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Connecting to power supply
4
Preparing the connection
4.1
Note safety instructions
Always keep in mind the following safety instructions:
Connect only in the complete absence of line voltage
l
If overvoltage surges are expected, overvoltage arresters
l
should be installed
Tip:
We recommend VEGA overvoltage arresters B61-300
(external energy) and B62-36G (sensor supply).
Take note of safety instructions for Ex applications
In hazardous areas you should take note of the appro-
priate regulations, conformity and type approval certifi-
cates of the sensors and power supply units.
Select power supply
The voltage supply for the Ex separator VEGATRENN 149AEx
must be in the rangeof 20 ... 250 V AC, 50/60 Hz or 20 ... 250 V DC.
Selecting connection cable
For power supply of VEGATRENN 149AEx, an approved instal-
lation cable with PE conductor is necessary.
The sensor or the signal conditioning instrument are connected
with standard two-wire cable to the separator. If strong electro-
magnetic interference is expected, screened cable should be
used.
Cable screening and grounding
If screened cable is used, connect the cable screen on both ends
to ground potential. In the sensor, the screen must be connected
directly to the internal ground terminal. The ground terminal on the
outside of the housing must be connected to the potential equal-
isation.
If potential equalisation currents are expected, the screen con-
nection on the separator or signal processing instrument must be
made via a ceramic capacitor (e. g. 1 nF, 1500 V). The low fre-
quency potential equalisation currents are thus suppressed, but
the protective effect against high frequency interference signals
remains.
Select connection cable for Ex applications
Take note of the corresponding installation regulations
for Ex applications. In particular, make sure that no po-
tential equalisation currents flow over the cable screen.
In case of grounding on both sides this can be achieved
by the use of a capacitor or a separate potential equal-
isation.
Separating and protective instruments – Separating and protective instruments
Connecting to power supply
4.2
Wiring plan
Ex separator VEGATRENN 149AEx
Fig. 7: Terminal assignment VEGATRENN 149AEx
1
Sensor circuit
Processing circuit
2
3
Power supply
HART communication sockets
4
1
I+
I-
4
0+
0+H
0- L/+
2
3
N/-
7
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