Surface Pulse Not Found - Emerson Rosemount 5400 Series Reference Manual

Reference Manual
00809-0100-4026, Rev HA
The surface thresholds should be set to approximately 20 % of the measured signal amplitude of
the product surface.
False echo area. False Echo Areas are set during the Measure and Learn function (see
setup" on page
Area can be adjusted manually.
Hold off distance - upper null zone. Measurements are not performed within the hold off
distance. By setting the hold off distance to zero, measurements can be performed close to the
flange. Consider near zone accuracy. See
Tank bottom. Measurements are not performed after the Tank Bottom limit.
7.3.2

Surface pulse not found

The amplitude thresholds are adjusted manually or during the Measure and Learn function to
appropriate values to filter out noise and other non-valid measurements from the measurement
signal.
The amplitude of the measurement signal, that is the amplitude of the signal reflected by the
product surface, is related to the actual dielectric constant of the product.
RRM has a plot function that allows viewing of the reflections in the tank.
If the amplitude threshold is too high, the product level will not be detected, as illustrated in
Figure
not filtered out.
Figure 7-2. Example 1: Surface Threshold is Too High
Reference
If there are disturbing objects in the tank, the threshold must be set carefully to avoid locking on
the wrong amplitude peak. In
product surface, that is a disturbance was interpreted as the product surface.
Service and Troubleshooting
92), when the disturbing object is larger than the surface echo. The False Echo
7-2. In a situation like this, the amplitude threshold is lowered so that the Surface peak is
Distance, m
Figure
Section 7: Service and Troubleshooting
"Near zone accuracy" on page
The surface threshold is above
the surface peak
7-3, the transmitter has locked on a peak above the actual
November 2014
"Guided
193.
Surface threshold =
ATC
133