U
se cable with round cross
-
section
.
A
cable outer diameter of
5
…
9
mm
(
0
.
2
…
0
.
35
in
)
ensures the seal e
ff
ect of the cable gland
.
I
f you are
using cable with a di
ff
erent diameter or cross
-
section
,
exchange the
seal or use a suitable cable gland
.
W
e generally recommend the use of screened cable for
HART
multidrop mode
.
O
n the instrument with cable entry
½
NPT
and plastic housing there is
a metallic
½"
threaded insert moulded into the plastic housing
.
C
aution
:
N
o grease should be used when screwing the
NPT
cable gland or
steel tube into the threaded insert
.
S
tandard grease can contain
additives that corrode the connection between threaded insert and
housing
.
T
his would in
fl
uence 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
.
I
n the sensor
,
the screen must be connected
directly to the internal ground terminal
.
T
he 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
n
F
,
1500
V
).
T
he low frequency potential equalisation currents are thus
suppressed
,
but the protective e
ff
ect against high frequency interfer
-
ence signals remains
.
T
ake note of the corresponding installation regulations for
E
x
applications
.
I
n particular
,
make sure that no potential equalisation
currents
fl
ow over the cable screen
.
I
n case of grounding on both sides
this can be achieved by the use of a capacitor or a separate potential
equalisation
.
5
.
2
C
onnection 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
)
insulation from the ends of the individual wires
5
I
nsert the cable through the cable gland into the sensor
6
L
ift the opening levers of the terminals with a screwdriver
(
see
following illustration
)
C
able gland
½
NPT
C
able screening and
grounding
VEGAFLEX
62
•
4
…
20
m
A
/
HART
two
-
wire
21
5
C
onnect to power supply
31837
-
EN
-
090831
