Differential Level Application
This type of application monitors the difference between two liquid levels, hence two
transducers are required. The HydroRanger I monitors the two levels, calculates the
difference and displays the differential as the reading. The following parameters should
be left at their factory setting:
•
volume conversion (P-34)
•
display conversion (P-37)
•
offset (P-62)
•
velocity compensation (P-63)
•
temperature compensation (P-65)
In the run mode, the reading display will show the absolute difference between the
levels, hence there are no negative readings. The level at transducer 1 or 2 may be
viewed individually by pressing "PT 1" or "PT 2" respectively.
When calibrating as a differential level detector:
•
P-2, mode: option 3 must be selected for DLD operation
•
P-3, empty distance to transducer: represents the lowest or common level
•
P-4, span: represents differential level corresponding to the 20 mA value
•
P-6, mA output: select range
•
P-20, function: option 14 must be selected for relay 5 to operate as scanner
•
P-32, mA output: may be dedicated to correspond to differential or level
under transducer # 1
On alarm and pump relay functions with setpoints referenced to zero, the setpoints are
common to both levels. The in bounds, out of bounds, rate of change and sequential
relay functions are not allowed.
In the event that the echo on either transducer is lost:
•
if set for fail-safe high: the differential reading will display the maximum
differential level (P-4)
•
if set for fail-safe low: the differential reading will display zero
•
if set for fail-safe hold: the display will hold its present reading after the
fail-safe timer has expired
In order to use the HydroRanger I as a differential level detector, TB-1 must be wired as
in Figure 3 and both transducers must be installed at the same level.
Refer to Figure 6 for application notes.
PL-399 6 – 25
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