Vaisala HUMICAP HMT370EX Serie Bedienungsanleitung Seite 22

4.4 Wiring with Zener barriers
HAZARDOUS AREA
V
mA
Figure 6 Wiring diagram with Zener barriers
18
Test Points
V
mA
External
grounding
terminal
4 ... 20
mA
4 ... 20
mA
If the controller
uses voltage input,
use a shunt resistor:
SAFE AREA
Intrinsically
safe certified
Zener barriers
+ +
- -
+ +
- -
Controller
4 ... 20 mA
+
U = I*RI
RI
-
M212306EN-A
DC power supply
+
-
Controller
4 ... 20
mA
+
-
+
-