Siemens SITRANS LR200 7ML5422, Руководство по эксплуатации

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SITRANS LR200 with mA/HART
Operating Instructions, 05/2019, A5E32337676-AE
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7.2.7.7 TVT setup (2.8.7.)
Auto false echo suppression (2.8.7.1.)
Auto false echo suppression is used together with Auto false echo suppression range
(2.8.7.2.) (Page 117) to screen out false echoes in a vessel with known obstructions. A
’learned TVT’ (time varying threshold) replaces the default TVT over a specified range. For a
more detailed explanation, refer to Auto False Echo Suppression (Page 176).
Notes
● Make sure material level is below all known obstructions at the moment Auto False Echo
Suppression is used to learn the echo profile. (An empty or almost empty vessel is
recommended.)
● Note the distance to material level when Auto False Echo learns the environment. Set
Auto False Echo Suppression Range to a shorter distance to avoid the material echo
being screened out.
● Set Auto False Echo Suppression and Auto False Echo Range during startup, if possible.
● If the vessel contains an agitator it should be running.
● Before adjusting these parameters, rotate the instrument for best signal (lower false-echo
amplitude).
Before Auto False Echo Suppression
①
TVT Hover Level
②
Default TVT
③
False echo
④
Material level
⑤
Echo marker
1. Determine Auto False Echo Suppression Range. Measure the actual distance from the
sensor reference point to the material surface using a rope or tape measure.
2. Subtract 0.5 m (20") from this distance, and use the resulting value.