Emerson Rosemount 5408, Справочное руководство

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Note
The Signal Quality may not be 10 even if the antenna is clean. The value depends on
antenna type, application conditions, configured surface threshold, as well as the
condition of the antenna.
Build up on the antenna and different surface conditions are factors that can result in a low
Signal Quality value. By setting an alert
(23)
, the Signal Quality value can be used to
schedule maintenance to clean the antenna, fine-tune the surface threshold, or detect and
monitor adverse surface conditions such as turbulence or foam.
Suitable alert limits vary from application to application. Appropriate value can be
determined by logging Signal Quality over time and viewing maximum/minimum values.
The Signal Quality Alert limit should be at least 1, but a better guideline is 2-3.
Figure C-18: Signal Quality Alert
%
'
$
(
&
)
*
A. Signal quality
B. Time
C. Alert ON
D. Deadband
E. Limit
F. The Signal Quality drops below the alert limit and an alert message is triggered.
G. The alert message is reset once the Signal Quality value rises above the Deadband range.
Limit
The Signal Quality value that will trigger the alert.
Deadband
The Deadband is a buffer zone so the alerts do not toggle on and off when the Signal
Quality fluctuates around the alert limit. The alert is set when value falls below the alert
limit. The alert is then cleared when value rises above the Deadband range.
C.4.3 High/low user defined alert
A high and low alert may be established to output an alert message when the
measurement readings exceed the specified limits.
Variable
Select the transmitter variable to use for the alert.
(23) Signal strength fluctuations are common when measuring solids, so Signal Quality alerts may not be appropriate in this
case.
Configuration parameters Reference Manual
February 2020 00809-0100-4408
272 Reference Manual