VEGA VEGASON 64 Foundation Fieldbus - Manual (Page 23)

5 Connecting to power supply
5.1 Preparing the connection
Always keep in mind the following safety instructions:
l Connect only in the complete absence of line voltage
l If overvoltage surges are expected, overvoltage arresters should
be installed according to Foundation Fieldbus specification
Tip:
We recommend VEGA overvoltage arrester B63-32.
In hazardous areas you should take note of the appropriate
regulations, conformity and type approval certificates of the sensors
and power supply units.
Supply 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.
The data for power supply are specified in chapter "Technical data".
This 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.
As a rule, connect VEGASON 64 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.
For power supply, an approved installation cable with PE conductor is
necessary.
The signal output is connected with screened cable according to
Foundation Fieldbus specification.
Use 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.
In systems with potential equalisation, connect the cable screen
directly to ground potential at the power supply unit, in the connection
box and at the sensor. The screen in the sensor must be connected
directly to the internal ground terminal. The ground terminal outside on
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 • Foundation Fieldbus 23
5 Connecting to power supply
28793
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EN
-081127