Samson 4785, Mounting And Operating Instructions

Page: 28 / 78

Note on selecting the cables and
wires:
If you are routing several intrinsi-
cally safe circuits in one multi-core
cable, you are required to observe
paragraph 12 of EN 60079-14 and
VDE 0165/8.98.
Note especially that for commonly
used insulation materials, such as
polyethylene, the radial thickness of
the conductor insulation must be at
least 0.2 mm. The diameter of a
single wire of a flexible conductor
must not be smaller than 0.1 mm.
The conductor ends must be pro-
tected against unlaying, e.g. by
using wire end ferrules. When two
separate cables are used for connec-
tion, an additional cable gland can
be installed.
Wire ends left unused must be
sealed with caps.
Positioners used in ambient tempera-
tures down to
−
40 °C must be fitted
with metal cable entries.
For terminal assignment, refer to Fig. 9 or
the designations on the cover plate inside
the positioner housing.
Bus line
The shielded PROFIBUS connecting cable
must be routed over the EMC-proof brass
cable gland (standard) of the positioner to
the terminals. The shield, which is placed
over the clamping insert, is connected over
a large area to the gland and housing.
1. To connect the bus line, loosen the coup-
ling nut and the clamping insert from
the positioner and remove the dust cap.
2. Slide the coupling nut and clamping in-
sert over the connecting cable.
3. Strip the shield off the bus line to the re-
quired connecting length and cut the
wire shield off up to a length of approx.
13 mm. If necessary, cut off any cable
core filling as well.
4. Disentangle the braided shield and pull
it over the clamping insert.
5. Press the clamping insert into the con-
necting screw gland and screw tight the
coupling nut until the connecting cable
is clamped tightly.
6. Route the two-wire bus line to the screw
terminals marked "EN 61158-2",
whereby no polarity has to be observed.
In exceptional cases, when the plant may
not allow such a connection, feed the cable
shield through the cable gland and connect
it to be capacitive over the terminal "S".
However, make sure that no conducting con-
nection occurs from the shield to the cable
gland or housing.
28
EB 8382-2 EN
Connections