5
E
lectrical connection
5
.
1
P
reparing the connection
A
lways observe 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
VEGA
overvoltage arresters
B
61
-
300
(
power
supply
VEGASCAN
693
)
and
B
62
-
36
G
(
sensor supply
).
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
.
T
he power supply can be
20
…
253
V AC
,
50
/
60
H
z
.
P
ower supply of
VEGASCAN
693
is connected with standard
cable acc
.
to the national installation standards
.
S
tandard two
-
wire cable with screening can be used for
connecting the sensors
.
T
he screening is absolutely neces
-
sary to ensure interference
-
free operation with
HART
sensors
.
C
onnect 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 outside on the
sensor housing must be connected to the potential equal
-
isation
(
low impedance
).
I
f potential equalisation currents are expected
,
the screen
connection on the
VEGASCAN
693
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 interference signals
remains
.
T
ake note of the corresponding installation regulations for
E
x
applications
.
I
n particular
,
make sure that no potential equal
-
isation 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
.
N
ote safety instructions
T
ake note of safety
instructions for
E
x
applications
S
elect power supply
S
elect connection cable
C
able screening and ground
-
ing
S
elect connection
cable for
E
x applica
-
tions
12
VEGASCAN
693
-
15
-
channel
HART
signal conditioning instrument
E
lectrical connection
29252
-
EN
-
060513
