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5 Connecting to power supply
VEGAPULS C 23 • Modbus and Levelmaster protocol
58349-EN-200806
5 Connecting to power supply
5.1 Preparing the connection
Always keep in mind the following safety instructions:
•
Carry out electrical connection by trained, qualified personnel
authorised by the plant operator
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 specified 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 device is supplied with a fixed cable. If an extension is required,
twisted two-wire cable suitable for RS 485 should be used for the
Modbus signal.
If electromagnetic interference is expected which is above the test
values of EN 61326-1 for industrial areas, shielded cable should be
used.
Make sure that the entire installation is carried out according to the
Fieldbus specification. In particular, make sure that the bus is termi
-
nated with suitable terminating resistors.
We recommend to connect the cable screening to ground potential at
one end on the supply side when using shielded cable.
5.2 Wiring plan
5
1
2
3
4
Fig. 18: Wire assignment in permanently connected connection cable
Wire colour
Function
Polarity
1
Brown
Voltage supply
Plus (+)
2
Blue
Voltage supply
Minus (-)
Safety instructions
Voltage supply
Connection cable
Cable screening and
grounding
Wire assignment, con-
nection cable