CiDRA SONARtrac PW VF-100 - Manual (Page 153)

20834-01 Rev 04 Page 8-9
Figure 2 4-20mA Output Set to 0 – 30 fps
Note: For a 4-20mA flow setting of 0-100% of range (assuming a
meter range of 3 to 30 ft/sec), the system Low Flow Cut Off of 3.0 fps,
from the 4
–20 mA output will be 5.6mA. At flows less than 3.0 fps,
greater than 30.0 fps, or if the meter is not working, the display will
read as configured in the setup of the ‘Out of Range’ (i.e. ‘Hold’ (at
last value), <4mA, 4mA or >20mA) and the ‘Overrange Rail’
parameters.
8.3.1.4 Out of Range
The Out of Range menu selection permits the user to specify the 4-
20mA output behavior when the meter cannot measure a valid flow
rate or GVF / SOS value. The settings allow a less than 4mA output
(‘<4mA’ actual output of ~3mA), a greater than 20mA output (‘>20mA’
actual output of ~21mA), a constant 4mA output (‘4mA’), and a hold
last valid reading output (‘Hold’).
8.3.1.5 Overrange Rail
The Overrange Rail selection is used to select the output behavior
when the flow velocity (and corresponding flow rate) or GVF / SOS
goes below or above the ‘Low End’ or ‘High End’ settings made
earlier, but is still within the overall measurement range of the meter.
Default is ‘Enable’, where the 4-20mA output will go to either
minimum or full scale. If this option is ‘Disabled’, the meter will output
as previously set up in ‘Out of Range’ when the meter goes below or
above the range.
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5.6
4-20mA Output vs. Flow Velocity
Flow Velocity (fps)
mA
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