VEGA VEGAPULS SR 68 4 … 20 mA_HART - four-wire - Manual (Page 31)

31
5 Connecting to power supply
VEGAPULS SR 68 • 4 … 20 mA/HART - four-wire
38295-EN-130624
Considerable potential differences exist inside galvanic plants as well
as vessels with cathodic corrosion protection.
Warning:
Very large equalisation currents can flow through the cable screen
when the screen is grounded on both ends.
To avoid this in such applications, the cable screen must be connect-
ed to ground potential only at one end (in the switching cabinet). The
cable screen must not be connected to the internal ground terminal in
the sensor and the outer ground terminal on the housing must not be
connected to the potential equalisation!
Information:
The metallic parts of the instrument (process fitting, transmitter, con-
centric tube, etc.) are conductively connected with the inner and outer
ground terminal on the housing. This connection exists either directly
via connecting 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 Connection
The voltage supply and signal output are connected via the spring-
loaded terminals in the housing.
The connection to the display and adjustment module or to the inter-
face 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 cover
2. Loosen compression nuts of the cable glands
3. Remove approx. 10 cm (4 in) of the cable mantle (signal output),
strip approx. 1 cm (0.4 in) insulation from the ends of the indi-
vidual wires
4. Insert the cable into the sensor through the cable entry
Cable screening and
grounding with potential
differences
Connection technology
Connection procedure