VEGA VEGAFLEX 66 (-110…+400°C) Profibus PA - Manual (Page 18)

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 Profibus specifications
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.
Power is supplied via a Profibus DP/PA segment coupler or a
VEGALOG
571 EP input card. The power supply range can
differ depending on the instrument version.
Data for power supply are specified in chapter "Technical
data".
Connection is made with screened cable according to the
Profibus specification. Power supply and digital bus signal are
carried over the same two-wire connection cable.
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 other diameter or cross-
section, you have to exchange the seal or use a suitable cable
gland.
Please make sure that your installation is carried out according
to the Profibus specification. In particular, make sure that the
termination of the bus is done with appropriate terminating
resistors.
On the instrument with cable entry ½ NPT and plastic housing
there is a metallic ½" threaded insert moulded into the plastic
housing.
Note safety instructions
Take note of
safety instruc-
tions for Ex ap-
plications
Select power supply
Selecting connection
cable
Cable gland ½ NPT
18 VEGAFLEX 66 • Profibus PA
5 Connecting to power supply
32764
-EN
-080716