.2.2.
Self-adjustment
Conventional residual moisture sensors reveal extremely
increasing measurement uncertainties in case of low moisture
values, which are mainly caused by hysteresis effects. In case of
the residual moisture sensor of the testo 6781 these measurement
uncertainties are corrected by an automatic self-adjustment
procedure, which is automatically activated periodically over
definable cycle times. This means that extremely accurate
measuring results are also obtained down to -90 °C
td
.
For this purpose a thermally conductive temperature sensor is
attached to the back of the sensor element, which, besides the
temperature measurement, is also used as heater. A pair of
humidity and temperature values each is taken in both the
unheated and heated state. The probe deviation obtained from
these pairs of values is automatically corrected.