User manual for meter with U/I input SRP-77
10.1.3.
Square root characteristic
The normalized result is rooted and further conversion is done as for linear characteristic.
Conversion is made accordingly with the expression:
W
=
I
n
×
"Hi C"
−
"Lo C"
"Lo C" ,
where W means the displayed value.
Showed above expression is not valid when normalized result is negative. It is
possible for 4-20 mode only. In this case (I
n
<0) the displayed result is equal
“Lo C”
(see graphs below).
Figure. 10.3 Normal („Lo C” < ”Hi C) and inverted („Lo C” > ”Hi C) characteristic
10.1.4.
User defined characteristic
User defined characteristic is defined as set of X-Y points. Number of the points is variable and
may be set from 2 to 20 points which make linear segments (see graph and see
Menu ”inPt”
).
Due to the normalized result I
n
, the device computes specific segment, e.g. for characteristic
from figure below, and I
n
= 0,65 the segment between points X =
”50.0.”
and X =
”70.0.”
will
be chosen.
Let's mark those points as PL (point low) i PH (point high) - in this example PL=
“50.0,”
and
PH =
“70.0.”
, and the normalized result I
n
for the point PL as I
p
(in this example I
p
= I
n
(PL) =
0,5). The displayed result is calculated accordingly to the expression:
W
=
I
n
−
I
p
×
[
Y
PH
−
Y
PL
]
[
X
PH
−
X
PL
]
×
100
Y
PL
where Y(PH), X(PH), Y(PL), X(PL) mean values of X and Y coordinates of PH i PL points.
If the normalized result exceeds the user defined characteristic values, then specific
utmost segment, defined by two next points, is used for calculations. If characteristic
from figure below is used, and if I
n
>1 then segment defined by points
X(PL) =
“90.0.”
, X(PH) =
“100.0.”
will be used.
35
D
isp
la
ye
d
va
lu
e
Input current [mA]
0
4
8
12
16
20
Lo C
Hi C
D
isp
la
ye
d
va
lu
e
Input current [mA]
0
4
8
12
16
20
Hi C
Lo C
i
i
Содержание Simpact SRP-77
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