User manual for - FLOW METER SPP-N118
Example
6
: The user defined characteristic
Let the input mode = 4-20 mA, and the user selected the 10 segment characteristic. To do this
it is necessary to enter X and Y coordinates of 11 points (see
Menu ”FLouu”
).
The calculations will be done for three different input currents from example 2, so in
calculations some of the segments will be used only.
Let the following points will be given:
X1 =
“00.0.”
, Y1 =
“10.0”
,
X2=
“10.0.”
, Y2 =
“20.0”
,
....
X6 =
“30.0.”
, Y6 =
“30.0”
,
X7 =
“40.0.”
, Y7 =
“80.0”
,
....
X10 =
“90.0.”
, Y10 =
“900.0”
,
X11 =
“100.0.”
, Y11 =
“820.0”
,
Additionally all other points must to be defined and stored in the device memory.
a) I
in
=10 mA and I
n
= 0,375
The segment defined by X6 =
“30.0.”
i X7 =
“40.0.”
for this I
n
will be selected. Accordingly to
expressions given for user defined characteristic (see page 43) X6(PL) = 30,
Y6(PL) = 30,
X7(PH) = 40
,
Y7(PH) = 80 and I
p
= 0,3 , the displayed value :
W
=
I
n
−
I
p
×
[
Y
PH
−
Y
PL
]
[
X
PH
−
X
PL
]
×
100
Y
PL
=
=
0,375
−
0,3
×
[
80
−
30
]
[
40
−
30
]
×
100
30
≃
67
b) I
in
= 2,5 mA and I
n
= -0,0938, because of the normalized I
n
value is lower than 0, the
segment defined by X1 and X2 will be selected. X1(PL) = 0,
Y1(PL) = 10, X2(PH) = 10
,
Y2(PH) = 20 and I
p
= 0. For these values the displayed value W
≅
1.
c) I
in
= 20,5 mA and I
n
= 1,0313. , because of the normalized I
n
value is higher than 1, the
segment defined by X10 and X11 will be selected, and X10(PL) = 90,
Y10(PL) = 900,
X11(PH) = 100
,
Y11(PH) = 820 and I
p
= 0,9 for these values the displayed value W
≅
795.
Example
7
: Pipeline flow measurement
It is necessary to measure the pipeline flow using orifice plate (flange), which makes a
pressure difference 25 kPa, at flow rate 10 m
3
/h. Measurement can be done using differential
pressure sensor with range 25kPa, and current output signal 4-20mA. The sensor output
should be connected to
terminals, and proper configuration of input and
recalculation is required.
46
