Vega VEGABAR 65, Руководство по эксплуатации

Страница: 17 / 76

I n 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 . T he screen in the sensor must be connected
directly to the internal ground terminal . T he ground terminal outside on
the housing must be connected to the potential equalisation ( low
impedance ).
I
n systems without potential equalisation
,
connect the cable screen
directly to ground potential at the power supply unit and at the sensor .
I n 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
. T he 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
n F ,
1500
V ). T he low
frequency potential equalisation currents are thus suppressed , but the
protective e ff ect against high frequency interference signals remains .
T he total capacitance of the cable and of all capacitors must not exceed
10
n F in E x applications .
T ake note of the corresponding installation regulations for E x
applications . I n particular , make sure that no potential equalisation
currents fl ow over the cable screen . I n case of grounding on both sides
this can be achieved by the use of a capacitor or a separate potential
equalisation
.
5
.
2
C
onnection procedure
P roceed as follows :
1
U nscrew the housing cover
2
I f an indicating and adjustment module is installed , remove it by
turning it slightly to the left .
3
L
oosen compression nut of the cable entry
4
R emove approx .
10
cm of the cable mantle , strip approx .
1
cm
insulation from the individual wires
5
I nsert the cable through the cable gland into the sensor
6
L ift the opening levers of the terminals with a screwdriver ( see
following illustration )
7
I
nsert the wire ends into the open terminals according to the wiring
plan
8
P ress down the opening levers of the terminals , you will hear the
terminal spring closing
9
C heck the hold of the wires in the terminals by lightly pulling on
them
10
C onnect the screen to the internal ground terminal , connect the
outer ground terminal with potential equalisation
C able screening and
grounding
S elect connec -
tion cable for E x
applications
S ingle / D ouble chamber
housing
VEGABAR
65
• P ro fi bus PA
17
5
C onnecting to power supply
28253
-
EN
-
081209