Vega VEGADIF 85 - Connecting to Power Supply and Bus System; Preparing the Connection

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5 Connecting to power supply and bus system
VEGADIF 85 • Modbus and Levelmaster protocol
53571-EN-230814
5 Connecting to power supply and bus
system
5.1 Preparing the connection
Always keep in mind the following safety instructions:
•
Carryoutelectricalconnectionbytrained,qualiedpersonnel
authorised by the plant operator
•
If overvoltage surges are expected, overvoltage arresters should
be installed
Warning:
Only connect or disconnect in de-energized state.
The operating voltage and the digital bus signal are routed via sepa-
rate two-wire connection cables.
Thedataforpowersupplyarespeciedinchapter"Technical data".
Note:
Power the instrument via an energy-limited circuit (power max. 100 W)
acc. to IEC 61010-1, e.g.
•
Class 2 power supply unit (acc. to UL1310)
•
SELV power supply unit (safety extra-low voltage) with suitable
internal or external limitation of the output current
The instrument is connected with standard two-wire, twisted cable
suitable for RS 485. If electromagnetic interference is expected which
is above the test values of EN 61326 for industrial areas, shielded
cable should be used.
Use cable with round cross section for instruments with housing and
cable gland. Use a cable gland suitable for the cable diameter to
ensurethesealeectofthecablegland(IPprotectionrating).
Make sure that the entire installation is carried out according to the
Fieldbusspecication.Inparticular,makesurethatthebusistermi-
nated with suitable terminating resistors.
Metric threads:
In the case of instrument housings with metric thread, the cable
glands are screwed in at the factory. They are sealed with plastic
plugs as transport protection.
Note:
You have to remove these plugs before electrical connection.
NPT thread:
In the case of instrument housings with self-sealing NPT threads, it is
not possible to have the cable entries screwed in at the factory. The
free openings for the cable glands are therefore covered with red dust
protection caps as transport protection.
Safety instructions
Voltage supply
Connection cable
Cable glands