VEGA VEGAFLEX 66 (-110…+400°C) 4 … 20 mA_HART - four-wire - Manual (Page 18)

5 Connecting to power supply
5.1 Preparing the connection
A
lways keep in mind the following safety instructions:
l
C
onnect only in the complete absence of line voltage
l
I f overvoltage surges are expected, overvoltage arresters
should be installed.
Tip:
W
e recommend using VEGA overvoltage arresters B63-48
and ÜSB 62-36G.X.
I n hazardous areas you should take note of the appropriate
regulations, conformity and type approval certificates of the
sensors and power supply units.
S upply voltage and current output are carried on separate two-
wire connection cables if reliable separation is required. The
supply voltage range can differ depending on the instrument
version.
D
ata for power supply is specified in chapter "Technical data".
T he standard version can be operated with an earth-
connected current output, the Exd version must be operated
with a floating output.
T his instrument is designed in protection class I. To maintain
this protection class, it is absolutely necessary that the ground
conductor be connected to the internal ground terminal. Take
note of the general installation regulations.
A
s a rule, connect the instrument to vessel ground (potential
euqalisation) or in case of plastic vessels to the next ground
potential. For this purpose there is a ground terminal on the
side of the instrument housing.
F
or power supply, an approved installation cable with PE
conductor is necessary.
T he 4 … 20 mA current output is connected with standard two-
wire cable without screen. If electromagnetic interference is
expected which is above the test values of EN 61326 for
industrial areas, screened cable should be used.
Note safety instructions
Take note of
safety instruc-
tions for Ex ap-
plications
Select power supply
Selecting connection
cable
18 VEGAFLEX 66 • 4 … 20 mA/HART - four-wire
5 C onnecting to power supply
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-EN
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