VEGA VEGASON 64 4 … 20 mA_HART four-wire - Manual (Page 23)

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 B 63-48 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.
V
oltage supply with mains voltage and current output are carried along
separate two-wire connection cables if reliable separation is required.
T
he voltage supply range can differ depending on the instrument
version.
T he data for power supply are specified in chapter "Technical data".
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.
F
or 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.
U se cable with round cross-section. A cable outer diameter of 5 … 9 mm
(0.2 … 0.35 in) ensures the seal effect of the cable gland. If you are
using cable with a different diameter or cross-section, exchange the
seal or use a suitable cable gland.
I f screened cable is necessary, 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 equalisation
(
low impedance).
Note safety instructions
Take note of
safety instruc-
tions for Ex ap-
plications
Select power supply
Selecting connection
cable
Cable screening and
grounding
VEGASON 64 • 4 … 20 mA/HART four-wire 23
5 C onnecting to power supply
28781
-
EN
-081127