Connecting To Power Supply; Preparing The Connection - Vega VEGABAR 53 Operating Instructions Manual

Note safety instructions
Take note of safety
instructions for Ex
applications
Select power supply
Selecting the connection ca-
ble
Cable entry 1/2" NPT
Cable screening and ground-
ing
VEGABAR 53 - Profibus PA

5 Connecting to power supply

5.1 Preparing the connection

Always observe the following safety instructions:
Connect only in the complete absence of line voltage
l
If overvoltages are expected, overvoltage arresters should
l
be installed acc. to Profibus specification.
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. The exact range is
stated in the "Technical data" in the "Supplement".
VEGABAR 53 is connected with screened cable acc. to the
Profibus specification. Power supply and digital bus signal are
carried over the same two-wire connection cable.
An outer cable diameter of 5 ... 9 mm ensures the seal effect
of the cable entry.
Please make sure that your installation is carried out acc. to
the Profibus specification. In particular, make sure that the
termination of the bus is done with appropriate terminating
resistors.
When using VEGABAR 53 with cable entry 1/2" NPT and
plastic housing, a metal 1/2" threaded insert is moulded into
the plastic housing.
Caution:
No grease should be used when screwing the NPT cable
gland or steel tube into the threaded insert. Standard grease
can contain additives affecting the connection between
threaded insert and housing. This will influence the stability of
the connection and the tightness of the housing.
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
Connecting to power supply
13