VEGA VEGABAR 61 4 … 20 mA_HART - Manual (Page 18)

Caution:
N
o grease should be used when screwing the NPT cable gland or
steel tube into the threaded insert. Standard grease can contain
additives that corrode the connection between threaded insert and
housing. This would influence the stability of the connection and the
tightness of the housing.
I f screened cable is necessary, connect the cable screen on both ends
to ground potential. In the sensor, the screen must be connected
directly to the internal ground terminal. The ground terminal on the
outside of the housing must be connected to the potential equalisation
(
low impedance).
I f potential equalisation currents are expected, the connection on the
processing side must be made via a ceramic capacitor (e. g. 1 nF,
1500 V). T
he low frequency potential equalisation currents are thus
suppressed, but the protective effect against high frequency interfer-
ence signals remains.
T ake note of the corresponding installation regulations for Ex
applications. In particular, make sure that no potential equalisation
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 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
Cable screening and
grounding
Select connec-
tion cable for Ex
applications
Single/Double chamber
housing
18 VEGABAR 61 • 4 … 20 mA/HART
5 C onnecting to power supply
27519
-EN
-081209