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3.4.13 Potential Equalization / Grounding
The ENT-DC must be connected to a potential equalization at a PA-clamp (X2.1 X2.3). If 19" flush-type versions
are used potential equalization is accomplished through a screw connection with the 19" rack. The 19" rack
must be connected with PA.
The intrinsically safe interface X3 may not be connected to potential equalization in the safe area which means
that the shield of the line from the hazardous area may not be applied in the safe area. Refer to regulation VDE
0165.
The data line to interface X1 must be shielded due to interference reasons. The shield must be applied on the
ENT-DC side on PA. (PA via connector housing / jack).
It is not necessary to shield the supply line (24V) to interface X2. An optional shield can be placed onto PA via
X2.1.
Safe Area
PC
power
supply
24V DC
TDOCT-4038_ENG / 2015-01
X3
.1
.2
.3
.4
X1
X2
.1
.3
Warning
Compensating currents are generated by potential
shifting which may cause electrical sparks.
For this reason the shield of the hazardous line must be
put in place in the hazardous area and not in the safe
area.
PC
RS232 connection
TxD
RxD
GND
polarity
inversion !
power supply
+24V
24V DC
GND
ENT-DC
Exi-line
.2
.4
Warning
ENT-DC
RxD
Polarity inversion of the supply
TxD
GND
voltage!
Normally GND is connected to the PC
housing. If a power supply is
grounded and polarity has been
+24V
inverted a short circuit will occur on
GND
the data interface of the ENT-DC
which can destroy PC and ENT-DC.
Hazardous Area
Exi Terminal
20
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