5
C
onnecting to power supply
5
.
1
P
reparing the connection
A
lways keep in mind the following safety instructions
:
l
C
onnect only in the complete absence of line voltage
l
I
f voltage surges are expected
,
install overvoltage arresters
P
ower supply and current signal are carried on the same two
-
wire
cable
.
T
he voltage supply range can di
ff
er depending on the sensor
.
T
he data for power supply are speci
fi
ed in chapter
"
T
echnical data
"
.
P
rovide a reliable separation between the supply circuit and the mains
circuits according to
DIN VDE
0106
part
101
.
K
eep in mind the following additional factors that in
fl
uence the
operating voltage
:
l
O
utput voltage of the power supply unit can be lower under
nominal load
(
with a sensor current of
20
.
5
m
A
resp
.
22
m
A
in
case of fault message
)
l
I
n
fl
uence of additional instruments in the circuit
(
see load values in
chapter
"
T
echnical data
"
)
O
peration of
VEGADIS
62
in a
HART
multidrop system with the signal
conditioning instruments
VEGAMET
625
or
VEGASCAN
693
is not
supported
.
T
he instrument is connected with standard two
-
wire cable without
screen
.
I
f electromagnetic interference is expected which is above the
test values of
EN
61326
-
1
for industrial areas
,
screened cable should
be used
.
F
or instruments with housing and cable gland
,
use 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
,
exchange the seal or use a suitable cable gland
.
W
e generally recommend the use of screened cable for
HART
multidrop mode
.
W
ith plastic housing
,
the
NPT
cable gland or the
C
onduit steel tube
must be screwed without grease into the threaded insert
.
M
ax
.
torque for all housings see chapter
"
T
echnical data
"
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
).
S
afety instructions
V
oltage supply
C
onnection cable
C
able gland
½
NPT
C
able screening and
grounding
VEGADIS
62
13
5
C
onnecting to power supply
36469
-
EN
-
120329
