Emerson Process Management ROSEMOUNT 5300 - Manual (Page 133)

Reference Manual
00809-0100-4530, Rev BA
July 2009
7-3
Rosemount 5300 Series
ANALYZING THE
MEASUREMENT SIGNAL Rosemount Radar Master (RRM) and other tools using enhanced EDDL has
powerful functions for advanced troubleshooting. Using the Echo Curve plot
function, an instant view of the tank signal is shown. Measurement problems
can be solved by studying the position and amplitude of the different pulses.
Figure 7-1. The Echo Curve
presents all visible echoes
In a typical measurement situation, the following pulses appear in the
diagram:
Reference. This pulse is caused by the transition between transmitter head
and probe. It is used by the transmitter as a reference at level measurements.
The pulse amplitude depends on the probe type and installation geometry.
Product surface. This pulse is caused by a reflection on the product surface.
Interface. This pulse is caused by reflection on the interface between an
upper product and a bottom product with a relatively high dielectric constant.
This pulse is shown when the transmitter is in Measurement Mode=Level &
Interface.
Probe End. It is caused by reflection on the probe end. If the probe is
grounded, the pulse will be positive.
Different amplitude thresholds are used to filter out unwanted signals and to
pick up the different pulses. The transmitter uses certain criteria to decide
which type of pulse that is detected.
For example, counting from the top of the tank, the first echo found above the
Surface Threshold is considered as the product surface. Other pulses further
away from the top, although above the Surface Threshold, are ignored.
When the surface echo is found, the next pulse below the product surface and
with a signal strength above the Interface Threshold, is considered as the
Interface.
The following amplitude thresholds are used for the Rosemount 5300 Series
transmitter:
Reference Threshold - amplitude threshold for detection of the Reference
pulse.
3.0 4.0 5.0 6.0
Interface Threshold
Surface Threshold
(ATC)
Probe End Threshold
Reference Threshold
Full Tank Threshold
Amp
litu
d
e, m
V
Distance, m
Reference
P1 Surface
P2 Interface
Probe End