Connection Procedure - Vega VEGADIF 65 Operating Instructions Manual

Cable gland ½ NPT
Cable screening and
grounding
Single/Double chamber
housing
VEGADIF 65 • 4 ... 20 mA/HART
Use cable with round cross-section. A cable outer diameter of 5 ... 9 mm
(0.2 ... 0.35 in) ensures the seal effect of the cable gland. If you are
using cable with a different diameter or cross-section, exchange the
seal or use a suitable cable gland.
We generally recommend the use of screened cable for HART
multidrop mode.
On the instrument with cable entry ½ NPT and plastic housing there is
a metallic ½" threaded insert 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 that corrode the connection between threaded insert and
housing. This would influence the stability of the connection and the
tightness of the housing.
If 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).
If potential equalisation currents are expected, the connection on the
processing side must be made 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 interfer-
ence signals remains.
Take 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

Proceed as follows:
Unscrew the housing cover
1
If an indicating and adjustment module is installed, remove it by
2
turning it slightly to the left.
Loosen compression nut of the cable entry
3
Remove approx. 10 cm of the cable mantle, strip approx. 1 cm
4
insulation from the individual wires
Insert the cable through the cable gland into the sensor
5
Lift the opening levers of the terminals with a screwdriver (see
6
following illustration)
5 Connect to power supply
31