Measurement Response; Damping - Siemens SITRANS LUT400 Operating Instructions Manual

Measurement Response

Note: Units are defined in Quick Start (1.1.) and are in meters by default.
Response Rate 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. Response Rate
automatically adjusts the three rate parameters that affect the output response rate.
When Response
Rate set to:
Slow
*
Medium
Fast

Damping

Damping Filter (2.2.3.) 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.
Damping example
time constant = 2 seconds
input (level) change = 2 m
Note: Damping Filter can be set to 0 in order to display measurement readings as fast
as fill/empty rates permit. Fill Rate per Minute, and Empty Rate per Minute work in
conjunction with Damping Filter, therefore, if readings are slow to respond to changes,
check that Fill and Empty Rates are set to values greater than or equal to the desired
Response Rate.
Page 262 SITRANS LUT400 (HART) – OPERATING INSTRUCTIONS
Fill Rate per Minute (2.3.1.)/
Empty Rate per Minute (2.3.2.)
automatically adjust to:
0.1 m/min
1.0 m/min
10.0 m/min
input (level)
Damping Filter
(2.3.3.) automatically
adjusts to:
100.0 s
10.0 s
0.0 s
Time (s)
smoothed output
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