VEGA VEGASON 66 Profibus PA - Manual (Page 25)

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).
In systems without potential equalisation, connect the cable
screen directly to ground potential at the power supply unit and
at the sensor. In the connection box or T-distributor, the screen
of the short stub to the sensor must not be connected to
ground potential or to another cable screen. The cable screens
to the power supply unit and to the next distributor must be
connected to each other and also connected to ground
potential via a ceramic capacitor (e.g. 1 nF, 1500 V). The low
frequency potential equalisation currents are thus suppressed,
but the protective effect against high frequency interference
signals remains.
The total capacitance of the cable and of all capacitors must
not exceed 10 nF in Ex applications.
Take note of the corresponding installation regulations for Ex
applications. In particular, make sure that no potential equal-
isation currents flow over the cable screen. In case of
grounding on both sides this can be achieved by the use of a
capacitor or a separate potential equalisation.
5.2 Connection steps
Proceed as follows:
1 Unscrew the housing cover
2 Loosen compression nut of the cable entry
3 Remove approx. 10 cm (4 in) of the cable mantle (current
output), strip approx. 1 cm (0.4 in) insulation from the ends
of the individual wires
4 Insert the cable into the sensor through the cable entry
5 Lift the opening levers of the terminals with a screwdriver
6 Insert the wire ends into the open terminals according to
the wiring plan
7 Press the opening lever of the terminals downward, you will
hear the terminal spring closing
8 Check the hold of the wires in the terminals by lightly
pulling on them
9 Connect the screen to the internal ground terminal and the
external ground terminal to potential equalisation
Select connection
cable for Ex applica-
tions
VEGASON 66 - Profibus PA 25
Connecting to voltage supply
28789
-EN
-060731