Figure 7-31: Identifying the Hold Off Distance/UNZ in the Echo Curve Plot
A. Amplitude, mV
B. Distance, m
C. Hold Off Distance/UNZ
D. Disturbance
E. Surface peak
F. Surface Threshold
2. Set the Hold Off Distance/UNZ to the desired value.
a) HART
®
: Select Configure → Manual Setup → Level Setup → Probe.
FOUNDATION
™
Fieldbus: Select Configure → Manual Setup → Probe.
b) Set Upper Null Zone to the desired value.
c) Select Send.
7.10.2
Disturbance echo handling
When the Basic Configuration is done, the transmitter may need a fine-tuning to handle
disturbing objects in the tank. The Amplitude Threshold Curve (ATC) function can be used
for disturbance echo handling with the Rosemount 5300 Level Transmitter.
Amplitude threshold curve
As shown in Figure 7-32, the ATC can be designed to filter out single disturbing echoes by
adapting the curve around the corresponding amplitude peak. It is important in this case
that the disturbance is fixed at a certain tank level. Disturbing echoes which may appear
different from time to time can be filtered out by raising the whole ATC.
Service and troubleshooting Reference Manual
April 2019 00809-0100-4530
230 Rosemount 5300 Level Transmitter
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