Tecfluid LU Series - Manual (Page 19)

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5.8 Dead zone distance
In some installations it can be useful to increase the dead zone value. For example, in
cases of standpipe measurements.
On this screen the dead zone distance in cm can be programed.
5.9 Dead zone and echo loss alarm
When the measured distance is into the dead zone, the instrument shows an alarm on the
current loop. This alarm can be programmed so that its value is either 3.6 mA or 22 mA.
When programming this value, the echo loss alarm value is programmed automatically
with the opposite value.
5.10 Hysteresis
When there is a sudden variation of the level then the filter should react as fast as possible to
give a correct reading of the new value.
On this screen the level variation in cm necessary to reset the filter can be programmed..
The filter controls for each reading the deviation of the instant level with respect to the
average level. If this deviation exceeds the 6% of the average value, the filter will stop
acting, indicating the instant value, and will start again the filtering process.
For example, consider an instrument measuring an average level of 2.4 m and the
programmed hysteresis is 4 cm..
The filter will continue to give average readings whilst the instant measured level is lower
than 2.36 m o higher than 2.44 m.