VEGA VEGAFLEX 66 (-200…+400°C) 4 … 20 mA_HART two-wire - Manual (Page 19)

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 (4 in) of the cable mantle, strip approx.
1 cm (0.4 in) of insulation from the ends of the individual wires
5 I nsert the cable into the sensor through the cable entry
6 L ift the opening levers of the terminals with a screwdriver (see
following illustration)
Cable screening and
grounding
VEGAFLEX 66 • 4 … 20 mA/HART two-wire 19
5 C onnecting to power supply
34173
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EN
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