User's Manual

Page 144 SITRANS LR560 (FF)– INSTRUCTION MANUAL 7ML19985LY01
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D: Technical Reference
Measurement Response
Response Rate (2.3.6.1.) limits the maximum rate at which the display and output respond
to changes in the measurement. There are three preset options: slow, medium, and fast.
Once the real process fill/empty rate (m/min by default) is established, a response rate
can be selected that is slightly higher than the application rate. Changing Response Rate
resets Fill Rate/Min (2.3.6.2.), and Empty rate/Min (2.3.6.3.).
Damping
Filter Time Constant (2.5.7.1.) smooths out the response to a sudden change in level. This
is an exponential filter and the engineering unit is always in seconds.
In 5 time constants the output rises exponentially: from 63.2% of the change in the first
time constant, to almost 100% of the change by the end of the 5th time constant.
Loss of Echo (LOE)
A loss of echo (LOE) occurs when the calculated measurement is judged to be unreliable
because the echo confidence value has dropped below the echo confidence threshold.
Confidence (2.4.7.1.) describes the quality of an echo. Higher values represent higher
quality.
Echo Threshold (2.4.5.3.) defines the minimum confidence value required for an echo to
be accepted as valid and evaluated.
Note: Units are defined in Unit (2.3.1.) and are in meters by default.
Response Rate
(2.3.6.1.)
Fill Rate/Min (2.3.6.2.)/Empty rate/Min (2.3.6.3.)
Slow
0.1 m/min (0.32 ft/min)
* Medium
1.0 m/min (3.28 ft/min)
Fast
10.0 m/min (32.8 ft/min)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
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Series1 Series2
Level (m)
Time (s)
smoothed output
input (level)
Damping example
time constant = 2 seconds
input (level) change = 2 m