VEGA VEGAFLEX 82 Profibus PA - Manual (Page 21)

21
5 Connecting to power supply
VEGAFLEX 82 • Profibus PA
44220-EN-130910
5 Connecting to power supply
5.1 Preparing the connection
Always keep in mind the following safety instructions:
•
Connect only in the complete absence of line voltage
•
If overvoltage surges are expected, overvoltage arresters should
be installed
The voltage supply is provided by a Profibus DP /PA segment coupler.
The voltage supply range can differ depending on the instrument
version. You can find the data for voltage supply 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 a different diameter or cross-section,
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.
You can find detailed information of the cable specification, installa-
tion and topology in the "Profibus PA - User and Installation Guide-
line" on www.profibus.com.
With plastic housing, the NPT cable gland or the Conduit steel tube
must be screwed without grease into the threaded insert.
Max. torque for all housings see chapter "Technical data".
Make sure that the cable screen and grounding are carried out ac-
cording to Fieldbus specification. We recommend to connect the
cable screen to ground potential on both ends.
With 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).
5.2 Connecting
The voltage supply and signal output are connected via the spring-
loaded terminals in the housing.
The connection to the display and adjustment module or to the inter-
face adapter is carried out via contact pins in the housing.
Safety instructions
Voltage supply
Connection cable
Cable gland ½ NPT
Cable screening and
grounding
Connection technology