User manual - CONTROLLER PUR-49D
Figure. 10.4 Example of user defined characteristic
10.2.
EXAMPLES OF CALCULATIONS
Example 1: Selection of the permissible input range (“4-20” mode)
If in “
4-20
” mode the user sets
“Lo r”
= 20,0% and
“Hi r”
= 10,0%, then permissible
input currents range will be equal: 3,2 mA ÷ 22 mA. Lower border of the range is the result of
calculations: 4 mA - 4 mA × 20%, and the higher : 20 mA + 20 mA × 10%.
Example 2: The normalized I
n
result calculation
Let the input mode = 4-20 mA. The normalized I
n
result is calculated accordingly to the
expression on page 55, so if I
in
= 10 mA then 10 mA - 4 mA = 6 mA, and this result should be
divided by the width of input range (16 mA). Finally the normalized result: I
n
= 6/16 = 0,375.
In case when input current exceeds nominal measurement range, calculations are similar. For
example if input current is equal 2,5 mA then I
n
= (2,5 - 4)/16
@
-0,0938, and if input current is
equal 20,5 mA then I
n
= (20,5 - 4)/16
@
1,0313.
Example 3: The linear characteristic
Let the input mode = 4-20 mA, and parameters
“Lo C”
and
“Hi C”
equal to -300 and 1200
respectively. The calculations will be done for three different input currents from example 2.
58
D
is
pl
ay
ed
v
al
ue
Prąd wejściowy [mA]
0
4
8
12
16
20
Y (PH)
0
0,2
0,35
0,5
0,7
1
0,9
Y (PL)
X = „20.0.”
X = „35.0.”
X (PL) = „50.0.”
X (PH) = „70.0.”
X = „90.0.”
X = „100.0.”
Input current [mA]
Normalized measurement I
n
(for 0-20 mA range)
5-elements characteristic
