Endress+Hauser HART Proline Promass 83, Operating Instructions Manual

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Commissioning Proline Promass 83
78 Hauser
Triggering warning messages
If required, a limit value can be assigned to all the process/device parameters relevant to the
diagnostic functions. A warning message is triggered if this limit value is exceeded
→
function WARNING MODE (7403).
The limit value is entered into the measuring system as an absolute (+/-) or relative
deviation from the reference value
→
function WARNING LEVEL (74…).
Deviations arising and recorded by the measuring system can also be output via the current
or relay outputs.
Data interpretation
The way the data recorded by the measuring system is interpreted depends largely on the
application in question. This means that users must have a very good knowledge of their
specific process conditions and the related deviation tolerances in the process, which have to
be determined by the users themselves in each individual case.
For example, when using the limit function it is especially important to know the minimum
and maximum deviation tolerances allowed. Otherwise there is the danger that a warning
message is triggered inadvertently during "normal" process fluctuations.
There can be various reasons for deviating from the reference status. The following table
provides examples and pointers for each of the six diagnosis parameters recorded:
Diagnosis parameters Possible reasons for deviation
Mass flow A deviation from the reference status indicates possible zero point shift.
Density A deviation from the reference status can be caused by a change in the measuring
tube resonance frequency, e.g. from deposits in the measuring tube, corrosion or
abrasion.
Reference density The reference density values can be interpreted in the same way as the density
values. If the fluid temperature cannot be kept completely constant, you can analyze
the reference density (density at a constant temperature, e.g. at 20 °C) instead of the
density.
Ensure that the parameters required for calculating the reference density have been
correctly configured (functions REFERENCE TEMPERATURE and EXPANSION
COEFF.).
Temperature Use this diagnosis parameter to check the functionality of the PT 100 temperature
sensor.
Measuring tube damping A deviation from the reference status can be caused by a change in measuring tube
damping, e.g. from mechanical changes (coating buildup, corrosion, abrasion).
Sensor symmetry Use this diagnosis parameter to determine whether the sensor signals are
symmetrical.
Operating frequency
fluctuation A deviation in the operating frequency fluctuation indicates possible gas content in
the medium.
Tube damping fluctuation A deviation in the tube damping fluctuation indicates possible gas content in the
medium.