Connecting - Siemens SITRANS LG270 Operating Instructions Manual

Cable screening and
grounding
Connection technology
Connection procedure
PBD-51041507
Note:
Prior to setup you have to replace these protective caps with ap-
proved cable glands or close the openings with suitable blind plugs.
On plastic housings, the NPT cable gland or the Conduit steel tube
must be screwed into the threaded insert without grease.
Max. torque for all housings, see chapter "Technical data".
If screened cable is required, we recommend connecting the cable
screening on both ends to ground potential. In the sensor, the cable
screening must be connected directly to the internal ground terminal.
The ground terminal on the outside of the housing must be connected
to the ground potential (low impedance).
In Ex systems, the grounding is carried out according to the installa-
tion regulations.
In electroplating plants as well as plants for cathodic corrosion protec-
tion it must be taken into account that significant potential differences
exist. This can lead to unacceptably high currents in the cable screen
if it is grounded at both ends.
Note:
The metallic parts of the instrument (process fitting, sensor, concen-
tric tube, etc.) are connected with the internal and external ground
terminal on the housing. This connection exists either directly via
the conductive metallic parts or, in case of instruments with external
electronics, via the screen of the special connection cable.
You can find specifications on the potential connections inside the
instrument in chapter "Technical data".
5.2

Connecting

The voltage supply and signal output are connected via the spring-
loaded terminals in the housing.
Connection to the display and adjustment module or to the interface
adapter is carried out via contact pins in the housing.
Information:
The terminal block is pluggable and can be removed from the
electronics. To do this, lift the terminal block with a small screwdriver
and pull it out. When reinserting the terminal block, you should hear it
snap in.
Proceed as follows:
1. Unscrew the housing lid
2. If a display and adjustment module is installed, remove it by turn-
ing it slightly to the left
3. Loosen compression nut of the cable gland and remove blind
plug
4. Remove 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. Insert the cable into the sensor through the cable entry
SITRANS LG270 - Operating Instructions
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