Vaisala HMP230 - Manual (Page 28)

HMP230 SERIES
User's Guide
M210225en-B
22
NOTE
When the cable is grounded as above, the metallic parts
of the sensor head, the shield of its cable, the transmit-
ter housing and the shield of the signal cable to external
system are all connected to each other. After this the
whole system can be grounded from one point only. If
the grounding is made via several points (sensor head,
transmitter housing, signal cable), make sure that the
different groundings are made to the same grounding
potential. Otherwise harmful grounding currents may be
generated. If you do the grounding via the transmitter
housing, use one serrated lock washer between a mount-
ing screw and the housing; the lock washer breaks the
paint on the housing.
When mains power supply is in use, the housing must be grounded by protec-
tive ground wire using a grounding screw at the right-hand side of the power
supply module (see Appendix 2).
3.4. Electrical connections
V
mA
+ -
C
H
1
+
C
H
1
-
C
H
2
+
C
H
2
-
2
4
V
+
X2
X1
V
mA
+ -
CH1- and CH2- are connected
together internally
CURRENT/VOLTAGE
OUTPUTS
POWER SUPPLY
(INTERNAL OR
EXTERNAL)
Do not use power supply
ground (-) as output signal
ground
OPENED COVER OF THE HMP230
Figure 20 Electrical connections