Vaisala HMT360Series - Grounding Procedures

Electrical connections ________________________________________________________________
Vaisala _________________________________________________________________________ 28
FIGURE 4-5 MTL5044 (galvanic isolator).
Grounding
When grounding the transmitter, follow the local requirements. Use at least 4 mm
2
grounding cable when grounding the transmitter or barrier. Note that the allowed
resistance between barrier and system ground must be less than 1 ohm. See the figure
below.
FIGURE 4-6 Grounding.
HAZARDOUS AREA
-Ch2+-Ch1+
HMT360 Connection
board
5
4
1
2
9
12
11
SAFE AREA
Load Ch1
Load Ch2
20...35VDC
Vs+
Vs-
-
+
-
+
+
-
+
-
14
13
MTL5044
Zener
Barrier
Instrument
system
Barrier ground
S
y
stem
g
roun
d
-Ch1+
-Ch2+
HAZARDOUS AREA SAFE AREA