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 overvoltage surges are expected
,
overvoltage arresters
should be installed
T
ip
:
W
e recommend using
VEGA
overvoltage arresters
B
63
-
48
and Ü
SB
62
-
36
G
.
X
.
I
n hazardous areas you should take note of the appropriate
regulations
,
conformity and type approval certi
fi
cates of the
sensors and power supply units
.
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 instrument version
.
D
ata 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
.
T
he
VEGA
power supply units
VEGATRENN
149
A E
x
,
VEGAS
-
TAB
690
as well as all
VEGAMET
s meet this requirement
.
B
ear in mind the following factors regarding supply 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
or
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
"
)
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
for industrial areas
,
screened cable should be used
.
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 other diameter or cross
-
section
,
you have to exchange the seal or use a suitable cable
gland
.
N
ote safety instructions
T
ake note of
safety instruc
-
tions for
E
x ap
-
plications
S
elect power supply
S
electing connection
cable
VEGAFLEX
65
•
4
…
20
m
A
/
HART
15
5
C
onnecting to power supply
31845
-
EN
-
080716