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OPERATING MANUAL HPC & UMC4
14.12.1 Sensor test on/off
The
Sensor test on/off
function allows the operator to activate or deactivate the monitoring function of the
excitation current.
Sensor test
[off]
According to the description in Section 13.4.3.1 Selection window/make a selection, the operator can
toggle between “on” and “off.” The standard factory setting is “off.”
14.12.2 Max. deviation of excitation
This function allows the operator to define a limiting value in the form of a percentage deviation from the
normal value. The excitation current is electronically limited to 50 mA (display value 500) and may take on
larger values for only a limited period of time (transient reactions).
Max. deviation
020 %
The current limiting value is displayed. As mentioned in Section 13.4.3.2 Input window/modify a value, the
value can be changed taking into account permissible fluctuations.
14.12.3 Self-test calibration
Since the quantity of the excitation current does not only depend on the sensor itself but also on the in-
stallation conditions and the viscosity and density of the fluid, the normal value can only be calculated on
site during operation using the
Self-test calibration
function.
Calibration
[no]
If the operator toggles to [yes] according to the description in Section 13.4.3.1 Selection window/make a
selection, the normal value will be calculated automatically. No additional information is needed for this
function.
14.12.4 Monitoring of sensor amplitude and excitation current
The first line of this window contains the amplitudes of the sensor signals S1 and S2 in 10 µV. Both val-
ues should be close to each other or identical (ideal case). The second line shows the excitation current
in 10 µA units.
S1 7749 S2 7812
E 1280
Example: The sensors have amplitudes of 77.49 mV and 78.12 mV. The excitation current is 12.8 mA.
These values are used as reference values for the self-test function. They are measured by using the
function 14.12.3 Self-test calibration on page 86. Afterwards they can be displayed or edited by this func-
tion.
