User manual for regulated current source SZP-73
4.3.1.
Calculation of max. permissible load resistance
Figure 4.8 Circuit used for calculations
Calculation of resistance
R
0
has been made using above circuit, following signatures has
been assumed:
U
i
- minimal current output supply voltage assuring its proper operation
I
max.
- maximal current measured in current loop (20 mA)
U
s
- external power supply voltage (24V)
R
0
max.
=
U
s
−
U
i
I
max.
Values
U
i
= 6,5V
I
max.
= 20 mA and
U
s
= 24V gives:
R
0
max.
=
24
−
6,5
0,02
=
875
Current output of
SZP-73
can be powered from device power supply output.
To calculate max. resistance of the load, minimum available voltage (21.6V) should
be used as supply voltage. Then
R
0
max.
=
755
.
11
i
Power Supply
24 V DC
load (measurement)
resistance
+
-
8 9
+
-
U
i
R
0
