7ML19985JB02 SITRANS Probe LU (PROFIBUS PA) – INSTRUCTION MANUAL Page 87
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H: Parameters
Entering breakpoints in PDM:
a. First go to Linearization > PV (volume/level) units, and select the
desired volume units.
b. The default for level values is percent: if you want to select units
instead, go to Input > Sensor Calibration > Unit (level), and select the
desired unit.
c. Go to > Linearization/Tank Shape, and select Linearization table
option.
d. Go to Detailed Setup > Volume.
e. In Level 1, enter a level value for breakpoint 1 (point 1 should always
be 0).
f. In Volume 1, enter the corresponding volume value for breakpoint 1
(point 1 should always be 0).
g. Repeat steps c and d until values have been entered for all the
required breakpoints.The highest level and volume values should
correspond to the maximum volume setting or 2.4.7 (High Level Pt)
Example:
Flow
The level and volume breakpoints can be also be used to calculate head level and
flow rate in an open channel device. (For more information please see Open
Channel Monitoring (OCM) on page 39.)
Use the level breakpoints to enter head level values, and the volume breakpoints
to enter flow volumes. Each segment defined by a head breakpoint requires a
corresponding flow value, so that SITRANS Probe LU can make the head-to-flow
calculations.
Use the Flow table associated with your open channel device (Parshall flume, v-notch
weir, or other measuring device) to calculate the flow rate for each breakpoint.
Note: Changing 2.4.7 (High Level Point) after programming the level/volume points will
change the level setting and proportionally increase or decrease the volume values at
the new level setting.
Note: Breakpoint values are for example purposes only.
4
20
9
5
0
Breakpoint
number
3
2
1
Breakpoint
Number
Level
value
(m)
Volume
value
(l)
10 0
25500
3 9 3000
4 20 8000
Level
value
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